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DR ANTHONY MELVIN CRASTO, Born in Mumbai in 1964 and graduated from Mumbai University, Completed his Ph.D from ICT, 1991,Matunga, Mumbai, India, in Organic Chemistry, The thesis topic was Synthesis of Novel Pyrethroid Analogues, Currently he is working with GLENMARK LIFE SCIENCES LTD, Research Centre as Principal Scientist, Process Research (bulk actives) at Mahape, Navi Mumbai, India. Total Industry exp 30 plus yrs, Prior to joining Glenmark, he has worked with major multinationals like Hoechst Marion Roussel, now Sanofi, Searle India Ltd, now RPG lifesciences, etc. He has worked with notable scientists like Dr K Nagarajan, Dr Ralph Stapel, Prof S Seshadri, Dr T.V. Radhakrishnan and Dr B. K. Kulkarni, etc, He did custom synthesis for major multinationals in his career like BASF, Novartis, Sanofi, etc., He has worked in Discovery, Natural products, Bulk drugs, Generics, Intermediates, Fine chemicals, Neutraceuticals, GMP, Scaleups, etc, he is now helping millions, has 9 million plus hits on Google on all Organic chemistry websites. His friends call him Open superstar worlddrugtracker. His New Drug Approvals, Green Chemistry International, All about drugs, Eurekamoments, Organic spectroscopy international, etc in organic chemistry are some most read blogs He has hands on experience in initiation and developing novel routes for drug molecules and implementation them on commercial scale over a 30 PLUS year tenure till date June 2021, Around 35 plus products in his career. He has good knowledge of IPM, GMP, Regulatory aspects, he has several International patents published worldwide . He has good proficiency in Technology transfer, Spectroscopy, Stereochemistry, Synthesis, Polymorphism etc., He suffered a paralytic stroke/ Acute Transverse mylitis in Dec 2007 and is 90 %Paralysed, He is bound to a wheelchair, this seems to have injected feul in him to help chemists all around the world, he is more active than before and is pushing boundaries, He has 9 million plus hits on Google, 2.5 lakh plus connections on all networking sites, 90 Lakh plus views on dozen plus blogs, 233 countries, 7 continents, He makes himself available to all, contact him on +91 9323115463, email, Twitter, @amcrasto , He lives and will die for his family, 90% paralysis cannot kill his soul., Notably he has 33 lakh plus views on New Drug Approvals Blog in 233 countries...... , He appreciates the help he gets from one and all, Friends, Family, Glenmark, Readers, Wellwishers, Doctors, Drug authorities, His Contacts, Physiotherapist, etc

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Tasimelteon, タシメルテオン

ChemSpider 2D Image | Tasimelteon | C15H19NO2




609799-22-6 [RN]
Hetlioz [Trade name]
N-{[(1R,2R)-2-(2,3-Dihydro-1-benzofuran-4-yl)cyclopropyl]methyl}propanamide [ACD/IUPAC Name]
Propanamide, N-[[(1R,2R)-2-(2,3-dihydro-4-benzofuranyl)cyclopropyl]methyl]- [ACD/Index Name]

609799-22-6 cas, BMS-214778; VEC-162, ATC:N05CH03

  • Use:Treatment of sleep disorder; Melatonin receptor agonist
  • (1R,2R)-N-[2-(2,3-dihydrobenzofuran-4-yl)cyclopropylmethyl]propanamide
  • Formula:C15H19NO2, MW:245.3 g/mol
  • Hetlioz Vanda Pharmaceuticals, 2014

Approved fda 2014


Tasimelteon is a white to off-white crystalline powder, it is non hygroscopic, soluble in water across relevant pH values and freely soluble in alcohols, cyclohexane, and acetonitrile. Conducted in vivo studies demonstrate that tasimelteon is highly permeable substance. Photostability testing and testing on stress conditions demonstrated that the active substance degrades in light.

Tasimelteon exhibits stereoisomerism due to the presence of two chiral centres. Active substance is manufactured as a single, trans-1R,2R isomer. Enantiomeric purity is controlled routinely during manufacture of active substance intermediates by chiral HPLC/specific optical rotation and additionally controlled in the active substance. Stability data indicates tasimelteon is isomerically stable.

Polymorphism has been observed in polymorphic screening studies for tasimelteon and two forms have been identified. The thermodynamically more stable form has been chosen for development and the manufacturing process consistently yields active substance of single, desired polymorphic form. It was demonstrated that milling of the active substance does not affect polymorphic form. Polymorphism is additionally controlled in active substance release and shelf-life specifications using X-ray powder diffraction analysis.

Tasimelteon is synthesized in nine main steps using linear synthesis and using commercially available well-defined starting materials with acceptable specifications. Three intermediates are isolated for control of active substance quality including stereochemical control. The active substance is isolated by slow recrystallisation or precipitation of tasimelteon from an ethanol/water mixture which ensures the formation of desired polymorphic form. Up to two additional, optional recrystallisations may be performed for unmilled tasimelteon to ensure that milled tasimelteon active substance is of high purity. Seed crystals complying with active substance specifications can be used optionally. Active substance is jet milled (micronised) to reduce and control particle size, which is critical in finished product performance with regards to content uniformity and dissolution…….

launched in 2014 in the U.S. by Vanda Pharmaceuticals for the treatment of non-24-hour sleep-wake disorder in totally blind subjects. In 2015, the European Committee for Medicinal Products of the European Medicines Agency granted approval for the same indication.  In 2010 and 2011, orphan drug designations were assigned for the treatment of non-24 hour sleep/wake disorder in blind individuals without light perception in the U.S. and the E.U., respectively.

Tasimelteon (trade name Hetlioz) is a drug approved by the U.S. Food and Drug Administration (FDA)[2] in January 2014 for the treatment of non-24-hour sleep–wake disorder (also called Non-24, N24 and N24HSWD).[3] In June 2014, the European Medicines Agency accepted an EU filing application for tasimelteon[4] and in July 2015, the drug was approved in Europe for the treatment of non-24-hour sleep-wake rhythm disorder in totally blind adults,[5] but not in the rarer case of non-24 in sighted people.

Tasimelteon is a selective agonist for the melatonin receptors MT1 and MT2, similar to other members of the melatonin receptor agonistclass of which ramelteon (2005) and agomelatine (2009) were the first approved.[6] As a treatment for N24HSWD, as with melatonin or other melatonin derivatives, the patient may experience improved sleep timing while taking the drug. Reversion to baseline sleep performance occurs within a month of discontinuation.[7]



Tasimelteon (previously known as BMS-214,778) was developed for the treatment of insomnia and other sleep disorders. A phase II trial on circadian rhythm sleep disorders was concluded in March 2005.[8] A phase III insomnia trial was conducted in 2006.[9] A second phase III trial on insomnia, this time concerning primary insomnia, was completed in June 2008.[10] In 2010, the FDA granted orphan drug status to tasimelteon, then regarded as an investigational medication, for use in totally blind adults with N24HSWD.[11] (Through mechanisms such as easing the approval process and extending exclusivity periods, orphan drug status encourages development of drugs for rare conditions that otherwise might lack sufficient commercial incentive.)

On completion of Phase III trials, interpretations of the clinical trials by the research team concluded that the drug may have therapeutic potential for transient insomnia in circadian rhythm sleep disorders.[12] A year-long (2011–2012) study at Harvard tested the use of tasimelteon in blind subjects with non-24-hour sleep-wake disorder. The drug has not been tested in children nor in any non-blind people.

FDA approval

In May 2013 Vanda Pharmaceuticals submitted a New Drug Application to the Food and Drug Administration for tasimelteon for the treatment of non-24-hour sleep–wake disorder in totally blind people. It was approved by the FDA on January 31, 2014 under the brand name Hetlioz.[3] In the opinion of Public Citizen, an advocacy group, the FDA erroneously allowed it to be labelled without stating that it is only approved for use by totally blind people.[13] However, FDA updated its press release on Oct. 2, 2014 to clarify the approved use of Hetlioz, which includes both sighted and blind individuals. The update did not change the drug labeling (prescribing information).[14]


Experiments with rodents revealed fertility impairments, an increase in certain cancers, and serious adverse events during pregnancy at dosages in excess of what is considered the “human dose”.[15][16]

As expected, advisors to the US Food and Drug Administration have recommended approval of Vanda Pharmaceuticals’ tasimelteon, to be sold as Hetlioz, for the treatment of non-24-hour disorder in the totally blind.

The master body clock controls the timing of many aspects of physiology, behavior and metabolism that show daily rhythms, including the sleep-wake cycles, body temperature, alertness and performance, metabolic rhythms and certain hormones which exhibit circadian variation. Outputs from the

suprachiasmatic nucleus (SCN) control many endocrine rhythms including those of melatonin secretion by the pineal gland as well as the control of Cortisol secretion via effects on the hypothalamus, the pituitary and the adrenal glands. This master body clock, located in the SCN, spontaneously generates rhythms of approximately 24.5 hours. These non-24-hour rhythms are synchronized each day to the 24-hour day-night cycle by light, the primary environmental time cue which is detected by specialized cells in the retina and transmitted to the SCN via the retino-hypothalamic tract. Inability to detect this light signal, as occurs in most totally blind individuals, leads to the inability of the master body clock to be reset daily and maintain entrainment to a 24-hour day.

Non-24-Hour Disorder, Non-24, also referred to as Non-24-Hour Sleep-Wake Disorder, (N24HSWD) or Non-24-Hour Disorder, is an orphan indication affecting approximately 65,000 to 95,000 people in the U.S. and 140,000 in Europe. Non- 24 occurs when individuals, primarily blind with no light perception, are unable to synchronize their endogenous circadian pacemaker to the 24-hour light/dark cycle. Without light as a synchronizer, and because the period of the internal clock is typically a little longer than 24 hours, individuals with Non-24 experience their circadian drive to initiate sleep drifting later and later each day. Individuals with Non-24 have abnormal night sleep patterns, accompanied by difficulty staying awake during the day. Non-24 leads to significant impairment, with chronic effects impacting the social and occupational functioning of these individuals.

In addition to problems sleeping at the desired time, individuals with Non-24 experience excessive daytime sleepiness that often results in daytime napping.

The severity of nighttime sleep complaints and/or daytime sleepiness complaints varies depending on where in the cycle the individual’s body clock is with respect to their social, work, or sleep schedule. The “free running” of the clock results in approximately a 1-4 month repeating cycle, the circadian cycle, where the circadian drive to initiate sleep continually shifts a little each day (about 15 minutes on average) until the cycle repeats itself. Initially, when the circadian cycle becomes desynchronous with the 24h day-night cycle, individuals with Non-24 have difficulty initiating sleep. As time progresses, the internal circadian rhythms of these individuals becomes 180 degrees out of synchrony with the 24h day-night cycle, which gradually makes sleeping at night virtually impossible, and leads to extreme sleepiness during daytime hours.

Eventually, the individual’s sleep-wake cycle becomes aligned with the night, and “free-running” individuals are able to sleep well during a conventional or socially acceptable time. However, the alignment between the internal circadian rhythm and the 24-hour day-night cycle is only temporary.

In addition to cyclical nighttime sleep and daytime sleepiness problems, this condition can cause deleterious daily shifts in body temperature and hormone secretion, may cause metabolic disruption and is sometimes associated with depressive symptoms and mood disorders.

It is estimated that 50-75% of totally blind people in the United States (approximately 65,000 to 95,000) have Non-24. This condition can also affect sighted people. However, cases are rarely reported in this population, and the true rate of Non-24 in the general population is not known.

The ultimate treatment goal for individuals with Non-24 is to entrain or synchronize their circadian rhythms into an appropriate phase relationship with the 24-hour day so that they will have increased sleepiness during the night and increased wakefulness during the daytime. Tasimelteon

Tasimelteon is a circadian regulator which binds specifically to two high affinity melatonin receptors, Mella (MT1R) and Mellb (MT2R). These receptors are found in high density in the suprachiasmatic nucleus of the brain (SCN), which is responsible for synchronizing our sleep/wake cycle. Tasimelteon has been shown to improve sleep parameters in prior clinical studies, which simulated a desynchronization of the circadian clock. Tasimelteon has so far been studied in hundreds of individuals and has shown a good tolerability profile.

Tasimelteon has the chemical name: tr ns-N-[[2-(2,3-dihydrobenzofuran- 4-yl)cycloprop-lyl] methyl] propanamide, has the structure of Formula I:

Figure imgf000008_0001

Formula I

and is disclosed in US 5856529 and in US 20090105333, both of which are incorporated herein by reference as though fully set forth.

Tasimelteon is a white to off-white powder with a melting point of about 78°C (DSC) and is very soluble or freely soluble in 95% ethanol, methanol, acetonitrile, ethyl acetate, isopropanol, polyethylene glycols (PEG-300 and PEG- 400), and only slightly soluble in water. The native pH of a saturated solution of tasimelteon in water is 8.5 and its aqueous solubility is practically unaffected by pH. Tasimelteon has 2-4 times greater affinity for MT2R relative to MTIR. It’s affinity (¾) for MTIR is 0.3 to 0.4 and for MT2R, 0.1 to 0.2. Tasimelteon is useful in the practice of this invention because it is a melatonin agonist that has been demonstrated, among other activities, to entrain patients suffering from Non-24.

Metabolites of tasimelteon include, for example, those described in “Preclinical Pharmacokinetics and Metabolism of BMS-214778, a Novel

Melatonin Receptor Agonist” by Vachharajani et al., J. Pharmaceutical Sci., 92(4):760-772, which is hereby incorporated herein by reference. The active metabolites of tasimelteon can also be used in the method of this invention, as can pharmaceutically acceptable salts of tasimelteon or of its active metabolites. For example, in addition to metabolites of Formula II and III, above, metabolites of tasimelteon also include the monohydroxylated analogs M13 of Formula IV, M12 of Formula V, and M14 of Formula VI.

Formula IV

Figure imgf000010_0001

Formula V


Figure imgf000010_0002

Formula VI

Thus, it is apparent that this invention contemplates entrainment of patients suffering free running circadian rhythm to a 24 hour circadian rhythm by administration of a circadian rhythm regulator (i.e., circadian rhythm modifier) capable of phase advancing and/or entraining circadian rhythms, such as a melatonin agonist like tasimelteon or an active metabolite oftasimelteon or a pharmaceutically acceptable salt thereof. Other MT1R and MT2R agonists, i.e., melatonin agonists, can have similar effects on the master body clock. So, for example, this invention further contemplates the use of melatonin agonists such as but not limited to melatonin, N-[l-(2,3-dihydrobenzofuran-4- yl)pyrrolidin-3-yl]-N-ethylurea and structurally related compounds as disclosed in US 6,211,225, LY-156735 ((R)-N-(2-(6-chloro-5-methoxy-lH-indol- 3yl) propyl) acetamide) (disclosed in U.S. Patent No. 4,997,845), agomelatine (N- [2-(7-methoxy-l-naphthyl)ethyl]acetamide) (disclosed in U.S. Patent No.

5,225,442), ramelteon ((S)-N-[2-(l,6,7,8-tetrahydro-2H-indeno- [5,4-b] furan-8- yl)ethyl]propionamide), 2-phenylmelatonin, 8-M-PDOT, 2-iodomelatonin, and 6- chloromelatonin.

Additional melatonin agonists include, without limitation, those listed in U.S. Patent Application Publication No. 20050164987, which is incorporated herein by reference, specifically: TAK-375 (see Kato, K. et al. Int. J.

Neuropsychopharmacol. 2000, 3 (Suppl. 1): Abst P.03.130; see also abstracts P.03.125 and P.03.127), CGP 52608 (l-(3-allyl-4-oxothiazolidine-2-ylidene)-4- met- hylthiosemicarbazone) (See Missbach et al., J. Biol. Chem. 1996, 271, 13515-22), GR196429 (N-[2-[2,3,7,8-tetrahydro-lH-fur-o(2,3-g)indol-l- yl] ethyl] acetamide) (see Beresford et al., J. Pharmacol. Exp. Ther. 1998, 285, 1239-1245), S20242 (N-[2-(7-methoxy napth-l-yl) ethyl] propionamide) (see Depres-Brummer et al., Eur. J. Pharmacol. 1998, 347, 57-66), S-23478 (see Neuropharmacology July 2000), S24268 (see Naunyn Schmiedebergs Arch. June 2003), S25150 (see Naunyn Schmiedebergs Arch. June 2003), GW-290569, luzindole (2-benzyl-N-acetyltryptamine) (see U.S. Patent No. 5,093,352), GR135531 (5-methoxycarbonylamino-N-acetyltrypt- amine) (see U.S. Patent Application Publication No. 20010047016), Melatonin Research Compound A, Melatonin Agonist A (see IMSWorld R&D Focus August 2002), Melatonin

Analogue B (see Pharmaprojects August 1998), Melatonin Agonist C (see Chem. Pharm. Bull. (Tokyo) January 2002), Melatonin Agonist D (see J. Pineal Research November 2000), Melatonin Agonist E (see Chem. Pharm. Bull. (Tokyo) Febrary 2002), Melatonin Agonist F (see Reprod. Nutr. Dev. May 1999), Melatonin Agonist G (see J. Med. Chem. October 1993), Melatonin Agonist H (see Famaco March 2000), Melatonin Agonist I (see J. Med. Chem. March 2000), Melatonin Analog J (see Bioorg. Med. Chem. Lett. March 2003), Melatonin Analog K (see MedAd News September 2001), Melatonin Analog L, AH-001 (2-acetamido-8- methoxytetralin) (see U.S. Patent No. 5,151,446), GG-012 (4-methoxy-2- (methylene propylamide)indan) (see Drijfhout et al., Eur. J. Pharmacol. 1999, 382, 157-66), Enol-3-IPA, ML-23 (N-2,4-dinitrophenyl-5-methoxy-tryptamine ) (see U.S. Patent No. 4,880,826), SL-18.1616, IP-100-9 (US 5580878), Sleep Inducing Peptide A, AH-017 (see U.S. Patent No. 5,151,446), AH-002 (8-methoxy- 2-propionamido-tetralin) (see U.S. Patent No. 5,151,446), and IP-101.

Metabolites, prodrugs, stereoisomers, polymorphs, hydrates, solvates, and salts of the above compounds that are directly or indirectly active can, of course, also be used in the practice of this invention.

Melatonin agonists with a MT1R and MT2R binding profile similar to that of tasimelteon, which has 2 to 4 time greater specificity for MT2R, are preferred.

Tasimelteon can be synthesized by procedures known in the art. The preparation of a 4-vinyl-2,3-dihydrobenzofuran cyclopropyl intermediate can be carried out as described in US7754902, which is incorporated herein by reference as though fully set forth.

Pro-drugs, e.g., esters, and pharmaceutically acceptable salts can be prepared by exercise of routine skill in the art.

In patients suffering a Non-24, the melatonin and Cortisol circadian rhythms and the natural day/night cycle become desynchronized. For example, in patients suffering from a free-running circadian rhythm, melatonin and Cortisol acrophases occur more than 24 hours, e.g., >24.1 hours, prior to each previous day’s melatonin and Cortisol acrophase, respectively, resulting in desynchronization for days, weeks, or even months, depending upon the length of a patient’s circadian rhythm, before the melatonin, Cortisol, and day /night cycles are again temporarily synchronized.

Chronic misalignment of Cortisol has been associated with metabolic, cardiac, cognitive, neurologic, neoplastic, and hormonal disorders. Such disorders include, e.g., obesity, depression, neurological impairments.

Structure-activity relationship
Figure : Melatonin receptor agonists. The applied colors indicate the mutual properties with the general melatonin receptor agonists pharmacophore.


Tasimelteon has the chemical name: trans-N-[[2-(2,3-dihydrobenzofuran-4-yl)cycloprop-1yl]methyl]propanamide, has the structure of Formula I:

Figure US20130197076A1-20130801-C00001

and is disclosed in U.S. Pat. No. 5,856,529 and in US 20090105333, both of which are incorporated herein by reference as though fully set forth.

Tasimelteon is a white to off-white powder with a melting point of about 78° C. (DSC) and is very soluble or freely soluble in 95% ethanol, methanol, acetonitrile, ethyl acetate, isopropanol, polyethylene glycols (PEG-300 and PEG-400), and only slightly soluble in water. The native pH of a saturated solution of tasimelteon in water is 8.5 and its aqueous solubility is practically unaffected by pH. Tasimelteon has 2-4 times greater affinity for MT2R relative to MT1R. It’s affinity (Ki) for MT1R is 0.3 to 0.4 and for MT2R, 0.1 to 0.2. Tasimelteon is useful in the practice of this invention because it is a melatonin agonist that has been demonstrated, among other activities, to entrain patients suffering from Non-24.


(1R-trans)-N-[[2 – (2,3-dihydro-4 benzofuranyl) cyclopropyl] methyl] propanamide PATENT: BRISTOL-MYERS SQUIBB PRIORITY DATE: 1996 HYPNOTIC

Synthesis Tasimelteon



…………XXV (1S, 4R) -7,7-dimethyl-2-oxo-bicyclo [2.2.1] heptane-1-methanesulfonyl chloride


XXVI ammonium hydroxide


XXVII (1S, 4R) -7,7-dimethyl-2-oxo-bicyclo [2.2.1] heptane-1-methanesulfonamide


….XXVIII (3aS, 6R) -4,5,6,7-tetrahydro-8 ,8-dimethyl-3H-3a ,6-methano-2 ,1-benzisothiazole-2 ,2-dioxide

TREATED WITH LAH, ie double bond is reduced to get

…..XV (3aS, 6R, 7aR)-hexahydro-8 ,8-dimethyl-3H-3a ,6-methano-2 ,1-benzisothiazole-2 ,2-dioxide


I 3-hydroxybenzoic acid methyl ester

II 3-bromo-1-propene

III 3 – (2-propenyloxy) benzoic acid methyl ester

IV 3-hydroxy-2-(2-propenyl) benzoic acid methyl ester

V 2,3-dihydro-4-hydroxy-2-benzofurancarboxylic acid methyl ester

VI benzofuran-4-carboxylic acid methyl ester

VII benzofuran-4-carboxylic acid

VIII 2,3-dihydro-4-benzofurancarboxylic acid

IX 2,3-dihydro-4-benzofuranmethanol

X 2,3-dihydro-4-benzofurancarboxaldehyde

XI Propanedioic acid

XII (E) -3 – (2,3-dihydro-4-benzofuranyl) propenoic acid

XIII thionyl chloride

XIV (E) -3 – (2,3-dihydro-4-benzofuranyl) propenoyl chloride

XV (3aS, 6R, 7aR)-hexahydro-8 ,8-dimethyl-3H-3a ,6-methano-2 ,1-benzisothiazole-2 ,2-dioxide

XVI (3aS,6R,7aR)-1-[(E)-3-(2,3-dihydro-4-benzofuranyl)-1-oxo-2-propenyl]hexahydro-8,8-dimethyl-3H-3a,6-methano-2,1-benzisothiazole-2,2-dioxide

XVII (3aS,6R,7aR)-1-[[(1R,2R)-2-(2,3-dihydro-4-benzofuranyl)cyclopropyl]carbonyl]hexahydro-8,8-dimethyl-3H-3a,6-methano-2,1-benzisothiazole-2,2-dioxide

XVIII [R-(R *, R *)] -2 – (2,3-dihydro-4-benzofuranyl) cyclopropanemethanol

XIX [R-(R *, R *)] -2 – (2,3-dihydro-4-benzofuranyl) cyclopropanecarboxaldehyde

XX hydroxylamine hydrochloride

XXI [R-(R *, R *)] -2 – (2,3-dihydro-4-benzofuranyl) cyclopropanecarbaldehyde oxime

XXII [R-(R *, R *)] -2 – (2,3-dihydro-4-benzofuranyl) cyclopropanemethanamine

XXIII propanoyl chloride

XXIV D-camphorsulfonic acid

XXV (1S, 4R) -7,7-dimethyl-2-oxo-bicyclo [2.2.1] heptane-1-methanesulfonyl chloride

XXVI ammonium hydroxide

XXVII (1S, 4R) -7,7-dimethyl-2-oxo-bicyclo [2.2.1] heptane-1-methanesulfonamide

XXVIII (3aS, 6R) -4,5,6,7-tetrahydro-8 ,8-dimethyl-3H-3a ,6-methano-2 ,1-benzisothiazole-2 ,2-dioxide


– Patents: Benzofuran and dihydrobenzofuran melatonergic agents: US5856529 (1999)

Priority: US19960032689P, 10 Dec. 1996 (Bristol-Myers Squibb Company, U.S.)

– Preparation III (quinazolines): US2004044015 (2004) Priority: EP20000402845, 13 Oct. 2000

– Preparation of VII (aminoalkylindols): Structure-Activity Relationships of Novel Cannabinoid Mimetics Eissenstat et al, J.. Med. Chem. 1995, 38, 3094-3105

– Preparation XXVIII: Towson et al. Organic Syntheses, Coll. Vol. 8, p.104 (1993) Vol. 69, p.158 (1990)

– Preparation XV: Weismiller et al. Organic Syntheses, Coll. Vol. 8, p.110 (1993) Vol. 69, p.154 (1990).

– G. Birznieks et al. Melatonin agonist VEC-162 Improves sleep onset and maintenance in a model of transient insomnia. Sleep 2007, 30, 0773 Abstract.

-. Rajaratnam SM et al, The melatonin agonist VEC-162 Phase time immediately advances the human circadian system, Sleep 2006, 29, 0159 Abstract.

-. AK Singh et al, Evolution of a manufacturing route for a highly potent drug candidate, 229th ACS Natl Meet, March 13-17, 2005, San Diego, Abstract MEDI 576.

– Vachharajani NN et al, Preclinical pharmacokinetics and metabolism of BMS-214778, a novel melatonin receptor agonist, J Pharm Sci. 2003 Apr; 92 (4) :760-72.

. – JW Scott et al, Catalytic Asymmetric Synthesis of a melotonin antagonist; synthesis and process optimization. 223rd ACS Natl Meet, April 7-11, Orlando, 2002, Abstract ORGN 186.




Reaction Scheme 1

Figure imgf000020_0001

The syntheses of the 4-aryl-propenoic acid derivatives, 2 and 3, are shown in Reaction Scheme 1. The starting aldehydes, 1 , can be prepared by methods well known to those skilled in the art. Condensation of malonic acid with the aldehydes, 1, in solvents such as pyridine with catalysts such as piperidine or pyrrolidine, gives the 4-aryl- propenoic acid, 2. Subsequent conversion of the acid to the acid chloride using reagents such as thionyl chloride, phosphoryl chloride, or the like, followed by reaction with N,0-dimethyl hydroxylamine gives the amide intermediate 3 in good yields. Alternatively, aldehyde 1 can be converted directly to amide 3 using reagents such as diethyl (N-methoxy- N-methyl-carbamoylmethyl)phosphonate with a strong base such as sodium hydride.

Reaction Scheme 2

Figure imgf000020_0002

The conversion of the amide intermediate 3 to the racemic, trans- cyclopropane carboxaldehyde intermediate, 4, is shown in Reaction Scheme 2. Intermediate 3 was allowed to react with cyclopropanating reagents such as trimethylsulfoxonium iodide and sodium hydride in solvents such as DMF, THF, or the like. Subsequent reduction using reagents such as LAH in solvents such as THF, ethyl ether, or the like, gives the racemic, trans-cyclopropane carboxaldehyde intermediates, 4.

Reaction Scheme 3

Figure imgf000021_0001

Racemic cyclopropane intermediate 5 (R = halogen) can be prepared from intermediate 2 as shown in Reaction Scheme 3. Intermediate 2 was converted to the corresponding allylic alcohol by treatment with reducing agents such as sodium borohydride plus iodine in solvents such as THF. Subsequent acylation using reagents such as acetic anhydride in pyridine or acetyl chloride gave the allylic acetate which was allowed to react with cyclopropanating reagents such as sodium chloro-difluoroacetate in diglyme to provide the racemic, trans- cyclopropane acetate intermediates, 5. Reaction Scheme 4

Figure imgf000022_0001

The conversion of the acid 2 to the chiral cyclopropane carboxaldehyde intermediate, (-)-(trans)-4, is shown in Reaction Scheme 4. Intermediate 2 is condensed with (-)-2,10-camphorsultam under standard conditions, and then cyclopropanated in the presence of catalysts such as palladium acetate using diazomethane generated from reagents such as 1-methyl-3-nitro-1-nitrosoguanidine. Subsequent reduction using reagents such as LAH in solvents such as THF, followed by oxidation of the alcohol intermediates using reagents such as DMSO/oxalyl chloride, or PCC, gives the cyclopropane carboxaldehyde intermediate, (-)-(trans)-4, in good yields. The enantiomer, (+)-(trans)-4, can also be obtained employing a similar procedure using (+)-2,10- camphorsultam in place of (-)-2,10-camphorsultam.

When it is desired to prepare compounds of Formula I wherein m = 2, the alcohol intermediate may be activated in the conventional manner such as with mesyl chloride and treated with sodium cyanide followed by reduction of the nitrile group with a reducing agent such as LAH to produce the amine intermediate 6.

Reaction Scheme 5

Figure imgf000023_0001
Figure imgf000023_0002

Reaction Scheme 5 shows the conversion of intermediates 4 and 5 to the amine intermediate, 7, and the subsequent conversion of 6. or 7 to compounds of Formula I. The carboxaldehyde intermediate, 4, is condensed with hydroxylamine and then reduced with reagents such as LAH to give the amine intermediate, 7. The acetate intermediate 5 is hydrolyzed with potassium hydroxide to the alcohol, converted to the mesylate with methane sulfonyl chloride and triethyl amine in CH2CI2and then converted to the azide by treatment with sodium azide in solvents such as DMF. Subsequent reduction of the azide group with a reducing agent such as LAH produced the amine intermediate 7. Further reaction of 6 or 7 with acylating reagents gives compounds of Formula I. Suitable acylating agents include carboxylic acid halides, anhydrides, acyl imidazoles, alkyl isocyanates, alkyl isothiocyanates, and carboxylic acids in the presence of condensing agents, such as carbonyl imidazole, carbodiimides, and the like. Reaction Scheme 6

Figure imgf000024_0001

Reaction Scheme 6 shows the alkylation of secondary amides of Formula I (R2 = H) to give tertiary amides of Formula I (R2 = alkyl). The secondary amide is reacted with a base such as sodium hydride, potassium tert-butoxide, or the like, and then reacted with an alkylating reagent such as alkyl halides, alkyl sulfonate esters, or the like to produce tertiary amides of Formula I.

Reaction Scheme 7

Figure imgf000024_0002

Reaction Scheme 7 shows the halogenation of compounds of Formula I. The carboxamides, i (Q1 = Q2 = H), are reacted with excess amounts of halogenating agents such as iodine, N-bromosuccinimide, or the like to give the dihalo-compounds of Formula I (Q1 = Q2 = halogen). Alternatively, a stoichiometric amount of these halogenating agents can be used to give the monohalo-compounds of Formula I (Q1 = H, Q2 = halogen; or Q1 = halogen, Q2 = H). In both cases, additives such as lead IV tetraacetate can be used to facilitate the reaction. Biological Activity of the Compounds

The compounds of the invention are melatonergic agents. They have been found to bind human melatonergic receptors expressed in a stable cell line with good affinity. Further, the compounds are agonists as determined by their ability, like melatonin, to block the forskolin- stimulated accumulation of cAMP in certain cells. Due to these properties, the compounds and compositions of the invention should be useful as sedatives, chronobiotic agents, anxiolytics, antipsychotics, analgesics, and the like. Specifically, these agents should find use in the treatment of stress, sleep disorders, seasonal depression, appetite regulation, shifts in circadian cycles, melancholia, benign prostatic hyperplasia and related conditions



Preparation 1


Step 1 : N-Methoxy-N-methyl-benzofuran-4-carboxamide

A mixture of benzofuran-4-carboxylic acid [Eissenstat, et al.. J. Medicinal Chemistry, 38 (16) 3094-3105 (1995)] (2.8 g, 17.4 mmol) and thionyl chloride (25 mL) was heated to reflux for 2 h and then concentrated in vacuo. The solid residue was dissolved in ethyl acetate (50 mL) and a solution of N,O-dimethylhydroxylamine hydrochloride (2.8 g) in saturated NaHC03(60 mL) was added with stirring. After stirring for 1.5 h, the ethyl acetate layer was separated. The aqueous layer was extracted with ethyl acetate. The ethyl acetate extracts were combined, washed with saturated NaHCO3 and concentrated in vacuo to give an oil (3.2 g, 95.4%).

Step 2: Benzofuran-4-carboxaldehyde

A solution of N-methoxy-N-methyl-benzofuran-4-carboxamide (3.2 g, 16.6 mmol) in THF (100 mL) was cooled to -45°C and then LAH (0.7 g, 18.7 mmol) was added. The mixture was stirred for 15 min, allowed to warm to -5°C, and then recooled to -45°C. Saturated KHS04 (25 mL) was added with vigorous stirring, and the mixture was allowed to warm to room temperature. The precipitate was filtered and washed with acetone. The filtrate was concentrated in vacuo to give an oil (2.3 g, 94%). Preparation 2


Step 1 : 2,3-Dihydrobenzofuran-4-carboxylic acid

Benzofuran-4-carboxylic acid (10.0 g, 61 .7 mmol) was hydrogenated (60 psi) in acetic acid (100 mL) over 10% Pd/C (2 g) for 12 hr. The mixture was filtered and the filtrate was diluted with water (500 mL) to give 2,3- dihydrobenzofuran-4-carboxylic acid as a white powder (8.4 g, 83%). A sample was recrystallized from isopropanol to give fine white needles (mp: 185.5-187.5°C).

Step 2: (2,3-Dihydrobenzofuran-4-yl)methanol

A solution of 2,3-dihydrobenzofuran-4-carboxylic acid (10 g, 61 mmol) in THF (100 mL) was stirred as LAH (4.64 g, 122 mmol) was slowly added. The mixture was heated to reflux for 30 min. The mixture was cooled and quenched cautiously with ethyl acetate and then with 1 N HCI (150 mL). The mixture was then made acidic with 12 N HCI until all the inorganic precipitate dissolved. The organic layer was separated, and the inorganic layer was extracted twice with ethyl acetate. The organic layers were combined, washed twice with brine, and then concentrated in vacuo. This oil was Kϋgelrohr distilled to a clear oil that crystallized upon cooling (8.53 g, 87.6%).

Step 3: 2.3-Dihydrobenzofuran-4-carboxaldehyde

DMSO (8.10 mL, 1 14 mmol) was added at -78°C to a stirred solution of oxalyl chloride in CH2CI2 (40 mL of a 2M solution). A solution of (2,3- dihydrobenzofuran-4-yl)methanol (8.53 g, 56.9 mmol) in CH2CI2 (35 mL) was added dropwise, and the solution stirred at -78°C for 30 min. Triethyl amine (33 mL, 228 mmol) was added cautiously to quench the reaction. The resulting suspension was stirred at room temperature for 30 min and diluted with CH2CI2 (100 mL). The organic layer was washed three times with water, and twice with brine, and then concentrated in vacuo to an oil (8.42 g, 100%) that was used without purification.

Preparation 16

(±)-(trans)-2-(2,3-Dihyd robenzofuran-4-yl)cyclopropane- carboxaldehyde

Step 1 : (±Htrans)-N-Methoxy-N-methyl-2-(2.3-dihydrobenzofuran-4- yhcyclopropanecarboxamide

Trimethylsulfoxonium iodide (9.9 g, 45 mmol) was added in small portions to a suspension of sodium hydride (1 .8 g, 45 mmol) in DMF (120 mL). After the foaming had subsided (10 min), a solution of (trans)- N-methoxy-N-methyl-3-(2,3-dihydrobenzofuran-4-yl)propenamide (3.5 g, 15 mmol) in DMF (60 mL) was added dropwise, with the temperature maintained between 35-40°C. The mixture was stirred for 3 h at room temperature. Saturated NH4CI (50 mL) was added dropwise and the mixture was extracted three times with ethyl acetate. The organic extracts were combined, washed with H2O and brine, dried over K2CO3, and concentrated in vacuo to give a white wax (3.7 g, 100%).

Step 2: (±)-(trans)- 2-(2.3-Dihydrobenzofuran-4-yl)cyclopropane- carboxaldehyde

A solution of (±)-(trans)-N-methoxy-N-methyl-2-(2,3-dihydrobenzofuran- 4-yl)cyclopropanecarboxamide (3.7 g, 15 mmol) in THF (10 mL) was added dropwise to a rapidly stirred suspension of LAH (683 mg, 18 mmol) in THF (50 mL) at -45°C, maintaining the temperature below -40°C throughout. The cooling bath was removed, the reaction was allowed to warm to 5°C, and then the reaction was immediately recooled to -45°C. Potassium hydrogen sulfate (3.4 g, 25.5 mmol) in H20 (50 mL) was cautiously added dropwise, the temperature maintained below – 30°C throughout. The cooling bath was removed and the suspension was stirred at room temperature for 30 min. The mixture was filtered through Celite and the filter cake was washed with ether. The combined filtrates were then washed with cold 1 N HCI, 1 N NaOH, and brine. The filtrates were dried over MgSO4, and concentrated in vacuo to give a clear oil (2.6 g, 99%).

Preparation 18


Step 1 : (-Htrans)-N-[3-(2.3-Dihvdrobenzofuran-4-yl)-propenoyll-2.10- camphorsultam

To a solution of (-)-2,10-camphorsultam (8.15 g, 37.9 mmol) in 50 mL toluene at 0°C was added sodium hydride (1.67 g, 41.7 mmol). After stirring for 0.33 h at 0°C and 0.5 h at 20°C and recooling to 0°C, a solution of 3-(2,3-dihydrobenzofuran-4-yl)-2-propenoyl chloride
(37.9 mmol), prepared in situ from the corresponding acid and thionyl chloride (75 mL), in toluene (50 mL), was added dropwise. After stirring for 18 h at 20°C, the mixture was diluted with ethyl acetate and washed with water, 1 N HCI, and 1 N NaOH. The organic solution was dried and concentrated in vacuo to give 15.8 g of crude product. Recrystallization form ethanol-methanol (600 mL, 1 :1) gave the product (13.5 g, 92%, mp 199.5-200°C).

Step 2: (-)-N-[[(trans)-2-(2,3-Dihydrobenzofuran-4-yl)-cyclopropylj- carbonylj-2, 10-camphorsultam

1 -Methyl-3-nitro-1 -nitrosoguanidine (23.88g 163 mmol) was added in portions to a mixture of 10 N sodium hydroxide (60 mL) and ether (200 mL) at 0°C. The mixture was shaken vigorously for 0.25 h and the ether layer carefully decanted into a solution of (-)-N-[3-(2,3-dihydrobenzofuran-4-yl)-2-propenoyl]-2,10-camphorsultam (9.67 g, 25 mmol) and palladium acetate (35 mg) in methylene chloride (200 mL). After stirring for 18 h, acetic acid (5 mL) was added to the reaction and the mixture stirred for 0.5 h. The mixture was washed with 1 N HCI, 1 N NaOH and brine. The solution was dried, concentrated in vacuo and the residue crystallized twice from ethanol to give the product (6.67 g, 66.5%, mp 157-159°C).

Step 3: (-)-(trans)-2-(2,3-Dihydrobenzofuran-4-yl)cyclopropane- methanol

A solution of (-)-N-[(trans)-2-(2,3-dihydrobenzofuran-4-yl)cyclo-propanecarbonylj-2,10-camphorsultam (4.3 g, 10.7 mmol) in THF (50 mL) was added dropwise to a mixture of LAH (0.81 g, 21.4 mmol) in THF (50 mL) at -45°C. The mixture was stirred for 2 hr while it warmed to 10°C. The mixture was recooled to -40°C and hydrolyzed by the addition of saturated KHS0 (20 mL). The mixture was stirred at room temperature for 30 minutes and filtered. The precipitate was washed twice with acetone. The combined filtrate and acetone washes were concentrated in vacuo. The gummy residue was dissolved in ether, washed with 1 N NaOH and 1 N HCI, and then dried in vacuo to give the product (2.0 g, 98.4%).

Step 4: (-)-(trans)-2-(2.3-Dihydrobenzofuran-4-yl)cyclopropane- carboxaldehyde DMSO (1.6 g, 21 mmol) was added to oxalyl chloride in CH2CI2(7.4 mL of 2 M solution, 14.8 mmole) at -78°C. The (-)-(trans)-2-(2,3-dihydrobenzofuran-4-yl)-cyclopropylmethanol (2.0 g, 10.5 mmol) in CH2CI2(15 mL) was added. The mixture was stirred for 20 min and then triethylamine (4.24 g, 42 mmol) was added. The mixture was warmed to room temperature and stirred for 30 min. The mixture was diluted with CH2CI2 and washed with water, 1 N HCI, and then 1 N NaOH. The organic layer was dried and concentrated iι> vacuo to give the aldehyde product (1.98 g, 100%).

Preparation 24

(-)-(trans)-2-(2.3-Dihydrobenzofuran-4-yl)cyclopropane-methanamine A mixture of (-)-(trans)-2-(2,3-dihydrobenzofuran-4-yl)cyclopropane-carboxaldehyde (1.98 g, 10.5 mmol), hydroxylamine hydrochloride (2.29 g, 33 mmol), and 30% NaOH (3.5 mL, 35 mmol), in 5:1
ethanol/water (50 mL) was heated on a steam bath for 2 h. The solution was concentrated in vacuo. and the residue mixed with water. The mixture was extracted with CH2CI2. The organic extracts were dried and concentrated in vacuo to give a solid which NMR analysis showed to be a mixture of the cis and trans oximes. This material was dissolved in THF (20 mL) and added to solution of alane in THF [prepared from LAH (1.14 g, 30 mmol) and H2S04 (1.47 g, 15 mmol) at 0°Cj. The reaction was stirred for 18 h, and quenched successively with water (1.15 mL), 15% NaOH (1.15 mL), and then water (3.45 mL). The mixture was filtered and the filtrate was concentrated in vacuo. The residue was mixed with ether and washed with water and then 1 N HCI. The acid washes were made basic and extracted with CH2CI . The extracts were dried and concentrated in vacuo to give the amine product (1.4 g, 70.5%). The amine was converted to the fumarate salt in ethanol (mp: 197-198°C).
Anal. Calc’d for C12H15NO • C4H404: C, 62.94; H, 6.27; N, 4.59.
Found: C, 62.87; H, 6.31 ; N, 4.52.


Example 2


This compound was prepared similar to the above procedure using propionyl chloride and (-)-(trans)-2-(2,3-dihydrobenzofuran-4-yl)- cyclopropanemethanamine to give an oil that solidified upon standing to an off-white solid (61 %, mp: 71-72°C). IR (NaCI Film): 3298, 1645, 1548, 1459, 1235 cm“1.

Mo5 : -17.3°

Anal. Calc’d for C15H19N02: C, 73.44; H, 7.87; N, 5.71 . Found: C, 73.28; H, 7.68; N, 5.58


Synthesis Path


Tasimelteon (Hetlioz)Tasimelteon, which is marketed by Vanda Pharmaceuticals as Hetlioz and developed in partnership with Bristol-Myers Squibb,is a drug that was approved by the US FDA in January 2014 for the treatment of non-24-hour sleep–wake disorder (also called Non-24, N24 and N24HSWD).234 Tasimelteon is a melatonin MT1
and MT2 receptor agonist; because it exhibits a greater affinity to the MT2 receptor than MT1, is also known as Dual Melatonin
Receptor Agonist.234 Two randomized controlled trials (phases II
and III) demonstrated that tasimelteon improved sleep latency
and maintenance of sleep with a shift in circadian rhythms, and
therefore has the potential to treat patients with transient insomnia
associated with circadian rhythm sleep disorders.235 Preclinical
studies showed that the drug has similar phase-shifting properties
to melatonin, but with less vasoconstrictive effects.236 The most
likely scale preparation of the drug, much of which has been published
in the chemical literature, is described below in Scheme 44.
Activation of commercial bis-ethanol 250 with 2.5 equivalents
of the Vilsmeier salt 251 followed by treatment with base resulted
an intramolecular cyclization reaction with the proximal phenol
and concomitant elimination of the remaining imidate to deliver
the vinylated dihydrobenzofuran 252 in 76% yield.237 Interestingly,
this reaction could be performed on multi-kilogram scale, required
no chromatographic purification, and generated environmentallyfriendly
DMF and HCl as byproducts.237 Sharpless asymmetric
dihydroxylation of olefin 252 delivered diol 253 in 86% yield and
impressive enantioselectivity (>99% ee). This diol was then activated
with trimethylsilyl chloride and then treated with base to generate epoxide 254.238 Next, a modified Horner–Wadsworth–
Emmons reaction involving triethylphosphonoacetate (TEPA, 255)
was employed to convert epoxide 254 to cyclopropane 256.239
The reaction presumably proceeds through removal of the acidic
TEPA proton followed by nucleophilic attack at the terminal epoxide
carbon. The resulting alkoxide undergoes an intramolecular
phosphoryl transfer reaction resulting in an enolate, which then attacked the newly formed phosphonate ester in an SN2 fashion
resulting in the trans-cyclopropane ester, which was ultimately
saponified and re-acidified to furnish cyclopropane acid 256.239
Conversion of this acid to the corresponding primary amide preceded
carbonyl reduction with sodium borohydride. The resulting
amine was acylated with propionyl chloride to furnish tasimelteon
(XXXI) as the final product in 86% yield across the four-step


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extra info

Org. Synth.199069, 154
[3H-3a,6-Methano-2,1-benzisothiazole, 4,5,6,7-tetrahydro-8,8-dimethyl-2,2-dioxide, (3aS)-]
Submitted by Michael C. Weismiller, James C. Towson, and Franklin A. Davis1.
Checked by David I. Magee and Robert K. Boeckman, Jr..
1. Procedure
(−)-2,10-Camphorsultam. A dry, 2-L, three-necked, round-bottomed flask is equipped with a 1.5-in egg-shaped Teflon stirring bar, a 250-mL addition funnel, and a 300-mL Soxhlet extraction apparatus equipped with a mineral oil bubbler connected to an inert-gas source. The flask is charged with 600 mL of dry tetrahydrofuran (THF) (Note 1) and6.2 g (0.16 mol) of lithium aluminum hydride (Note 2). Into the 50-mL Soxhlet extraction thimble is placed 35.0 g (0.16 mol) of (−)-(camphorsulfonyl)imine (Note 3) and the reaction mixture is stirred and heated at reflux. After all of the(camphorsulfonyl)imine has been siphoned into the reaction flask (3–4 hr), the mixture is allowed to cool to room temperature. The unreacted lithium aluminum hydride is cautiously hydrolyzed by dropwise addition of 200 mL of 1 Nhydrochloric acid via the addition funnel (Note 4). After the hydrolysis is complete the contents of the flask are transferred to a 1-L separatory funnel, the lower, silver-colored aqueous layer is separated, and the upper layer placed in a 1-L Erlenmeyer flask. The aqueous phase is returned to the separatory funnel and washed with methylene chloride (3 × 100 mL). After the reaction flask is rinsed with methylene chloride (50 mL), the organic washings are combined with the THF phase and dried over anhydrous magnesium sulfate for 10–15 min. Filtration through a 300-mL sintered-glass funnel of coarse porosity into a 1-L round-bottomed flask followed by removal of the solvent on arotary evaporator gives 33.5 g (95%) of the crude (−)-2,10-camphorsultam. The crude sultam is placed in a 250-mL Erlenmeyer flask and crystallized from approximately 60 mL of absolute ethanol. The product is collected on a 150-mL sintered-glass funnel of coarse porosity and dried in a vacuum desiccator to give 31.1 g (88%) of the pure sultam. A second crop of crystals can be gained by evaporating approximately half the filtrate; the residue is crystallized as above to give 1.4 g (4%). The combined yield of white crystalline solid, mp 183–184°C, [α]D −30.7° (CHCl3, c 2.3) is92% (Note 5) and (Note 6).
2. Notes
1. Tetrahydrofuran (Aldrich Chemical Company, Inc.) was distilled from sodium benzophenone.
2. Lithium aluminum hydride was purchased from Aldrich Chemical Company, Inc.
3. (−)-(Camphorsulfonyl)imine, [(7S)-(−)-10,10-dimethyl-5-thia-4-azatricyclo[,7]dec-3-ene 5,5-dioxide] was prepared by the procedure of Towson, Weismiller, Lal, Sheppard, and Davis, Org. Synth., Coll. Vol. VIII1993, 104.
4. The addition must be very slow at first (1 drop/5 sec) until the vigorous reaction has subsided.
5. The NMR spectrum of (−)-2,10-camphorsultam is as follows: 1H NMR (CDCl3) δ: 0.94 (s, 3 H, CH3), 1.14 (s, 3 H, CH3), 1.33 (m, 1 H), 1.47 (m,, 1 H), 1.80–2.05 (5 H), 3.09 (d, 1 H, J = 14), 3.14 (d, 1 H, J = 14), 3.43 (m, 1 H), 4.05 (br s, 1 H, NH); 13C NMR (CDCl3) δ: 20.17 (q, CH3), 26.51 (t), 31.55 (t), 35.72 (t), 44.44 (d), 47.15 (s), 50.08 (t), 54.46 (s), 62.48 (d).
6. Checkers obtained material having the same mp (183–184°C) and [α]D − 31.8° (CHCl3c 2.3).
3. Discussion
(−)-2,10-Camphorsultam was first prepared by the catalytic hydrogenation of (−)-(camphorsulfonyl)imine overRaney nickel.2 Lithium aluminum hydride reduction was used by Oppolzer and co-workers in their synthesis of the sultam.3,4 However, because of the low solubility of the sultam in tetrahydrofuran, a large amount of solvent was required.4 In the procedure described here the amount of solvent is significantly reduced by using a Soxhlet extractor to convey the imine slowly into the reducing medium.5
Oppolzer’s chiral auxiliary,6 (−)-2,10-camphorsultam, is useful in the asymmetric Diels–Alder reaction,3,4 and for the preparation of enantiomerically pure β-substituted carboxylic acids7 and diols,8 in the stereoselective synthesis of Δ2-isoxazolines,9 and in the preparation of N-fluoro-(−)-2,10-camphorsultam, an enantioselective fluorinating reagent.10

References and Notes
  1. Department of Chemistry, Drexel University, Philadelphia, PA 19104.
  2. Shriner, R. L.; Shotton, J. A.; Sutherland, H. J. Am. Chem. Soc.193860, 2794.
  3. Oppolzer, W.; Chapuis, C.; Bernardinelli, G. Helv. Chim. Acta198467, 1397.
  4. Vandewalle, M.; Van der Eycken, J.; Oppolzer, W.; Vullioud, C. Tetrahedron198642, 4035.
  5. Davis, F. A.; Towson, J. C.; Weismiller, M. C.; Lal, G.; Carroll,, P. J. J. Am. Chem. Soc.1988110, 8477.
  6. Oppolzer, W. Tetrahedron198743, 1969.
  7. Oppolzer, W.; Mills, R. J.; Pachinger, W.; Stevenson, T. Helv. Chim. Acta198669, 1542; Oppolzer, W.; Schneider, P. Helv. Chim. Acta198669, 1817; Oppolzer, W.; Mills, R. J.; Réglier, M. Tetrahedron Lett.198627, 183; Oppolzer, W.; Poli. G.Tetrahedron Lett.198627, 4717; Oppolzer, W.; Poli, G.; Starkemann, C.; Bernardinelli, G. Tetrahedron Lett.198829, 3559.
  8. Oppolzer, W.; Barras, J-P. Helv. Chim. Acta198770, 1666.
  9. Curran, D. P.; Kim, B. H.; Daugherty, J.; Heffner, T. A. Tetrahedron Lett.198829, 3555.
  10. Differding, E.; Lang, R. W. Tetrahedron Lett.198829, 6087.

Org. Synth.199069, 158
[4H-4A,7-Methanooxazirino[3,2-i][2,1]benzisothiazole, tetrahydro-9,9-dimethyl-, 3,3-dioxide, [4aS-(4aα,7α,8aR*)]]
Submitted by James C. Towson, Michael C. Weismiller, G. Sankar Lal, Aurelia C. Sheppard, Anil Kumar, and Franklin A. Davis1.
Checked by David I. Magee and Robert K. Boeckman, Jr..
1. Procedure
A. (+)-(1S)-10-Camphorsulfonamide. Into a 2-L, two-necked, round-bottomed flask, equipped with a 250-mL dropping funnel, a magnetic stirring bar, and a reflux condenser fitted with an outlet connected to a disposable pipettedipped in 2 mL of chloroform in a test tube for monitoring gas evolution, were placed 116 g (0.5 mol) ofcamphorsulfonic acid (Note 1) and 750 mL of reagent-grade chloroform. The suspension of camphorsulfonic acid was heated to reflux and 71.4 g (43.77 mL, 0.6 mol, 1.2 equiv) of freshly distilled thionyl chloride was added dropwise over a 1-hr period. Heating was continued until gas evolution (sulfur dioxide and hydrogen chloride) had ceased (approximately 9–10 hr). The resultant solution of camphorsulfonyl chloride in chloroform was converted tocamphorsulfonamide without further purification.
In a 5-L, two-necked, round-bottomed flask fitted with a 250-mL dropping funnel and a mechanical stirrer was placed a solution of 1.6 L of reagent-grade ammonium hydroxide solution and the flask was cooled to 0°C in an ice bath. The solution of the crude camphorsulfonyl chloride, prepared in the preceding section, was added dropwise to the ammonium hydroxide solution at 0–10°C over a period of 1 hr. The reaction mixture was warmed to room temperature, stirred for 4 hr, the organic layer separated, and the aqueous layer was extracted with methylene chloride (3 × 250 mL). The combined organic layers were washed with brine (250 mL) and dried over anhydrousmagnesium sulfate. Removal of the solvent on the rotary evaporator gave 104.0 g (90%) of the crudecamphorsulfonamide (Note 2) and (Note 3).
B. (−)-(Camphorsulfonyl)imine. A 1-L, round-bottomed flask is equipped with a 2-in. egg-shaped magnetic stirring bar, a Dean–Stark water separator, and a double-walled condenser containing a mineral oil bubbler connected to an inert gas source. Into the flask are placed 5 g of Amberlyst 15 ion-exchange resin (Note 4) and 41.5 g of the crude(+)-(1S)-camphorsulfonamide in 500 mL of toluene. The reaction mixture is heated at reflux for 4 hr. After the reaction flask is cooled, but while it is still warm (40–50°C), 200 mL of methylene chloride is slowly added to dissolve any(camphorsulfonyl)imine that crystallizes. The solution is filtered through a 150-mL sintered glass funnel of coarse porosity an the reaction flask and filter funnel are washed with an additional 75 mL of methylene chloride.
Isolation of the (−)-(camphorsulfonyl)imine is accomplished by removal of the toluene on the rotary evaporator. The resulting solid is recrystallized from absolute ethanol (750 mL) to give white crystals, 34.5–36.4 g (90–95%), mp225–228°C; [α]D −32.7° (CHCl3, c 1.9) (Note 5).
C. (+)-(2R, 8aS)-10-Camphorylsulfonyloxaziridine. A 5-L, three-necked, round-bottomed Morton flask is equipped with an efficient mechanical stirrer, a 125-mm Teflon stirring blade, a Safe Lab stirring bearing (Note 6), and a 500-mL addition funnel. Into the flask are placed the toluene solution of (−)-(camphorsulfonyl)imine (39.9 g, 0.187 mol)prepared in Step B and a room-temperature solution of 543 g (3.93 mol, 7 equiv based on oxone) of anhydrouspotassium carbonate dissolved in 750 mL of water. The reaction mixture is stirred vigorously and a solution of 345 g (0.56 mol, 6 equiv of KHSO5) of oxone dissolved in 1250 mL of water is added dropwise in three portions over 45 min(Note 7) and (Note 8). Completion of the oxidation is determined by TLC (Note 9) and the reaction mixture is filtered through a 150-mL sintered-glass funnel of coarse porosity to remove solids. The filtrate is transferred to a 3-L separatory funnel, the toluene phase is separated and the aqueous phase is washed with methylene chloride (3 × 100 mL). The filtered solids and any solids remaining in the Morton flask are washed with an additional 200 mL of methylene chloride. The organic extracts are combined and washed with 100 mL of saturated sodium sulfite, dried over anhydrousmagnesium sulfate for 15–20 min, filtered, and concentrated on the rotary evaporator. The resulting white solid is crystallized from approximately 500 mL of hot 2-propanol to afford, after drying under vacuum in a desiccator, 35.9 g(84%) of white needles, mp 165–167°C, [α]D +44.6° (CHCl3, c 2.2) (Note 10) and (Note 11).
(−)-(2S,8aR)-10-(camphorylsulfonyl)oxaziridine is prepared in a similar manner starting from (−)-10-camphorsulfonic acid; mp 166–167°C, [α]D +43.6° (CHCl3, c 2.2).
2. Notes
1. (1S)-(+)-10-Camphorsulfonic acid was purchased from Aldrich Chemical Company, Inc.
2. The crude sulfonamide is contaminated with 5–10% of the (camphorsulfonyl)imine, the yield of which increases on standing.
3. The 1H NMR spectrum of (+)-(1S)-10-camphorsulfonamide is as follows: (CDCl3) δ: 0.93 (s, 3 H, CH3), 1.07 (s, 3 H, CH3), 1.40–2.50 (m, 7 H), 3.14 and 3.53 (AB quartet, 2 H, CH2-SO2J = 15.1), 5.54 (br s, 2 H, NH2).
4. Amberlyst 15 ion-exchange resin is a strongly acidic, macroreticular resin purchased from Aldrich Chemical Company, Inc.
5. The spectral properties of (−)-(camphorsulfonyl)imine are as follows: 1H NMR (CDCl3) δ: 1.03 (s, 3 H, CH3), 1.18 (s, 3 H, CH3), 1.45–2.18 (m, 6 H), 2.65 (m, 1 H), 3.10 and 3.28 (AB quartet, 2 H, CH2-SO2J = 14.0); 13C NMR (CDCl3) δ: 19.01 (q, CH3), 19.45 (q, CH3), 26.64 (t), 28.44 (t), 35.92 (t), 44.64 (d), 48.00 (s), 49.46 (t), 64.52 (s), 195.52 (s); IR (CHCl3) cm−1: 3030, 2967, 1366. Checkers obtained material having identical melting point and [α]D−32.3° (CHCl3, c 1.8).
6. The SafeLab Teflon bearing can be purchased from Aldrich Chemical Company, Inc. A glass stirring bearing lubricated with silicone grease is unsatisfactory because the dissolved salts solidify in the shaft, causing freezing.
7. Efficient stirring is important and indicated by a milky white appearance of the solution.
8. Occasionally batches of oxone purchased from Aldrich Chemical Company, Inc., have exhibited reduced reactivity in this oxidation. Oxone exposed to moisture prior to use also gives reduced reactivity in this oxidation. If this occurs, oxone is added until oxidation is complete as determined by TLC (Note 9). Potassium carbonate is added as needed to maintain the pH at approximately 9.0. Oxone stored in the refrigerator under an inert atmosphere has shown no loss in reactivity for up to 6 months.
9. Oxidation is generally complete after addition of the oxone solution. The oxidation is monitored by TLC as follows. Remove approximately 0.5 mL of the toluene solution from the nonstirring solution, spot a 250-μm TLC silica gel plate, elute with methylene chloride, and develop with 10% molybdophosphoric acid in ethanol and heating(camphorsulfonyl)imine Rf = 0.28 and (camphorylsulfonyl)oxaziridine Rf = 0.62. If (camphorsulfonyl)imine is detected, stirring is continued at room temperature until the reaction is complete (see (Note 8)). If the reaction mixture takes on a brownish color after addition of oxone and has not gone to completion after 30 min, the reaction mixture is filtered through a 150-mL sintered-glass funnel of coarse porosity, and the solids are washed with 50 mL of methylene chloride. The aqueous/organic extracts are returned to the 5-L Morton flask and stirred vigorously and 52 g (0.08 mol, 1 equiv KHSO5) of oxone is added over 5 min and stirring continued until oxidation is complete (approximately 10–15 min).
10. The submitters employed a toluene solution of crude imine prepared in Part B and obtained somewhat higher yields (90–95%). However, the checkers obtained yields in this range on one half the scale using isolatedsulfonylimine.
11. The spectral properties of (+)-(camphorsulfonyl)oxaziridine are as follows: 1H NMR (CDCl3) δ: 1.03 (s, 3 H, CH3), 1.18 (s, 3 H, CH3), 1.45–2.18 (m, 6 H), 2.65 (d, 1 H), 3.10 and 3.28 (AB quartet, 2 H, CH2-SO2J = 14.0); 13C NMR (CDCl3) δ: 19.45 (q, CH3), 20.42 (q, CH3), 26.55 (t), 28.39 (t), 33.64 (t), 45.78 (d), 48.16 (s), 48.32 (t), 54.07 (s), 98.76 (s). The checkers obtained material (mp 165–167°C) having [α]D +44.7° (CHCl3, c 2.2).
3. Discussion
Camphorsulfonamide, required for the preparation of the (camphorsulfonyl)imine, was previously prepared in two steps. The first step involved conversion of camphorsulfonic acid to the sulfonyl chloride with PCl5 or SOCl2. The isolated sulfonyl chloride was converted in a second step to the sulfonamide by reaction with ammonium hydroxide. This modified procedure is more efficient because it transforms camphorsulfonic acid directly to camphorsulfonamide, avoiding isolation of the camphorsulfonyl chloride.
(Camphorsulfonyl)imine has been reported as a by-product of reactions involving the camphorsulfonamide.2,3,4,5Reychler in 1898 isolated two isomeric camphorsulfonamides,2 one of which was shown to be the(camphorsulfonyl)imine by Armstrong and Lowry in 1902.3 Vandewalle, Van der Eycken, Oppolzer, and Vullioud described the preparation of (camphorsulfonyl)imine in 74% overall yield from 0.42 mol of the camphorsulfonyl chloride.6 The advantage of the procedure described here is that, by using ammonium hydroxide, the camphorsulfonyl chloride is converted to the sulfonamide in >95% yield.7 The sulfonamide is of sufficient purity that it can be used directly in the cyclization step, which, under acidic conditions, is quantitative in less than 4 hr. These modifications result in production of the (camphorsulfonyl)imine in 86% overall yield from the sulfonyl chloride.
In addition to the synthesis of enantiomerically pure (camphorylsulfonyl)oxaziridine7 and its derivatives,8 the(camphorsulfonyl)imine has been used in the preparation of (−)-2,10-camphorsultam (Oppolzers’ auxiliary),6,9 (+)-(3-oxocamphorysulfonyl) oxaziridine,10 and the N-fluoro-2,10-camphorsultam, an enantioselective fluorinating reagent.11
The N-sulfonyloxaziridines are an important class of selective, aprotic oxidizing reagents.121314 Enantiomerically pure N-sulfonyloxaziridines have been used in the asymmetric oxidation of sulfides to sulfoxides (30–91% ee),15selenides to selenoxides (8–9% ee).16 disulfides to thiosulfinates (2–13% ee),5 and in the asymmetric epoxidation of alkenes (19–65% ee).17,18 Oxidation of optically active sulfonimines (R*SO2N=CHAr) affords mixtures of N-sulfonyloxaziridine diastereoisomers requiring separation by crystallization and/or chromatography.3
(+)-(Camphorylsulfonyl)oxaziridine described here is prepared in four steps from inexpensive (1S)-(+)- or (1R)-(+)-10-camphorsulfonic acid in 77% overall yield.7 Separation of the oxaziridine diastereoisomers is not required because oxidation is sterically blocked from the exo face of the C-N double bond in the (camphorsulfonyl)imine. In general, (camphorsulfonyl)oxaziridine exhibits reduced reactivity compared to other N-sulfonyloxaziridines. For example, while sulfides are asymmetrically oxidized to sulfoxides (3–77% ee), this oxaziridine does not react with amines or alkenes.7 However, this oxaziridine is the reagent of choice for the hydroxylation of lithium and Grignard reagents to give alcohols and phenols because yields are good to excellent and side reactions are minimized.19 This reagent has also been used for the stereoselective oxidation of vinyllithiums to enolates.20
The most important synthetic application of the (camphorylsulfonyl)oxaziridines is the asymmetric oxidation of enolates to optically active α-hydroxy carbonyl compounds.14,21,22,23,24 Chiral, nonracemic α-hydroxy carbonylcompounds have been used extensively in asymmetric synthesis, for example, as chiral synthons, chiral auxiliaries, and chiral ligands. This structural array is also featured in many biologically active natural products. This oxidizing reagent gives uniformly high chemical yields regardless of the counterion, and stereoselectivities are good to excellent (50–95% ee).9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24 Since the configuration of the oxaziridine three-membered ring controls the stereochemistry, both α-hydroxy carbonyl optical isomers are readily available. Representative examples of the asymmetric oxidation of prochiral enolates by (+)-(2R,8aS)-camphorylsulfonyl)oxaziridine are given in Tables I and II.

This preparation is referenced from:

  • Org. Syn. Coll. Vol. 8, 110
  • Org. Syn. Coll. Vol. 9, 212
  • References and Notes
    1. Department of Chemistry, Drexel University, Philadelphia, PA 19104.
    2. Reychler, M. A. Bull. Soc. Chim. III188919, 120.
    3. Armstrong, H. E.; Lowry, T. M. J. Chem. Soc., Trans.190281, 1441.
    4. Dauphin, G.; Kergomard, A.; Scarset, A. Bull. Soc. Chim. Fr.1976, 862.
    5. Davis, F. A.; Jenkins, Jr., R. H.; Awad, S. B.; Stringer, O. D.; Watson, W. H.; Galloy, J. J. Am. Chem. Soc.1982104, 5412.
    6. Vandewalle, M.; Van der Eycken, J.; Oppolzer, W.; Vullioud, C. Tetrahedron198642, 4035.
    7. Davis, F. A.; Towson, J. C.; Weismiller, M. C.; Lal, S.; Carroll, P. J. J. Am. Chem. Soc.1988110, 8477.
    8. Davis, F. A.; Weismiller, M. C.; Lal, G. S.; Chen, B. C.; Przeslawski, R. M. Tetrahedron Lett.198930, 1613.
    9. Oppolzer, W. Tetrahedron198743, 1969.
    10. Glahsl, G.; Herrmann, R. J. Chem. Soc., Perkin Trans. I1988, 1753.
    11. Differding, E.; Lang, R. W. Tetrahedron Lett.198829, 6087.
    12. For recent reviews on the chemistry of N-sulfonyloxaziridines, see: (a) Davis, F. A.; Jenkins, Jr., R. H. in “Asymmetric Synthesis,” Morrison, J. D., Ed.; Academic Press: Orlando, FL, 1984, Vol. 4, Chapter 4;
    13. Davis, F. A.; Haque, S. M. in “Advances in Oxygenated Processes,” Baumstark, A. L., Ed.; JAI Press: London, Vol. 2;
    14. Davis, F. A.; Sheppard, A. C. Tetrahedron198945, 5703.
    15. Davis, F. A.; McCauley, Jr., J. P.; Chattopadhyay, S.; Harakal, M. E.; Towson, J. C.; Watson, W. H.; Tavanaiepour, I. J. Am. Chem. Soc.1987109, 3370.
    16. Davis, F. A.; Stringer, O. D.; McCauley, Jr., J. M. Tetrahedron198541, 4747.
    17. Davis, F. A.; Chattopadhyay, S. Tetrahedron Lett.198627, 5079.
    18. Davis, F. A.; Harakal, M. E.; Awad, S. B. J. Am. Chem. Soc.1983105, 3123.
    19. Davis, F. A.; Wei, J.; Sheppard, A. C.; Gubernick S. Tetrahedron Lett.198728, 5115.
    20. Davis, F. A.; Lal, G. S.; Wei, J. Tetrahedron Lett.198829, 4269.
    21. Davis, F. A.; Haque, M. S.; Ulatowski, T. G.; Towson, J. C. J. Org. Chem.198651, 2402.
    22. Davis, F. A.; Haque, M. S. J. Org. Chem.198651, 4083; Davis, F. A.; Haque, M. S.; Przeslawski, R. M. J. Org. Chem.198954, 2021.
    23. Davis, F. A.; Ulatowski, T. G.; Haque, M. S. J. Org. Chem.198752, 5288.
    24. Davis, F. A.; Sheppard, A. C., Lal, G. S. Tetrahedron Lett.198930, 779.
    25. Davis, F. A.; Sheppard, A. C.; Chen, B. C.; Haque, M. S. J. Am. Chem. Soc.1990112, 6679.

a US 5 856 529 (Bristol-Myers Squibb; 5.1.1999; appl. 9.12.1997; USA-prior. 10.12.1996).

    • b US 7 754 902 (Vanda Pharms.; 13.7.2010; appl. 18.5.2006).
  • treatment of circadian rhythm disorders:

    • US 8 785 492 (Vanda Pharms.; 22.7.2014; appl. 25.1.2013; USA-prior. 26.1.2012).
  • synthesis cis-isomer:

    • US 6 214 869 (Bristol-Myers Squibb; 10.4.2001; appl. 25.5.1999; USA-prior. 5.6.1998).


  1. USUS5856529 A
  2. USUS8785492 B2
  3. US5856529
  4. US8785492
  5. US9060995
  6. US9549913
  7. US9539234
  8. US9730910
  9. USRE46604
  10. US9855241


  1. Jump up^ “Tasimelteon Advisory Committee Meeting Briefing Materials”(PDF). Vanda Pharmaceuticals Inc. November 2013.
  2. Jump up^ “FDA transcript approval minutes” (PDF). FDA. November 14, 2013.
  3. Jump up to:a b Food and Drug Administration (January 31, 2014). “FDA approves Hetlioz: first treatment for non-24 hour sleep-wake disorder”. FDA.
  4. Jump up^ “tasimelteon (Hetlioz) UKMi New Drugs Online Database”. Retrieved August 6, 2014.
  5. Jump up^ “HETLIOZ® Receives European Commission Approval for the Treatment of Non-24-Hour Sleep-Wake Disorder in the Totally Blind”MarketWatch. PR Newswire. 7 July 2015. Retrieved 8 July 2015.
  6. Jump up^ Vachharajani, Nimish N.; Yeleswaram, Krishnaswamy; Boulton, David W. (April 2003). “Preclinical pharmacokinetics and metabolism of BMS-214778, a novel melatonin receptor agonist”. Journal of Pharmaceutical Sciences92 (4): 760–72. doi:10.1002/jps.10348PMID 12661062.
  7. Jump up^ Sack, R. L.; Brandes, R. W.; Kendall, A. R.; Lewy, A. J. (2000). “Entrainment of Free-Running Circadian Rhythms by Melatonin in Blind People”. New England Journal of Medicine343 (15): 1070–7. doi:10.1056/NEJM200010123431503PMID 11027741.
  8. Jump up^ “Safety and Efficacy of VEC-162 on Circadian Rhythm in Healthy Adult Volunteers”. |accessdate=May 15, 2014
  9. Jump up^ “VEC-162 Study in Healthy Adult Volunteers in a Model of Insomnia”. Retrieved May 15, 2014.
  10. Jump up^ “VEC-162 Study in Adult Patients With Primary Insomnia”. Retrieved May 15, 2014.
  11. Jump up^ Lynne Lamberg. “Improving Sleep and Alertness in the Blind (Part 5)”Matilda Ziegler Magazine for the Blind. Retrieved May 15, 2014.
  12. Jump up^ Shantha MW Rajaratnam; Mihael H Polymeropoulos; Dennis M Fisher; Thomas Roth; Christin Scott; Gunther Birznieks; Elizabeth B Klerman (2009-02-07). “Melatonin agonist tasimelteon (VEC-162) for transient insomnia after sleep-time shift: two randomised controlled multicentre trials”The Lancet373 (9662): 482–491. doi:10.1016/S0140-6736(08)61812-7PMID 19054552. Retrieved 2010-02-23.
  13. Jump up^ Carome, Michael (1 July 2015). “Outrage of the Month: FDA Makes Major Blunder After Approving Drug for Rare Sleep Disorder”Huffington Post. Retrieved 8 July 2015.
  14. Jump up^ Food and Drug Administration (January 31, 2014). “FDA NEWS RELEASE: FDA approves Hetlioz: first treatment for non-24 hour sleep–wake disorder in blind individuals”. FDA.
  15. Jump up^ “Side Effects Drug Center: Hetlioz Clinical Pharmacology”. RxList. February 10, 2014.
  16. Jump up^ “Side Effects Drug Center: Hetlioz Warnings and Precautions”. RxList. February 10, 2014. In animal studies, administration of tasimelteon during pregnancy resulted in developmental toxicity (embryofetal mortality, neurobehavioral impairment, and decreased growth and development in offspring) at doses greater than those used clinically.
Tasimelteon 2.svg
Tasimelteon ball-and-stick model.png
Clinical data
Trade names Hetlioz
License data
  • US:C (Risk not ruled out)
Routes of
ATC code
Legal status
Legal status
Pharmacokinetic data
Bioavailability not determined in humans[1]
Protein binding 89–90%
Metabolism extensive hepatic, primarily CYP1A2 and CYP3A4-mediated
Elimination half-life 0.9–1.7 h / 0.8–5.9 h (terminal)
Excretion 80% in urine, 4% in feces
CAS Number
ECHA InfoCard 100.114.889Edit this at Wikidata
Chemical and physical data
Formula C15H19NO2
Molar mass 245.32 g/mol
3D model (JSmol)



MOBILE-+91 9323115463


//////////////BMS-214778, VEC-162, Tasimelteon, Hetlioz, FDA 2014, 609799-22-6 , BMS-214778, VEC-162, ATC N05CH03, タシメルテオン , EU 2015, VANDA, BMS, orphan drug designations

Chemical and physical properties 

Tasimelteon has two stereogenic centers. Besides the medically used trans-1 R , 2 R isomer (in the picture above left), there are thus three further stereoisomers that do not arise in the synthesis.

Tasimelteon stereoisomerism.svg

Tasimelteon is a white to off-white crystalline non-hygroscopic substance, soluble in water at physiologically relevant pH levels and readily soluble in alcohols, cyclohexane and acetonitrile. The compound occurs in two crystal forms. It is an anhydrate melting at 74 ° C and a hemihydrate . [4] The hemihydrate is from about 35 ° C the water of hydration and converts thereby in the anhydrate form to. [4] The anhydrate crystallizes in a monoclinic lattice with the space group P 2 1 , and the hemihydrate crystallizes in a tetragonal lattice with the space group P 4 3 21 2. [4]

4  Kaihang Liu, Zhou Xinbo, Zhejing Xu, Bai Hongzhen, Jianrong Zhu Jianming Gu, Guping Tang, Liu Xingang, Hu Xiurong: anhydrate and hemihydrate of Tasimelteon: Synthesis, structure, and pharmacokinetic study in J. Pharm. Biomed. Anal. 151 (2018) 235-243, doi : 10.1016 / j.jpba.2017.12.035 .

Tradipitant, традипитант , تراديبيتانت , 曲地匹坦 ,



VLY-686,  LY686017

تراديبيتانت [Arabic]
曲地匹坦 [Chinese]
  • Molecular Formula C28H16ClF6N5O
  • Average mass 587.903 Da
622370-35-8  CAS
Methanone, [2-[1-[[3,5-bis(trifluoromethyl)phenyl]methyl]-5-(4-pyridinyl)-1H-1,2,3-triazol-4-yl]-3-pyridinyl](2-chlorophenyl)-

PHASE 2, Gastroparesis; Pruritus

pyridine-containing NK-1 receptor antagonist ie tradipitant, useful for treating anxiety, pruritus and alcoholism.

Vanda Pharmaceuticals, under license from Eli Lilly, was developing tradipitant, a NK1 antagonist, for treating anxiety disorder, pruritus and alcohol dependence. The company was also investigating the drug for treating gastroparesis. In February 2017, tradipitant was reported to be in phase 2 clinical development for treating anxiety and pruritus.

  • Originator Eli Lilly
  • Developer Eli Lilly; National Institute on Alcohol Abuse and Alcoholism; Vanda Pharmaceuticals
  • Class Antipruritics; Anxiolytics; Chlorobenzenes; Pyridines; Small molecules; Triazoles
  • Mechanism of Action Neurokinin 1 receptor antagonists; Substance P inhibitors

Highest Development Phases

  • Phase II Gastroparesis; Pruritus
  • Discontinued Alcoholism; Social phobia
  • The drug had been in phase II clinical trials at Lilly and the National Institute on Alcohol Abuse and Alcoholism for the treatment of alcoholism; however, no recent development has been reported for this research.
  • A phase II clinical trial for the treatment of social phobia has been completed by Lilly.

PATENT WO 2003091226

Albert Kudzovi Amegadzie, Kevin Matthew Gardinier, Erik James Hembre, Jian Eric Hong, Louis Nickolaus Jungheim, Brian Stephen Muehl, David Michael Remick, Michael Alan Robertson, Kenneth Allen Savin, Less «
Applicant Eli Lilly And Company

Image result for Eli Lilly And Company

Image result for tradipitant


Condensation of 2-chloropyridine with thiophenol  in the presence of K2CO3 in DMF at 110ºC yields sulfide intermediate,

which is then oxidized by means of NaOCl in AcOH to give 2-(benzenesulfonyl)pyridine.

This is treated with (iPr)2NH and n-BuLi in THF at -60 to -70°C and subsequently couples with 2-chlorobenzaldehyde  in THF at -60 to -70°C to furnish (2-(phenylsulfonyl)pyridin-3-yl)-(2-chlorophenyl)methanone.

Ketone  couples with the enolate of 4-acetylpyridine (formed by treating 4-acetylpyridine (VII) with t-BuOK in DMSO) in the presence of LiOH in DMSO and subsequently is treated with PhCOOH in iPrOAc to give rise to pyridine benzoate derivative.

This finally couples with 1-azidomethyl-3,5-bistrifluoromethylbenzene  (obtained by treating 3,5-bis(trifluoromethyl)benzylchloride with NaN3 ini DMSO) in the presence of K2CO3 in t-BuOH to afford the title compound Tradipitant.

Tradipitant (VLY-686 or LY686017) is an experimental drug that is a neurokinin 1 antagonist. It works by blocking substance P, a small signaling molecule. Originally, this compound was owned by Eli Lilly and named LY686017. VLY-686 was purchased by Vanda Pharmaceuticals from Eli Lilly and Company in 2012.[1] Vanda Pharmaceuticals is a U.S. pharmaceutical company that as of November 2015 only has 3 drugs in their product pipeline: tasimelteon, VLY-686, and iloperidone.[2]

Tachykinins are a family of peptides that are widely distributed in both the central and peripheral nervous systems. These peptides exert a number of biological effects through actions at tachykinin receptors. To date, three such receptors have been characterized, including the NK-1 , NK-2, and NK-3 subtypes of tachykinin receptor.

The role of the NK-1 receptor subtype in numerous disorders of the central nervous system and the periphery has been thoroughly demonstrated in the art. For instance, NK-1 receptors are believed to play a role in depression, anxiety, and central regulation of various autonomic, as well as cardiovascular and respiratory functions. NK- 1 receptors in the spinal cord are believed to play a role in pain transmission, especially the pain associated with migraine and arthritis. In the periphery, NK-1 receptor activation has been implicated in numerous disorders, including various inflammatory disorders, asthma, and disorders of the gastrointestinal and genitourinary tract.

There is an increasingly wide recognition that selective NK-1 receptor antagonists would prove useful in the treatment of many diseases of the central nervous system and the periphery. While many of these disorders are being treated by new medicines, there are still many shortcomings associated with existing treatments. For example, the newest class of anti-depressants, selective serotonin reuptake inhibitors (SSRIs), are increasingly prescribed for the treatment of depression; however, SSRIs have numerous side effects, including nausea, insomnia, anxiety, and sexual dysfunction. This could significantly affect patient compliance rate. As another example, current treatments for chemotherapy- induced nausea and emesis, such as the 5-HT3receptor antagonists, are ineffective in managing delayed emesis. The development of NK-1 receptor antagonists will therefore greatly enhance the ability to treat such disorders more effectively. Thus, the present invention provides a class of potent, non-peptide NK-1 receptor antagonists, compositions comprising these compounds, and methods of using the compounds.



It is being investigated by Vanda Pharmaceuticals for chronic pruritus (itchiness) in atopic dermatitis. In March 2015, Vanda announced positive results from a Phase II proof of concept study.[3] A proof of concept study is done in early stage clinical trials after there have been promising preclinical results. It provides preliminary evidence that the drug is active in humans and has some efficacy.[4]


VLY-686 reduced alcohol craving in recently detoxified alcoholic patients as measured by the Alcohol Urge Questionnaire.[5] In a placebo controlled clinical trial of recently detoxified alcoholic patients, VLY-686 significantly reduced alcohol craving as measured by the Alcohol Urge Questionnaire. It also reduced the cortisol increase seen after a stress test compared to placebo. The dose given was 50 mg per day.

Social anxiety disorder

In a 12-week randomized trial of LY68017 in 189 patients with social anxiety disorder, 50 mg of LY68017 did not provide any statistically significant improvement over placebo.[6]





The compound {2-[l-(3,5-bis-trifluoromethyl-benzyl)-5-pyridin-4-yl-lH-[l,2,3]triazol-4-yl]- pyridin-3-yl}-(2-chlorophenyl)-methanone, depicted below as the compound of Formula I, was first described in PCT published application WO2003/091226.

Figure imgf000003_0001


Because the compound of Formula I is an antagonist of the NK-I subtype of tachykinin receptor, it is useful for the treatment of disorders associated with an excess of tachykinins. Such disorders include depression, including major depressive disorder; anxiety, including generalized anxiety disorder, panic disorder, obsessive compulsive disorder, and social phobia or social anxiety disorder; schizophrenia and other psychotic disorders, including bipolar disorder; neurodegenerative disorders such as dementia, including senile dementia of the Alzheimer’s type or Alzheimer’s disease; disorders of bladder function such as bladder detrusor hyper-reflexia and incontinence, including urge incontinence; emesis, including chemotherapy-induced nausea and acute or delayed emesis; pain or nociception; disorders associated with blood pressure, such as hypertension; disorders of blood flow caused by vasodilation and vasospastic diseases, such as angina, migraine, and Reynaud’s disease; hot flushes; acute and chronic obstructive airway diseases such as adult respiratory distress syndrome, bronchopneumonia, bronchospasm, chronic bronchitis, drivercough, and asthma; inflammatory diseases such as inflammatory bowel disease; gastrointestinal disorders or diseases associated with the neuronal control of viscera such as ulcerative colitis, Crohn’s disease, functional dyspepsia, and irritable bowel syndrome (including constipation-predominant, diarrhea- -?-

predominant, and mixed irritable bowel syndrome); and cutaneous diseases such as contact dermatitis, atopic dermatitis, urticaria, and other eczematoid dermatitis.

In PCT published application, WO2005/042515, novel crystalline forms of the compound of Formula I, identified as Form IV and Form V, are identified. Also described in WO2005/042515 is a process for preparation of the compound of Formula I, comprising reacting (2-chlorophenyl)-[2-(2- hydroxy-2-pyridin-4-yl-vinyl)pyridin-3-yl]methanone or a phosphate salt thereof with l-azidomethyl-3,5- bistrifluoromethylbenzene in the presence of a suitable base and a solvent. Use of this procedure results in several shortcomings for synthesis on a commercial scale. For example, use of the solvent DMSO, with (2- chlorophenyl)-[2-(2-hydroxy-2-pyridin-4-yl-vinyl)pyridin-3-yl]methanone phosphate, requires a complex work-up that has a propensity to emulsify. This process also requires extraction with CH2CI2, the use of which is discouraged due to its potential as an occupational carcinogen, as well as the use of MgSC>4 and acid-washed carbon, which can generate large volumes of waste on a commercial scale. Conducting the reaction with (2-chlorophenyl)-[2-(2-hydroxy-2-pyridin-4-yl-vinyl)pyridin-3-yl]methanone in isopropyl alcohol, as also described in WO2005/042515, is also undesirable due to the need to incorporate a free base step. Furthermore, variable levels of residual l-azidomethyl-3,5-bistrifluoromethylbenzene, a known mutagen, are obtained from use of the procedures described in WO2005/042515.

An improved process for preparing the compound of Formula I would control the level of 1- azidomethyl-3,5-bistrifluoromethylbenzene impurity, and improve the yield. We have discovered that use of the novel salt, (2-chlorophenyl)-[2-(2-hydroxy-2-pyridin-4-yl-vinyl)pyridin-3-yl]methanone benzoate, as well as use of tert-butanol as the reaction solvent, improves reaction times and final yield, and decreases impurities in the final product. In addition, a novel process for the preparation of (2-chlorophenyl)- [2-(2- hydroxy-2-pyridin-4-yl-vinyl)pyridin-3-yl]methanone benzoate, in which a pre-formed enolate of 4-acetyl pyridine is added to (2-phenylsulfonyl-pyridine-3-yl)-(2-chlorophenyl)methanone, results in an overall improved yield and improved purity, and is useful on a commercial scale.


Example 1 {2-[l-(3,5-bistrifluoromethylbenzyl)-5-pyridin-4-yl-lH-[l,2,3]triazol-4-yl]-pyridin-3-yl}-(2-chlorophenyl)- methanone (Form IV)

Figure imgf000005_0001

Suspend (2-chlorophenyl)-[2-(2-hydroxy-2-pyridin-4-yl-vinyl)pyridin-3-yl] methanone benzoate (204.7 g; 1.04 equiv; 445 mmoles) in t-butanol (614 mL) and treat the slurry with potassium carbonate (124.2 g; 898.6 mmoles). Heat to 7O0C with mechanical stirring for 1 hour. Add l-azidomethyl-3,5- bistrifluoromethylbenzene (115.6 g; 1.00 equiv; 429.4 mmoles) in a single portion, then heat the mixture to reflux. A circulating bath is used to maintain a condenser temperature of 3O0C. After 18 hours at reflux, HPLC reveals that the reaction is complete (<2% l-azidomethyl-3,5-bistrifluoromethylbenzene remaining). The mixture is cooled to 7O0C, isopropanol (818 mL) is added, then the mixture is stirred at 7O0C for 1 hour. The mixture is filtered, and the waste filter cake is rinsed with isopropanol (409 mL). The combined filtrate and washes are transferred to a reactor, and the mechanically stirred contents are heated to 7O0C. To the dark purple solution, water (1.84 L) is added slowly over 35 minutes. The solution is cooled to 6O0C, then stirred for 1 hour, during which time a thin precipitate forms. The mixture is slowly cooled to RT, then the solid is filtered, washed with 1 : 1 isopropanol/water (614 mL), subsequently washed with isopropanol (410 mL), then dried in vacuo at 450C to produce 200.3 g of crude {2-[l-(3,5- bistrifluoromethylbenzyl)-5-pyridin-4-yl-lH-[l,2,3]triazol-4-yl]-pyridin-3-yl}-(2-chlorophenyl)-methanone as a white solid. Crude {2-[l-(3,5-bistrifluoromethylbenzyl)-5-pyridin-4-yl-lH-[l,2,3]triazol-4-yl]-pyridin- 3-yl}-(2-chlorophenyl)-methanone (200.3 g) and isopropyl acetate (600 mL) are charged to a 5L 3-neck jacketed flask, then the contents heated to 750C. After dissolution is achieved, the vessel contents are cooled to 550C, then the solution polish filtered through a 5 micron filter, and the filter rinsed with a volume of isopropyl acetate (200 mL). After the polish filtration operation is complete, the filtrates are combined, and the vessel contents are adjusted to 5O0C. After stirring for at least 15 minutes at 5O0C, 0.21 grams of {2-[l-(3,5-bistrifluoromethylbenzyl)-5-pyridin-4-yl-lH-[l,2,3]triazol-4-yl]-pyridin-3-yl}-(2- chlorophenyl)-methanone Form IV seed (d90 = 40 microns) is added, and the mixture stirred at 5O0C for at least 2 h. Heptanes (1.90 L) are then added over at least 2 h. After the heptanes addition is completed, the slurry is stirred for an hour at 5O0C, cooled to 230C at a rate less then 2O0C per hour, then aged at 230C for an hour prior to isolation. The mixture is then filtered in portions through the bottom outlet valve in the reactor into a 600 mL filter. The resulting wetcake is washed portionwise with a solution containing heptanes (420 mL) and isopropyl acetate (180 mL), which is passed directly through the 5L crystallization vessel. The wetcake is blown dry for 5 minutes with nitrogen, then transferred to a 500 mL plastic bottle. The product is dried at 5O0C for 4 h. to produce 190.3g of pure {2-[l-(3,5- bistrifluoromethylbenzyl)-5-pyridin-4-yl-lH-[l,2,3]triazol-4-yl]-pyridin-3-yl}-(2-chlorophenyl)- methanone, Form IV in 75.0% yield with 100% purity, as determined by HPLC analysis. Particle size is reduced via pin or jet mill. 1H NMR (400 MHz, CDCl3): 5.46 (s, 2H); 7.19 (m, 5H); 7.36 (dd, IH, J = 4.9, 7.8); 7.45 (s, 2H); 7.59 (m, IH); 7.83 (s, IH); 7.93 (dd, IH, J = 1.5, 7.8); 8.56 (dd, IH, J= 1.5, 4.9); 8.70 (d, 2H, J= 5.9).

Preparation 1-A (2-chlorophenyl)-[2-(2-hydroxy-2-pyridin-4-yl-vinyl)pyridin-3-yl]methanone benzoate Charge powdered KOfBu (221.1 g, 1.93 moles, 1.40 eq.) to Reactor A, then charge DMSO (2 L) at

250C over 10 min. The KOfBu/DMSO solution is stirred for 30 min at 230C, then a solution of 4-acetyl pyridine (92 mL, 2.07 moles, 1.50 eq) in DMSO (250 mL) is prepared in reactor B. The contents of reactor B are added to Reactor A over 10 minutes, then the Reactor A enolate solution is stirred at 230C for Ih. In a separate 12-L flask (Reactor C), solid LiOH (84.26 g, 3.45 moles, 2.0 eq) is poured into a mixture of (2- phenylsulfonyl-pyridin-3-yl)-(2-chlorophenyl)methanone (500.0 g, 1.34 moles, 1.0 eq) and DMSO (2L), with stirring, at 230C. The enolate solution in reactor A is then added to Reactor C over a period of at least 15 minutes, and the red suspension warmed to 4O0C. The reaction is stirred for 3h, after which time HPLC analysis reveals less than 2% (2-phenylsulfonyl-pyridin-3-yl)-(2-chlorophenyl)methanone. Toluene (2.5 L) is charged, and the reactor temperature cooled to 3O0C. The mixture is quenched by addition of glacial acetic acid (316 mL, 5.52 moles, 4.0 eq), followed by 10 % NaCl (2.5 L). The biphasic mixture is transferred to a 22-L bottom-outlet Morton flask, and the aqueous layer is removed. The aqueous layer is then extracted with toluene (750 mL). The combined organic layers are washed with 10 % NaCl (750 mL), then concentrated to 4 volumes and transferred to a 12-L Morton flask and rinsed with isopropyl acetate (4 vol, 2 L). The opaque amber solution is warmed to 75 degrees to 750C over 40 min. Benzoic acid (171. Ig, 1.34 moles, 1.0 eq) is dissolved in hot isopropyl acetate (1.5 L), and charged to the crude free base solution over at least 30 min. The crude solution containing benzoate salt is stirred for 0.5 h at 750C then cooled to 23 0C. When solids are first observed, the cooling is stopped and the mixture is aged for an hour at the temperature at which crystals are first observed. Alternatively, if seed crystal is available, the mixture may be seeded with (2-chlorophenyl)-[2-(2-hydroxy-2-pyridin-4-yl-vinyl)pyridin-3-yl]methanone benzoate (2.25g) at 750C, followed by stirring for 0.5 h at 750C, then cooling to 230C over at least 1.5 h. The mixture is then cooled to <5 0C, then filtered through paper on a 24cm single-plate filter. The filtercake is then rinsed with cold z-PrOAc (750 mL) to produce granular crystals of bright orange-red color. The wet solid is dried at 550C to produce 527.3 g (83% yield) with 99.9% purity. (2-chlorophenyl)-[2-(2-hydroxy-2- pyridin-4-yl-vinyl)pyridin-3-yl]methanone benzoate. Anal. Calcd. for C26Hi9N2ClO4: C, 68.05; H, 4.17; N, 7.13. Found: C, 67.89; H, 4.15; N 6.05. HRMS: calcd for C19H13ClN2O2, 336.0666; found 336.0673.

The synthesis of(2-chlorophenyl)-[2-(2-hydroxy-2-pyridin-4-yl-vinyl)pyridin-3-yl]methanone benzoate proceeds optimally when the potassium enolate of 4-acetyl pyridine is pre-formed using KOfBu in DMSO. Pre-formation of the enolate allows the SNAR (nucleophilic aromatic substitution) reaction to be performed between room temperature and 4O0C, which minimizes the amount of degradation. Under these conditions, the SNAR is highly regioselective, resulting in a ratio of approximately 95:5 preferential C – acylation. In all cases, less polar solvents such as THF or toluene, or co-solvents of these solvents mixed with DMSO, results in a substantial increase of acylation at the oxygen in the SNAR, and leads to a lower yield of product. This is a substantial improvement over the procedures described in WO2005/042515 for synthesis of the free base or the phosphate salt, in which the SNAR is performed at 60-700C, resulting in a substantial increase in chemical impurity. Using the conditions described in WO2005/042515, when scaled to 2kg, results in maximum yields of 55%, with sub-optimal potency. In comparison, the improved conditions described herein can be run reproducibly from 0.4 to 2kg scale to give yields of 77-83%, with >99% purity. In addition, the reaction can be held overnight at 4O0C with minimal degradation, whereas holding the reaction for 1 h past completion at 60-70°C results in substantial aromatized impurity. The reaction may also be performed using sodium tert-amylate as the base, in combination with an aprotic solvent, such as DMSO or DMF.

The title compound exists as a mixture of tautomers and geometric isomers. It is understood that each of these forms is encompassed within the scope of the invention.

Figure imgf000008_0001

Preparation 1-B

(2-chlorophenyl)-[2-(2-hydroxy-2-pyridin-4-yl-vinyl)pyridin-3-yl]methanone toluate The procedure described in Preparation 1-A is followed, with the following exception. Solid toluic acid (1.0 eq) is added to the crude free base solution at 550C, then the solution cooled to 45 0C. The solution is stirred for one hour at 45 0C, then slowly cooled to 23 0C. When solids are first observed, the cooling is stopped and the mixture is aged for an hour at the temperature at which crystals are first observed. Alternatively, if seed crystal is available, the mixture may be seeded, aged for 3 h at 450C , then cooled to O0C over 4 h. The isolation slurry is filtered, and the wetcake washed with MeOH (3 volumes). The wetcake is dried at 5O0C to provide 14.0 g (76.4%) of (2-chlorophenyl)-[2-(2-hydroxy-2-pyridin-4-yl- vinyl)pyridin-3-yl]methanone toluate as a light red powder.

As with the benzoate salt, the toluate salt can also exist as a mixture of tautomers and geometric isomers, each of which is encompassed within the scope of the invention. (2-chlorophenyl)-[2-(2-hydroxy- 2-pyridin-4-yl-vinyl)pyridin-3-yl]methanone toluate . 13C NMR (125 MHz,DMS0-d6) δ 194.5, 167.8, 167.4, 155.5, 150.7 (2C), 147.4, 144.0, 143.4, 142.7, 138.6, 133.0, 130.8, 130.7, 130.5, 129.8(2C), 129.5(2C), 128.5, 128.0, 127.9, 119.9 (2C), 118.6, 92.6, 21.5.

Preparation 1-C


A solution of 1.3 eq of diisopropylamine (based on 2-benzenesulfonyl pyridine) in 5 volumes of THF in a mechanically stirred 3 -necked flask is cooled to -70 to -75 0C. To this solution is added 1.05 eq of w-butyllithium (1.6M in hexanes) at such a rate as to maintain the temperature below -6O0C. The light yellow solution is stirred at -60 to -70 0C for 30 minutes. Once the temperature has cooled back down to – 60 to -650C, 1.0 eq of 2-benzene-sulfonyl pyridine, as a solution in 3 volumes of THF, is added at the fastest rate that will maintain the reaction temperature under -6O0C. A yellow suspension forms during the addition that becomes yellow-orange upon longer stirring. This mixture is stirred for 3 hours at -60 to – 750C, and then 1.06 eq of 2-chlorobenzaldehyde, as a solution in 1 volume of THF, is added dropwise at a sufficient rate to keep the temperature under -55 0C. The suspension gradually turns orange-red, thins out, and then becomes a clear red solution. The reaction mixture is allowed to stir at -60 to -7O0C for 1 hour, 3N aqueous HCl (7 volumes) is added over 20-30 minutes, and the temperature is allowed to exotherm to 0-100C. The color largely disappears, leaving a biphasic yellow solution. The solution is warmed to at least 1O0C, the layers are separated, and the aqueous layer is back-extracted with 10 volumes of ethyl acetate. The combined organic layers are washed with 10 volumes of saturated sodium bicarbonate solution and concentrated to about 2 volumes. Ethyl acetate (10 volumes) is added, and the solution is once again concentrated to 2 volumes. The thick solution is allowed to stand overnight and is taken to the next step with no purification of the crude alcohol intermediate. The crude alcohol intermediate is transferred to a 3 -necked flask with enough ethyl acetate to make the total solution about 10 volumes. The yellow solution is treated with 3.2 volumes of 10% aqueous (w/w) potassium bromide, followed by 0.07 eq of 2,2,6,6-Tetramethylpiperidine-N-oxide (TEMPO). The orange mixture is cooled to 0-50C and treated with a solution of 1.25 eq of sodium bicarbonate in 12% w/w sodium hypochlorite (9 volumes) and 5 volumes of water over 30-60 minutes while allowing the temperature to exotherm to a maximum of 2O0C. The mixture turns dark brown during the addition, but becomes yellow, and a thick precipitate forms. The biphasic light yellow mixture is allowed to stir at ambient temperature for 1-3 hours, at which time the reaction is generally completed. The biphasic mixture is cooled to 0-50C and stirred for 3 hours at that temperature. The solid is filtered off, washed with 4 volumes of cold ethyl acetate, followed by 4 volumes of water, and dried in vacuo at 450C to constant weight. Typical yield is 80-83% with a purity of greater than 98%. 1H NMR (600 MHz, CDCl3-^) δ ppm 7.38 (td, ./=7.52, 1.28 Hz, 1 H) 7.47 (dd, ./=7.80, 1.30 Hz, 1 H) 7.51 (td, ./=7.79, 1.60 Hz, 1 H) 7.51 (t, ./=7.89 Hz, 2 H) 7.50 – 7.54 (m, J=7.75, 4.63 Hz, 1 H) 7.60 (t, J=7.43 Hz, 1 H) 7.73 (dd, J=7.75, 1.60 Hz, 1 H) 7.81 (dd, J=7.79, 1.56 Hz, 1 H) 8.00 (dd, ./=8.44, 1.10 Hz, 2 H) 8.76 (dd, ./=4.63, 1.61 Hz, 1 H).

Preparation 1-D 1 -azidomethyl-3,5-bistrifluoromethyl-benzene

Sodium azide (74.3 g, 1.14 mol) is suspended in water (125 mL), then DMSO (625 mL) is added. After stirring for 30 minutes, a solution consisting of 3,5-Bis(trifluoromethyl)benzyl chloride (255.3 g, 0.97 moles) and DMSO (500 mL) is added over 30 minutes. (The 3,5-Bis(trifluoromethyl)benzyl chloride is heated to 350C to liquefy prior to dispensing (MP = 30-320C)). The benzyl chloride feed vessel is rinsed with DMSO (50 mL) into the sodium azide solution, the mixture is heated to 4O0C, and then maintained for an hour at 4O0C, then cooled to 230C.

In Process Analysis: A drop of the reaction mixture is dissolved in d6-DMSO and the relative intensities of the methylene signals are integrated (NMR verified as a 0.35% limit test for 3,5- Bis(trifluoromethyl)benzyl Chloride). Work-up: After the mixture reaches 230C , it is diluted with heptanes (1500 mL), then water (1000 mL) is added, and the mixture exotherms to 350C against a jacket setpoint of 230C. The aqueous layer is removed (-2200 mL), then the organic layer (approximately 1700 mL) is washed with water (2 X 750 mL). The combined aqueous layers (-3700 mL) are analyzed and discarded.

The solvent is then partially removed via vacuum distillation with a jacket set point of 850C, pot temperature of 60-650C and distillate head temperature of 50-550C to produce 485g (94.5% yield) of 51 Wt% solution title compound as a clear liquid. Heptanes can be either further removed by vacuum distillation or wiped film evaporation technology. 1H NMR (400 MHz, CDCl3): 4.58 (s, 2H); 7.81 (s, 2H); 7.90 (s, IH).

Preparation 1-E 2-benzene-sulfonyl pyridine Charge 2-chloropyridine (75 mL, 790 mmol), thiophenol (90 mL, 852 mmol), and DMF (450 mL) to a 2L flask. Add K2CO3 (134.6 g, 962 mmol), then heat to HO0C and stir for 18 hours. Filter the mixture, then rinse the waste cake with DMF (195 mL). The combined crude sulfide solution and rinses are transferred to a 5-L flask, and the waste filtercake is discarded. Glacial acetic acid (57 mL, 995 mmol) is added to the filtrate, then the solution is heated to 4O0C, and 13 wt % NaOCl solution (850 mL, 1.7 mol) is added over 2 hours. After the reaction is complete, water (150 mL) is added, then the pH of the mixture adjusted to 9 with 20 % (w/v) NaOH solution (250 mL). The resulting slurry is cooled to <5 0C, stirred for 1.5 h, then filtered, and the cake washed with water (3 x 200 mL). The product wetcake is dried in a 550C vacuum oven to provide 2-benzene-sulfonyl pyridine (149 g, 676 mmol) in 86 % yield: 1H NMR (500 MHz, CDCl3) δ 8.66 (d, J = 5.5 Hz, IH), 8.19 (d, J = 1.1 Hz, IH), 8.05 (m, 2H), 7.92 (ddd, J= 9.3, 7.7, 1.6 Hz, IH), 7.60 (m, IH), 7.54 (m, 2H), 7.44 (m, IH); IR (KBr) 788, 984, 1124, 1166, 1306, 1424, 1446, 1575, 3085 cm“1; MS (TOF) mlz 220.0439 (220.0427 calcd for C11H10NO2S, MH); Anal, calcd for C11H9NO2S: C, 60.26; H, 4.14; N, 6.39; S, 14.62. Found: C, 60.40; H, 4.02; N, 6.40; S, 14.76.

As noted above, use of the improved process of the present invention results in an improved habit of the crystalline Form IV compound of Formula I. The improved habit reduces surface area of the crystal, improves the filtration, and washing, and improves the efficiency of azide mutagen rejection. These improvements are described in greater detail below.

In patent application WO2005/042515, the polish filtration is carried out in 7 volumes (L/kg) of isopropanol near its boiling point (65-83 0C), a process that is difficult and hazardous to execute in commercial manufacturing because of the high risk of crystallization on the filter and/or vessel transfer lines due to supersaturation. In the preferred crystallization solvent, isopropyl acetate, the polish filtration is conducted in four volumes of isopropyl acetate at temperatures from 45 to 55 0C. This temperature range is 35 to 45 0C lower than the boiling point of isopropyl acetate, which provides a key safety advantage.


WO 2005042515


WO 2017031215


Example 1: Preparation of Compound (I) via Negishi Coupling Route

Example 1 provides a scheme including preparations 1A-1D, described below, for the synthesis of the compound of Formula (I) and intermediates used in the route. An overview of the scheme is as follows:

80 on ma s ale

Example 1A: Preparation of Compound (I)

Zinc dust (200 mg, 3.06 mmol) combined with 2.0 mL of dimethylformamide was treated with 0.010 mL of 1,2-dibromoethane and heated to 65°C for 3 minutes. The mixture was cooled to ambient temperature and treated with 0.010 mL of trimethylsilyl chloride. After 5 minutes, 1.26 mL of 1M zinc chloride in diethyl ether was added to the mixture followed by Compound (Ila) (600 mg, 1.20 mmol). The mixture was heated to 65°C and further treated with 0.020 mL each of 1,2-dibromoethane and trimethylsilyl chloride. After 2.5 hours, via HPLC chromatogram, the reaction showed some formation of the zincate and was allowed to stir at ambient temperature for 16 hours. At this time

tetrakis(triphenylphosphine)palladium(0) (70 mg, 0.06 mmol), Compound (Ilia) (357 mg, 1.20 mmol) were added to the reaction and the mixture heated to 65°C. HPLC analysis showed the formation of Compound (I) in the reaction.

IB: Preparation of Comp

To a solution of Compound (IV) (8.00 g, 18 mmol) in 40 mL of 1,2-dichloroethane was added a solution of iodine monochloride (10.7 g, 65.9 mmol) in 40 mL of 1,2-dichloroethane resulting in a slurry. The slurry was heated to 75°C for 4 hours then cooled to ambient temperature. The solids were collected by filtration, washed with heptane, then combined with 90 mL of ethyl acetate and 80 mL of saturated sodium thiosulfate solution. The organic phase was washed with saturated sodium chloride solution and dried with sodium sulfate. The mixture was concentrated to yield 7.80 g (87%) of Compound (Ila) as a yellow solid. The product could be further purified by silica gel chromatography. Thus 2.0 g of yellow solid was dissolved in dichloromethane and charged onto a silica gel column. The product was eluted using tert-butyl methyl ether to provide 1.87 g (93% recovery) of Compound (Ila) as a white powder. Analytical data: Iodine monochloride complex: ¾ NMR (500 MHz, DMSO-de) δ 8.80 (2 H), 8.05 (1 H), 7.77 (2 H), 7.59 (2 H), 5.86 (2 H).

Uncomplexed: ¾ NMR (500 MHz, DMSO-de) δ 8.71 (2 H), 8.03 (1 H), 7.74 (2 H), 7.44 (2 H), 5.86 (2 H).

It was observed that the iodination proceeded smoothly as a suspension in 1,2-dichloroethane with IC1 (4.0 equiv) at 75°C. An ICl-Compound (Ila) complex was initially isolated by filtration. Compound (Ila) was then obtained in approximately 85% yield by treatment of the ICl-Compound (Ila) complex with sodium thiosulfate. This protocol provided a viable means of isolation of Compound (Ila) without the use of DMF.

Example 1C: Preparation of silyl substituted triazole (Compound IV)

A mixture of Compound (V) (8.07 g, 30.0 mmol) and Compound (VI) (5.12 g, 29.2 mmol) was heated to 100°C for 18 hours. To the mixture was added 40 mL of heptane and the reaction was allowed to cool with rapid stirring. After 1 hour the solids were collected by filtration and washed with heptane then dried to 9.30 g (72%) of Compound (IV) as a tan solid. Analytical data: ¾ NMR (500 MHz, DMSO-de) δ 8.66 (2 H), 8.04 (1 H), 7.67 (2 H), 7.32 (2 H), 5.72 (2 H), 0.08 (9 H).

It was further found that combining Compound (V) and Compound (VI) (neat) and heating at 95 – 105°C afforded a 92: 8 mixture of regioisomers as shown below:

Crystallization of the mixture from heptane afforded Compound (IV) in 62-72% yield, thus obviating the need for chromatography to isolate Compound (IV).

Example ID: Preparation of starting material Compound (VI)

Zinc bromide (502 g, 2.23 mole) was added in approximately 100 g portions to 2.0 L of tetrahydrofuran cooled to between 0 and 10°C. To this cooled solution was added 4-bromopyridine hydrochloride (200 g, 1.02 mol), triphenylphosphine (54 g, 0.206 mol), and palladium (II) chloride (9.00 g, 0.0508 mol). Triethylamine (813 g, 8.03 mol) was then added at a rate to maintain the reaction temperature at less than 10°C, and finally

trimethylsilylacetylene (202 g, 2.05 mol) was added. The mixture was heated to 60°C for 4.5 hours. The reaction was cooled to -5°C and combined with 2.0 L of hexanes and treated with 2 L of 7.4 M NH4OH. Some solids were formed and were removed as much as possible with the aqueous phase. The organic phase was again washed with 2.0 L of 7.4 M NH4OH, followed by 2 washes with 500 mL of water, neutralized with 1.7 L of 3 M hydrochloric acid, dried with sodium sulfate, and concentrate to a thick slurry. The slurry was combined with 1.0 L of hexanes to give a precipitate. The precipitate was removed by filtration and the filtrate was concentrated to 209 g of dark oil. The product was purified by distillation (0.2 torr, 68°C) to give 172 g (96%) of Compound (VI) as colorless oil. Analytical data: ¾ NMR (500 MHz, DMDO-de) δ 8.57 (2 H), 7.40 (2 H), 0.23 (9 H).

EXAMPLE 2 – Preparation of Compound (Ilia)

Example 2 provides a morpholine amide route for the synthesis of Compound (Ilia). In this approach, morpholine amide (Compound VII) was prepared from 2-chlorobenzoyl chloride (Preparation 2A). Metallation of 2-bromopyridine with LDA (1.09 equiv.) in THF at -70°C followed by addition of (Compound VII) afforded Compound (Ilia) in 37% yield after crystallization from IP A/heptane (Preparation 2B). This sequence provides a direct route to Compound (Ilia), and a means to isolate Compound (Ilia) without the use of

chromatography. Compound (Ilia) may then be used to form Compound (I) as shown in Example 1A above (Preparation 2C).

Preparation 2A: Preparation of Compound (VII)

Toluene (1.5 L) was added to Compound (IX) (150 g, 0.86 mol) and cooled to 10°C. Morpholine (82 mL, 0.94 mol) was added to the clear solution over 10 minutes. The resulting white slurry was stirred for 20 minutes then pyridine (92 mL, 1.2 mol) was added dropwise over 20 minutes. The cloudy white mixture was stirred in a cold bath for 1 hour. Water (600 mL) was added in a single portion and the cold bath removed. The mixture was stirred for 20 minutes and the layers are separated. The organic layer was washed with a mixture of 1 N HC1 and water (2: 1, 500 mL:250 mL). The pH of the aqueous layer was ~ 2. The organic layer was washed with a mixture of saturated NaHCCb and water (1 : 1, 100 mL: 100 mL). The pH of the aqueous layer was ~ 9. The layers were separated. The organic layer was concentrated in vacuo to an oil. The oil was dissolved in IPA (70 mL) and heated at 60°C for 30 min. The clear solution was allowed to cool to 30°C, then heptane (700 mL, 4.7 v) was added dropwise. The resulting slurry was stirred at RT for 2 hours then cooled to 0°C for 1 hour. The slurry was filtered at RT, washed with heptane then dried under vacuum at 30°C overnight. Compound (VII) (156.2 g, 81%) was obtained as a white solid. Analytical data: ¾ NMR (500 MHz, CDCh) δ 7.42-7.40 (m, 1 H), 7.35-7.29 (m, 3 H), 3.91-3.87 (m, 1 H), 3.80-3.76 (m, 3 H), 3.71 (ddd, J= 11.5, 6.8, 3.3 Hz, 1 H), 3.60 (ddd, J = 11.2, 6.4, 3.4 Hz, 1 H), 3.28 (ddd, J= 13.4, 6.3, 3.2 Hz, 1 H), 3.22 (ddd, J= 13.7, 6.8, 3.3 Hz, 1 H); LRMS (ES+) calcd for CnHi3F6ClN02 (M+H)+ 226.1, found 225.9 m/z.

Preparation 2B: Preparation of Compound (Ilia)

THF (75 mL) was added to diisopropyl amine (4.9 mL, 34.8 mmol) and cooled to a

temperature of -70°C under N2 atmosphere. 2.5 M w-BuLi in hexanes (13.9 mL, 34.8 mmol) was added in a single portion (a 30-40°C exotherm) to the clear solution and cooled back to -70°C. Compound (VIII) (5.0 g, 31.6 mmol) was added neat to the LDA solution (a 2 to 5°C exotherm) followed by a THF (10 mL) rinse, keeping T< -65°C. This clear yellow solution was stirred at -70°C for 15 min. Compound (VII) (7.1 g, 31.6 mmol) in THF (30 mL) was added keeping T< -65°C. The resulting clear orange solution was stirred at -70°C for 3 hours. MeOH (3 mL) was added to quench reaction mixture and the cold bath was removed. 5 N HC1 (25 mL) was added to the reaction solution. MTBE (25 mL) was added, and the layers were separated. The organic layer was washed with water (25 mL X 2). The organic layer was dried over MgS04 and filtered. The organic layer was concentrated in vacuo to an orange oil. The oil was dissolved in IPA (15 mL, 3 vol) at ambient temperature. Heptane (25 mL) was added dropwise and the resulting slurry was stirred at RT for 1 hour. The slurry was cooled to 0°C for 1 hour and filtered. The filter cake was rinsed with chilled heptane (20 mL) and dried under vacuum at 30°C overnight. Compound (Ilia) (4.25 g, 45%) was obtained as a yellow solid.

Several reactions were run at different temperatures and with different addition rates of Compound (VII). If the reaction temperature was maintained below -65°C and Compound (VII) was added in <5 min, it was found that the reaction worked well. If the temperature was increased and/or the addition time of Compound (VII) was increased, then yields suffered, and the work-up was complicated by emulsions.

Preparation 2C: Preparation of Compound (I)

Compound (Ilia) may then reacted with Compound (Ila) to produce Compound (I) as shown in Preparation 1A.


Example 3 describes a new route for the synthesis of an intermediate free base, which may be used to form Compound (I) as described further below.

Example 3A: Preparation of starting material (Compound X) from 2-Chloronicotinonitrile

A mixture of NaH (40.0 g, 1 mol, 60% dispersion in mineral oil) and 2-chloronicotinonitrile (69.3 g, 500 mmol) in THF (1 L) was heated to reflux. A solution of 4-acetylpyridine (60.6 g, 500 mmol) in THF (400 mL) was added over a period of 40 min. The resulting dark brown mixture was stirred at reflux for ~ 2 h. The heating mantle was then removed, and AcOH (58 mL, 1 mol) was added. EtOAc (1 L) and H2O (1 L) were then added, and the layers were separated. The organic layer was concentrated to afford an oily solid. CH3CN (500 mL) was added, and the mixture was stirred for 30 min. H2O (1 L) was then added. The mixture was stirred for 1 h then filtered. The solid was rinsed with 2: 1

CH3CN-H2O (900 mL) and hexanes (400 mL) then dried under vacuum at 45°C overnight to afford 61.4 g (55% yield) of Compound (X) as yellow solid. Compound (X) exists as an approximate 95:5 enol-ketone mixture in CDCI3. Analytical data for enol: IR (CHCI3): 3024, 2973, 2229, 1631, 1597, 1579, 1550, 1497; ¾ NMR (500 MHz, CDCI3) δ 8.69 (dd, J= 4.4,

1.7 Hz, 2H), 8.55 (dd, J = 5.2, 1.8 Hz, 1H), 7.97 (dd, J= 7.9, 1.8 Hz, 1H), 7.70 (dd, J= 4.6, 1.5 Hz, 2H, 7.17 (dd, J = 7.8, 5.0 Hz, 1H), 6.59 (s, 1H); LRMS (ES+) calcd for C13H10N3O (M+H)+ 224.1, found 224.0 m/z.

Preparation 3B: Preparation of Compound (XI)

Preparation 3B(1):

(X) (XI)

Compound (XI) may be prepared using Compound (X).

Preparation 3B(2):

Alternatively, the following procedure for the conversion of nitrile into an acid which may also yield compound (XI). A mixture of Compound (X) (1 eq) and NaOH (1.5 eq) in 1 : 1 fhO-EtOH (3.5 mL/g of Compound (X)) was heated at 65°C overnight. The reaction mixture was cooled to RT then added to CH2C12 (12.5 mL/g of Compound (X)) and H20 (12.5 mL/g of Compound (X)). Cone. HC1 (2.5 mL/g of Compound (X)) was then added, and the layers were separated. The aqueous layer was extracted with CH2CI2 (10 mL/g of Compound (X)). The combined organic extracts were washed with H2O (12.5 ml/g of Compound (X)), dried (MgS04), filtered and concentrated to afford Compound (XI).

Preparation 3C

Compound Compound (XI) may then be converted into a Stage C intermediate free base, with observed 87% conversion in Grignard reaction as shown above. A complete synthesis route for Com ound (I) starting from compound Compound (XI) is depicted below.

Detailed experimental procedures for the synthesis of benzoate salt and final step are given in

International Patent Application Publication WO 2008/079600 Al .


  1.  “Company Overview of Eli Lilly & Co., Worldwide License to Develop and Commercialize VLY-686”. Bloomberg Business. Retrieved 16 November 2015.
  2.  [1]
  3.  “Vanda Pharmaceuticals Announces Tradipitant Phase II Proof of Concept Study Results for Chronic Pruritus in Atopic Dermatitis”. PR Newswire. Retrieved 16 November 2015.
  4.  Schmidt, B (2006). “Proof of principle studies”. Epilepsy Res. 68 (1): 48–52. doi:10.1016/j.eplepsyres.2005.09.019. PMID 16377153.
  5.  George, DT; Gilman, J; Hersh, J; et al. (2008). “Neurokinin 1 receptor antagonism as a possible therapy for alcoholism.”. Science. 6: 1536–1539. doi:10.2147/SAR.S70350. PMC 4567173Freely accessible. PMID 26379454.
  6.  Tauscher, J; Kielbasa, W; Iyengar, S; et al. (2010). “Development of the 2nd generation neurokinin-1 receptor antagonist LY686017 for social anxiety disorder”. European Neuropsychopharmacology. 20 (2): 80–87. doi:10.1016/j.euroneuro.2009.10.005. PMID 20018493.

George, D.T.; Gilman, J.; Hersh, J.; Thorsell, A.; Herion, D.; Geyer, C.; Peng, X.; Kielbasa, W.; Rawlings, R.; Brandt, J.E.; Gehlert, D.R.; Tauscher, J.T.; Hunt, S.P.; Hommer, D.; Heilig, M. Neurokinin 1 receptor antagonism as a possible therapy for alcoholism, Science 2008, 319(5869): 1536

Gackenheimer, S.L.; Gehlert, D.R.In vitro and in vivo autoradiography of the NK-1 antagonist (3H)-LY686017 in guinea pig brain39th Annu Meet Soc Neurosci (October 17-21, Chicago) 2009, Abst 418.16

Tonnoscj, K.; Zopey, R.; Labus, J.S.; Naliboff, B.D.; Mayer, E.A.
The effect of chronic neurokinin-1 receptor antagonism on sympathetic nervous system activity in irritable bowel syndrome (IBS) Dig Dis Week (DDW) (May 30-June 4, Chicago) 2009, Abst T1261

Kopach, M.E.; Kobierski, M.E.; Coffey, D.S.; et al.  
Process development and pilot-plant synthesis of (2-chlorophenyl)[2-(phenylsulfonyl)pyridin-3-yl]methanone
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Patent ID Patent Title Submitted Date Granted Date
US2012225904 New 7-Phenyl-[1, 2, 4]triazolo[4, 3-a]Pyridin-3(2H)-One Derivatives 2010-11-09 2012-09-06
US7381826 Crystalline forms of {2-[1-(3, 5-bis-trifluoromethyl-benzyl)-5-pyridin-4-yl-1H-[1, 2, 3]triazol-4-yl]-pyridin-3-yl}-(2-chlorophenyl)-methanone 2007-04-05 2008-06-03
US7320994 Triazole derivatives as tachykinin receptor antagonists 2005-10-27 2008-01-22
Legal status
Legal status
  • Investigational
CAS Number
PubChem CID
Chemical and physical data
Formula C28H16ClF6N5O
Molar mass 587.90 g/mol
3D model (Jmol)




Tradipitant is being evaluated in a Phase II study in treatment resistant pruritus in atopic dermatitis.

Tradipitant is an NK-1 receptor antagonist licensed from Eli Lilly in 2012. Tradipitant has demonstrated proof-of-concept in alcohol dependence in a study published by the NIH1. In that study tradipitant was shown to reduce alcohol cravings and voluntary alcohol consumption among patients with alcohol dependence. NK-1R antagonists have been evaluated in a number of indications including chemotherapy-induced nausea and vomiting (CINV), post-operative nausea and vomiting (PONV), alcohol dependence, anxiety, depression, and pruritus.

The NK-1R is expressed throughout different tissues of the body, with major activity found in neuronal tissue. Substance P (SP) and NK-1R interactions in neuronal tissue regulate neurogenic inflammation locally and the pain perception pathway through the central nervous system. Other tissues, including endothelial cells and immune cells, have also exhibited SP and NK-1R activity2. The activation of NK-1R by the natural ligand SP is involved in numerous physiological processes, including the perception of pain, behavioral stressors, cravings, and the processes of nausea and vomiting1,2,3. An inappropriate over-expression of SP either in nervous tissue or peripherally could result in pathological conditions such as substance dependence, anxiety, nausea/vomiting, and pruritus1,2,3,4. An NK-1R antagonist may possess the ability to reduce this over-stimulation of the NK-1R, and as a result address the underlying pathophysiology of the symptoms in these conditions.


  1. George DT, Gilman J, Hersh J, Thorsell A, Herion D, Geyer C, Peng X, Keilbasa W, Rawlings R, Brandt JE, Gehlert DR, Tauscher JT, Hunt SP, Hommer D, Heilig M. Neurokinin 1 receptor antagonism as a possible therapy for alcoholism. Science. 2008; 319(5869):1536-9
  2. Almeida TA, Rojo J, Nieto PM, Pinto FM, Hernandez M, et al. Tachykinins and tachykinin receptors: structure and activity relationships. Current Medicinal Chemistry. 2004;11:2045-2081.
  3. Hargreaves R, Ferreira JC, Hughes D, Brands J, Hale J, Mattson B, Mill S. Development of aprepitant, the first neurokinin-1 receptor antagonist for the prevention of chemotherapy-induced nausea and vomiting. Annals of the New York Academy of Sciences. 2011; 1222:40-48.
  4. Stander S, Weisshaar E, Luger A. Neurophysiological and neurochemical basis of modern pruritus treatment. Experimental Dermatology. 2007;17:161-69.

///////////////////tradipitant, PHASE 2, VLY-686,  LY686017, традипитант , تراديبيتانت , 曲地匹坦 , VANDA, ELI LILLY, Gastroparesis Pruritus

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