This post is updated in sept 2015……..

ISAVUCONAZOLE

CLINICAL TRIALS…LINK

PATENTS

Several azoles are currently used for systemic mycoses. However, none of them fulfills the needs of clinical requirement in full extent, particularly with regard 0 to broad antifungal spectrum including aspergillus fumigatus, less drug-drug interaction, and appropriate plasma half-life for once a day treatment. Other clinical requirements which are not fulfilled by the azoles currently used, are efficacy against major systemic mycoses including disseminated aspergillosis, safety, and oral or parenteral formulations. Particularly, demand of a 5 parenteral administration of the azoles is increasing for the treatment of serious systemic mycoses. Most of the azoles on the market as well as under development are highly lipophilic molecules that make the parenteral formulation difficult.

Isavuconazole [(2R,3R)-3-[4-(4-cyanophenyl)thiazol-2-yl)]-1-(1H-1,2,4-triazol-1-yl)-2-(2,5-difluorophenyl)-butan-2-ol; formula I, R¹ and R³ represent fluorine and R² represents hydrogen] as well as Ravuconazole [(2R,3R)-3-[4-(4-cyanophenyl)thiazol-2-yl)]-1-(1H-1,2,4-triazol-1-yl)-2-(2,4-difluorophenyl)-butan-2-ol; formula I, R¹ and R² represent fluorine and R³ represents hydrogen] are useful antifungal drugs as reported in U.S. Pat. No. 5,648,372 from Feb. 1, 1995 or in U.S. Pat. No. 5,792,781 from Sep. 18, 1996 or in U.S. Pat. No. 6,300,353 from Oct. 9, 2001 (WO99/45008).

Since compounds of general formula I contain two adjacent chiral centers, synthesis of enantiomerically pure compound is complex and until now, all patented syntheses are not efficient enough and do not allow cost effective manufacturing on a technical scale:

Thus, U.S. Pat. Nos. 5,648,372 or 5,792,781 describe enantioselective synthesis of compounds of formula I (specifically Ravuconazole) from chiral 3-hydroxy-2-methyl propionic acid in 12 steps with overall yield lower than 5%. In another approach including 13 steps and low overall yield, (R)-lactic acid was used as the starting material (Chem. Pharm. Bull. 46(4), 623 (1998) and ibid. 46(7), 1125 (1998)).

Because both starting materials contain only one chiral center, in a number of inefficient steps, the second, adjacent chiral center has to be created by a diastereoselective reaction (using either Corey or Sharpless epoxidation method) which is not sufficiently selective leading mostly to a mixture of two diastereomers which have to be separated.

The second approach, based on (R)-methyl lactate, was recently very thoroughly optimized by BMS on a multi kilogram scale but it still does not fulfill requirements for cost effective manufacturing process (Organic Process Research & Development 13, 716 (2009)). The overall yield of this optimized 11 steps process is still only 16% (Scheme 1).

The manufacturing process for Isavuconazole is similar: Since Isavuconazole differentiates from Ravuconazole by only another fluorine substitution on the aromatic ring (2,5- instead of 2,4-difluorophenyl), the identical synthesis has been used (U.S. Pat. No. 6,300,353 from Oct. 9, 2001 and Bioorg. & Med. Chem. Lett. 13, 191 (2003)). Consequently, also this manufacturing process, based on (R)-lactic acid, faces the same problems: to many steps, extremely low overall yield and in addition to U.S. Pat. No. 6,300,353 claims even already known step as novel (claim 36).

Recent attempts to improve this concept as reported in WO 2007/062542 (Dec. 1, 2005), using less expensive, natural configured (S)-lactic acid, also failed: As already reported in U.S. Pat. No. 6,133,485 and in US 2003/0236419, the second chiral center was formed from an optically active allyl alcohol prepared in a few steps from (S)-lactic acid.

This allyl alcohol was subjected to Sharpless diastereoselective epoxidation providing first an opposite configured, epimeric epoxy alcohol which had to be then epimerized in an additional inversion step yielding finally the desired epoxy alcohol as the known precursor for Isavuconazole (U.S. Pat. No. 6,300,353). It is obvious that this process using less expensive (S)-lactic acid makes the entire process with an inversion step even more complex than the original approach.

Elegant and more efficient process has been claimed in US 2004/0176432 from Jun. 26, 2001) in which both chiral centers have been formed simultaneously, diastereo- and enantio-selectively pure in one single reaction step using chiral (R)-2-butynol as a chiral precursor in the presence of Pd(II)-catalyst and diethyl zinc (Scheme 2).

Since water soluble, (R)-2-butynol is expensive, recently identical process has been published, in which instead of (R)-2-butynol less water soluble and therefore, less expensive (R)-4-phenyl-3-butyn-2-ol was used (Synthetic Commun. 39, 1611 (2009)). Nevertheless, as incorrectly stated there, this process does not provide better diastereoselectivity than the original process using (R)-2-butynol: On the contrary disadvantage of this process is a very bad atom economy because huge phenyl group of (R)-4-phenyl-3-butyn-2-ol has to be “disposed” in oxidation step by the conversion of triple bond into carboxylic acid function.

All known processes for enantiomerically pure compounds of formula I have definitely too many operation steps and specifically very low overall yield. The chiral starting materials used, either 3-hydroxy-2-methyl propionic acid or (S)- or (R)-methyl lactate, contain only one chiral center and consequently, in number of steps, the second adjacent chiral center has to be ineffectively generated which makes the entire process long and expensive. The only known process, which generates both chiral centers simultaneously, requires again expensive chiral starting material (R)-2-butynol.

ISAVUCONAZOLE

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US6812238

synthetic scheme A, starting from 4-[(2R)-2-(3,4,5,6-tetrahydro-2H-pyran-2-yloxy)-propionyl]morpholine [which can be prepared by a same procedure as described in Chem. Pharm. Bull. 41, 1035, 1993.]. This synthesis route has been described for example in European Patent Application No. 99101360.8.

(a)

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US8207352

Example 1 (2R,3R)-3-[4-(4-cyanophenyl)thiazol-2-yl]-1-(1H-1,2,4-triazol-1-yl)-2-(2,4-difluorophenyl)-butan-2-ol

To a solution of racemic 3-[4-(4-cyanophenyl)thiazol-2-yl]-1-(1H-1,2,4-triazol-1-yl)-2-(2,4-difluorophenyl)-butan-2-ol (43.7 g) in acetone (800 ml) a solution of (1R)-10-camphorsulfonic acid (23 g) in methanol (300 ml) was added and the mixture was heated under reflux until a clear solution was obtained. The solution was slowly cooled to rt, seeded with crystals of the title enantiomeric salt and let overnight. The solid was collected by filtration, washed with acetone and dried to provide (2R,3R)-3-[4-(4-cyanophenyl)thiazol-2-yl]-1-(1H-1,2,4-triazol-1-yl)-2-(2,4-difluorophenyl)-butan-2-ol (1R)-10-camphorsulfonate as white solid. This crude salt was then taken up in methylenechloride (100 ml) and water (ca. 100 ml) and the mixture was basified with aqueous sodium hydroxide solution. The organic layer was separated and the aqueous phase washed twice with methylenechloride (50 ml) and combined. The organic phases were then washed twice with water (2×50 ml), dried with sodium sulfate, filtrated and the solvent removed under reduced pressure. The crude product was then mixed with isopropanol (ca. 150 ml), heated for 10 min, cooled to 0° C. and stirred for ca. 2 hrs. The product was collected, washed with isopropanol and dried under reduced pressure to provide the enantiomerically pure title compound (17.5 g, 41% yield, 99.1% ee);

m.p. 164-166° C.; [α]=−30° (c=1, methanol, 25° C.);

NMR (CDCl3): 1.23 (3H, d, J=8 Hz), 4.09 (1H, q, J=8 Hz), 4.26 (1H, d, J=14 Hz), 4.92 (1H, d, J=14 Hz), 5.75 (1H, s), 6.75-6.85 (2H, m), 7.45-7.54 (2H, m), 7.62 (1H, s), 7.69 (1H, s), 7.75 (1H, d, J=8 Hz), 7.86 (1H, s), 8.03 (1H, d, J=8 Hz).

The analytical data were identical with published (U.S. Pat. No. 5,648,372 and Chem. Pharm. Bull. 1998, 46, 623-630).

Example 2 (2R,3R)-3-[4-(4-cyanophenyl)thiazol-2-yl]-1-(1H-1,2,4-triazol-1-yl)-2-(2,4-difluorophenyl)-butan-2-ol

Racemic 3-[4-(4-cyanophenyl)thiazol-2-yl]-1-(1H-1,2,4-triazol-1-yl)-2-(2,4-difluorophenyl)-butan-2-ol (44 g) and (1R)-10-camphorsulfonic acid (20 g) were suspended in methanol (ca. 300 ml), the slurry was stirred intensively, warmed up to ca. 70° C. and a small addition of acetic acid was added to obtain a clear solution. After cooling of the solution to rt and then to 0° C., the mixture was seeded with enantiomerically pure salt and stirred for another 2 hrs. The crystalline solid was collected by filtration, washed with cooled methanol and dried under reduced pressure. The crystals were partitioned between methylenechloride (300 ml) and saturated aqueous sodium bicarbonate solution (200 ml). The organic layer was washed twice with water (50 ml), dried with magnesium sulphate, filtrated and evaporated under reduced pressure to give the title compound (16.9 g, 38% yield, 95% ee). The analytical data were identical with published (U.S. Pat. No. 5,648,372 or Chem. Pharm. Bull. 1998, 46, 623).

Example 3 (2R,3R)-3-[4-(4-cyanophenyl)thiazol-2-yl]-1-(1H-1,2,4-triazol-1-yl)-2-(2,5-difluorophenyl)-butan-2-ol

To a solution of racemic 3-[4-(4-cyanophenyl)thiazol-2-yl]-1-(1H-1,2,4-triazol-1-yl)-2-(2,5-difluorophenyl)-butan-2-ol (10 g) in acetone (ca. 200 ml) a solution of (1R)-10-camphorsulfonic acid (3.9 g) in methanol (50 ml) was added and the mixture was heated shortly under reflux until a clear solution was obtained. The solution was then slowly cooled to rt, seeded with crystals of the desired enantiomeric salt and let overnight. The solid precipitate was collected by filtration, washed with acetone and dried to provide (2R,3R)-3-[4-(4-cyanophenyl)thiazol-2-yl]-1-(1H-1,2,4-triazol-1-yl)-2-(2,5-difluorophenyl)-butan-2-ol (1R)-10-camphorsulfonate as white solid. This salt was then taken up in methylenechloride and water and basified with aqueous sodium bicarbonate solution. The organic layer was separated and the aqueous phase washed twice with methylenechloride. The organic phases were combined, dried with sodium sulphate, filtrated and the solvent removed under reduced pressure. The crude product was then dissolved in ethanol, the slurry heated for 20 min, small amount of water was added, the solution slowly cooled to 0° C. and stirred for ca. 2 hrs. The product was collected, washed with cold ethanol and dried under reduced pressure to provide the title enantiomerically pure compound (3.9 g, 39% yield, 96% ee). The analytical date were identical with published in U.S. Pat. No. 6,300,353 B1 and WO 99/45008.

Example 4 (2R,3R)-3-[4-(4-cyanophenyl)thiazol-2-yl]-1-(1H-1,2,4-triazol-1-yl)-2-(2,5-difluorophenyl)-butan-2-ol

To a solution of racemic 3-[4-(4-cyanophenyl)thiazol-2-yl]-1-(1H-1,2,4-triazol-1-yl)-2-(2,5-difluorophenyl)-butan-2-ol (100 g) in acetone (1000 ml) a solution of (1R)-10-camphorsulfonic acid (47 g) in methanol (500 ml) was added at rt, then slurry was heated under stirring to almost reflux for ca. 30 min, then cooled slowly to rt, seeded with the pure enantiomeric salt and stirred over night. The solid was collected by filtration, washed with methanol/acetone mixture, dried under reduced pressure. The residue was taken up with a solvent mixture of methylenechloride/water and after addition of saturated aqueous sodium bicarbonate solution the organic phase was separated and aqueous phase washed twice with methylenechloride. The combined organic phases were filtrated, the solvent removed under reduced pressure. Recrystallization of the crude product from aqueous ethanol provided enantiomerically pure title compound: 39 g (39% yield, 92% ee). The analytical data were identical with published: U.S. Pat. No. 6,300,353 and WO 99/45008.

Example 5 (2R,3R)-3-[4-(4-cyanophenyl)thiazol-2-yl]-1-(1H-1,2,4-triazol-1-yl)-2-(2,5-difluorophenyl)-butan-2-ol

A solution of the racemic 3-[4-(4-cyanophenyl)thiazol-2-yl]-1-(1H-1,2,4-triazol-1-yl)-2-(2,5-difluorophenyl)-butan-2-ol (4.4 g) and (1R)-10-camphorsulfonic acid (2 g) in toluene (40 ml) containing glacial acetic acid (0.6 ml) was warmed up to approximately 70° C., then allowed to cool slowly to 20° C., seeded with the pure enantiomeric salt whereupon the pure enantiomeric salt start to crystallize out. After ca. 2 hrs at this temperature the solid was collected, washed with cold toluene and dried. The crystals were taken with a solvent mixture of methylenechloride/water and after addition of aqueous saturated sodium bicarbonate solution the organic phase was separated and aqueous phase washed twice with methylenechloride. The combined organic phases were filtrated and the solvent removed under reduced pressure. Recrystallization of the crude product from aqueous ethanol provided enantiomerically pure title compound: 2 g (45% yield, 99% ee). The analytical data were identical with published: U.S. Pat. No. 6,300,353 and WO 99/45008.

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WO 1999045008

US6300353

The following synthetic scheme 1 illustrates the manufacture of one of the compounds of formula I′:

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Bioorganic and medicinal chemistry letters, 2003 ,  vol. 13,   2  p. 191 – 196

http://www.sciencedirect.com/science/article/pii/S0960894X02008922

read more at

Boyd, B.; Castaner, J.   BAL-4815/BAL-8557
Drugs Fut 2006, 31(3): 187

Antimicrobial Agents and Chemotherapy, 2008 ,  vol. 52,   4  p. 1396 – 1400

Ohwada, J.; Tsukazaki, M.; Hayase, T.; Oikawa, N.; Isshiki, Y.; Umeda, I.; Yamazaki, T.; Ichihara, S.; Shimma, N.Development of novel water antifungal, RO0098557
21st Med Chem Symp (November 28-30, Kyoto) 2001, Abst 1P-06

Ohwada, J.; Tsukazaki, M.; Hayase, T.; et al.
RO0098557, a novel water soluble azole prodrug for parenteral and oral administration (I). Design, synthesis, physicochemical properties and bioconversion42nd Intersci Conf Antimicrob Agents Chemother (ICAAC) (September 27-30, San Diego) 2002, Abst F-820

Tasaka et al., Chem. Pharm. Bull. 41(6) pp. 1035-1042 (1993).

Clinical trials

There have been three phase III clinical trials of isavuconazole, ACTIVE, VITAL and SECURE. As of June 2015, SECURE and VITAL have been presented in abstract form and results from ACTIVE have not been released.^[9]

The SECURE trial compared voriconazole and isavuconazole in invasive fungal infections due to aspergillus. Isuvaconazole was found to be non-inferior to voriconazole, anothertriazole antifungal, with all cause mortality at 18.6%, compared to 20.2% in the voriconazole group. It additionally demonstrated a similar side effect profile.^[10]

Data from the VITAL study showed that isavuconazole could be used in treatment of invasive mucormycosis, but did not evaluate its clinical efficacy for this indication.^[11]

The ACTIVE trial is a comparison of isuvaconazole and caspofungin for invasive candida infections and results are anticipated in the second half of 2015.^[12][13]

References

Isavuconazole

Systematic (IUPAC) name
4-{2-[(1R,2R)-(2,5-Difluorophenyl)-2-hydroxy-1-methyl-3-(1H-1,2,4-triazol-1-yl)propyl]-1,3-thiazol-4-yl}benzonitrile
Clinical data
Trade names	Cresemba (prodrug form)
AHFS/Drugs.com	entry
Pregnancy category	US: C (Risk not ruled out)
Legal status	US: ℞-only ℞ (Prescription only)
Routes of administration	Oral, intravenous
Identifiers
ATC code	None
PubChem	CID: 6918485
ChemSpider	5293682
UNII	60UTO373KE
ChEBI	CHEBI:85979
ChEMBL	CHEMBL409153
NIAID ChemDB	416566
Chemical data
Formula	C22H17F2N5OS
Molecular mass	437.47 g/mol

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