1.  “Apremilast Palace Program Demonstrates Robust and Consistent Statistically Significant Clinical Benefit Across Three Pivotal Phase III Studies (PALACE-1, 2 & 3) in Psoriatic Arthritis” (Press release). Celgene Corporation. 6 September 2012. Retrieved 2012-09-10.
2.  “US HOT STOCKS: OCZ, VeriFone, Men’s Wearhouse, AK Steel, Celgene”. The Wall Street Journal. 6 September 2012. Retrieved 2012-09-06.
3. Discovery of (S)-N-[2-[1-(3-ethoxy-4-methoxyphenyl)-2-methanesulfonylethyl]-1,3-dioxo-2,3-dihydro-1H-isoindol-4-yl] acetamide (apremilast), a potent and orally active phosphodiesterase 4 and tumor necrosis factor-alpha inhibitor.

   Man HW, Schafer P, Wong LM, Patterson RT, Corral LG, Raymon H, Blease K, Leisten J, Shirley MA, Tang Y, Babusis DM, Chen R, Stirling D, Muller GW.

   J Med Chem. 2009 Mar 26;52(6):1522-4. doi: 10.1021/jm900210d.

4. Therapeutics: Silencing psoriasis.Crow JM.Nature. 2012 Dec 20;492(7429):S58-9. doi: 10.1038/492S58a. No abstract available.
5. NMR…http://file.selleckchem.com/downloads/nmr/S803401-Apremilast-HNMR-Selleck.pdf
6. WO 2003080049
7. WO 2013126495
8. WO 2013126360
9. WO 2003080049
10. WO 2006065814
11. US2003/187052 A1 …..MP 144 DEG CENT
12. US2007/155791
13. J. Med. Chem., 2008, 51 (18), pp 5471–5489
    DOI: 10.1021/jm800582j
14. J. Med. Chem., 2011, 54 (9), pp 3331–3347
    DOI: 10.1021/jm200070e

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INTRODUCTION

2-[l-(3-ethoxy-4-methoxyphenyl)-2-methylsulfonylethyl]-4- acetylaminoisoindoline-l ,3-dione is a PDE4 inhibitor that is currently under investigation as an anti-inflammatory for the treatment of a variety of conditions, including asthma, chronic obstructive pulmonary disease, psoriasis and other allergic, autoimmune and rheumatologic conditions. S-enantiomer form of 2-[l-(3-ethoxy-4-methoxyphenyl)-2-methylsulfonylethyl]-4- acetylaminoisoindoline-l ,3-dione can be prepared by reacting (5)-aminosulfone 1 with intermediate 2.

Existing methods for synthesizing (S)-aminosulfone 1 involve resolution of the corresponding racemic aminosulfone by techniques known in the art. Examples include the formation and crystallization of chiral salts, and the use of chiral high performance liquid chromatography. See, e.g., Jacques, J., et al., Enantiomers, Racemates and Resolutions (Wiley Interscience, New York, 1981); Wilen, S. H., et al, Tetrahedron 33:2725 (1977); Eliel, E. L., Stereochemistry of Carbon Compounds (McGraw Hill, NY, 1962); and Wilen, S. H., Tables of Resolving Agents and Optical Resolutions p. 268 (E.L. Eliel, Ed., Univ. of Notre Dame Press, Notre Dame, IN, 1972). In one example, as depicted in Scheme 1 below, (5)-aminosulfone 1 is prepared by resolution of racemic aminosulfone 3 with N-Ac-L-Leu. Racemic aminosulfone 3 is prepared by converting 3-ethoxy-4-methoxybenzonitrile 4 to enamine intermediate 5 followed by enamine reduction and borate hydrolysis. This process has been reported in U.S. Patent

Application Publication No. 2010/0168475.

CH₂CI₂, NaOH

Scheme 1

The procedure for preparing an enantiomerically enriched or enantiomerically pure aminosulfone, such as compound 1, may be inefficient because it involves the resolution of racemic aminosulfone 3. Thus, a need exists as to asymmetric synthetic processes for the preparation of an enantiomerically enriched or enantiomerically pure aminosulfone, particularly for manufacturing scale production. Direct catalytic asymmetric hydrogenation of a suitable enamine or ketone intermediate is of particular interest because it eliminates the need for either classic resolution or the use of stoichiometric amount of chiral auxiliary, and thus, may be synthetically efficient and economical.

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SYNTHESIS OF KEY INTERMEDIATE

WO2013126495A2

Example 1

Synthesis of 1 -(3-ethoxy-4-methoxyphenyl)-2-(methylsulfonyl)ethenamine

[00232] A slurry of dimethylsulfone (85 g, 903 mmol) in THF (480 ml) was treated with a

1.6M solution of n-butyllithium in hexane (505 ml, 808 mmol) at 0 – 5 °C. The resulting mixture was agitated for 1 hour then a solution of 3-ethoxy-4-methoxybenzonitrile (80 g, 451 mmol) in THF (240 ml) was added at 0 – 5 °C. The mixture was agitated at 0 – 5 °C for 0.5 hour, warmed to 25 – 30 °C over 0.5 hour and then agitated for 1 hour. Water (1.4 L) was added at 25 – 30 °C and the reaction mass was agitated overnight at room temperature (20 – 30 °C). The solid was filtered and subsequently washed with a 2: 1 mixture of water :THF (200 ml), water (200 ml) and heptane (2 x 200 ml). The solid was dried under reduced pressure at 40 – 45 °C to provide the product as a white solid (102 g, 83% yield); 1H NMR (DMSO-d₆) δ 1.34 (t, J=7.0 Hz, 3H), 2.99 (s, 3H), 3.80 (s, 3H), 4.08 (q, J=7.0 Hz, 2H), 5.03 (s, 1H), 6.82 (s, 2H), 7.01 (d, J=8.5 Hz, 1H), 7.09 – 7.22 (m, 2H).

Example 2

Synthesis of (R)- 1 -(3-ethoxy-4-methoxyphenyl)-2-(methylsulfonyl)ethanamine

[00233] A solution of bis(l,5-cyclooctadiene)rhodium(I) trifluoromethanesulfonate (36 mg, 0.074 mmol) and (i?)-l-[(5)-2-(diphenylphosphino)ferrocenyl]ethyldi-tert-butylphosphine (40 mg, 0.074 mmol) in 25 mL of 2,2,2-trifluoroethanol was prepared under nitrogen. To this solution was then charged l-(3-ethoxy-4-methoxyphenyl)-2-(methylsulfonyl)ethenamine (2.0 g, 7.4 mmol). The resulting mixture was heated to 50 °C and hydrogenated under 90 psig hydrogen pressure. After 18 h, the mixture was cooled to ambient temperature and removed from the hydrogenator. The mixture was evaporated and the residue was purified by chromatography on a CI 8 reverse phase column using a water-acetonitrile gradient. The appropriate fractions were pooled and evaporated to -150 mL. To this solution was added brine (20 mL), and the resulting solution was extracted with EtOAc (3 x 50 mL). The combined organic layers were dried (MgS0₄) and evaporated to provide the product as a white crystalline solid (1.4 g, 70% yield); achiral HPLC (Hypersil BDS C₈, 5.0 μπι, 250 x 4.6 mm, 1.5 mL/min, 278nm, 90/10 gradient to 80/20 0.1% aqueous TFA/MeOH over 10 min then gradient to 10/90 0.1% aqueous TFA/MeOH over the next 15 min): 9.11 (99.6%); chiral HPLC (Chiralpak AD-H 5.0 μιη Daicel, 250 x 4.6 mm, 1.0 mL/min, 280 nm, 70:30:0.1 heptane-z-PrOH-diethylamine): 7.32 (97.5%), 8.26 (2.47%); 1H NMR (DMSO-de) δ 1.32 (t, J= 7.0 Hz, 3H), 2.08 (s, 2H), 2.96 (s, 3H), 3.23 (dd, J= 3.6, 14.4 Hz, 1H), 3.41 (dd, J= 9.4, 14.4 Hz, 1H), 3.73 (s, 3H), 4.02 (q, J= 7.0 Hz, 2H), 4.26 (dd, J= 3.7, 9.3 Hz, 1H), 6.89 (s, 2H), 7.02 (s, 1H); ¹³C NMR (DMSO-d₆) δ 14.77, 41.98, 50.89, 55.54, 62.03, 63.68, 111.48, 111.77, 118.36, 137.30, 147.93, 148.09. Example 3

Synthesis of (6 -l-(3-ethoxy-4-methoxyphenyl)-2-(methylsulfonyl)ethanamine N-Ac-L-Leu salt

[00234] A solution of bis(l,5-cyclooctadiene)rhodium(I) trifluoromethanesulfonate (17 mg, 0.037 mmol) and (5)-l-[(i?)-2-(diphenylphosphino)ferrocenyl]ethyldi-tert-butylphosphine (20 mg, 0.037 mmol) in 10 mL of 2,2,2-trifluoroethanol was prepared under nitrogen. To this solution was then charged l-(3-ethoxy-4-methoxyphenyl)-2-(methylsulfonyl)ethenamine (2.0 g, 7.4 mmol). The resulting mixture was heated to 50 °C and hydrogenated under 90 psig hydrogen pressure. After 18 h, the mixture was cooled to ambient temperature and removed from the hydrogenator. Ecosorb C-941 (200 mg) was added and the mixture was stirred at ambient temperature for 3 h. The mixture was filtered through Celite, and the filter was washed with additional trifluoroethanol (2 mL). Then, the mixture was heated to 55 °C, and a solution of N- acetyl-L-leucine (1.3 g, 7.5 mmol) was added dropwise over the course of 1 h. Stirring proceeded at the same temperature for 1 h following completion of the addition, and then the mixture was cooled to 22 °C over 2 h and stirred at this temperature for 16 h. The crystalline product was filtered, rinsed with methanol (2 x 5 mL), and dried under vacuum at 45 °C to provide the product as a white solid (2.6 g, 80% yield); achiral HPLC (Hypersil BDS Cg, 5.0 μιη, 250 x 4.6 mm, 1.5 mL/min, 278nm, 90/10 gradient to 80/20 0.1% aqueous TFA/MeOH over 10 min then gradient to 10/90 0.1% aqueous TFA/MeOH over the next 15 min): 8.57 (99.8%); chiral HPLC (Chiralpak AD-H 5.0 μιη Daicel, 250 x 4.6 mm, 1.0 mL/min, 280 nm, 70:30:0.1 heptane-z-PrOH-diethylamine): 8.35 (99.6%); 1H NMR (DMSO-<¾) δ 0.84 (d, 3H), 0.89 (d, J= 6.6 Hz, 3H), 1.33 (t, J= 7.0 Hz, 3H), 1.41 – 1.52 (m, 2H), 1.62 (dt, J= 6.7, 13.5 Hz, 1H), 1.83 (s, 3H), 2.94 (s, 3H), 3.28 (dd, J= 4.0, 14.4 Hz, 1H), 3.44 (dd, J= 9.1, 14.4 Hz, 1H), 3.73 (s, 3H), 4.02 (q, J= 6.9 Hz, 2H), 4.18 (q, J= 7.7 Hz, 1H), 4.29 (dd, J= 4.0, 9.1 Hz, 1H), 5.46 (br, 3H), 6.90 (s, 2H), 7.04 (s, 1H), 8.04 (d, J= 7.9 Hz, 1H); Anal. (C₂₀H₃₄N₂O₇S) C, H, N. Calcd C, 53.79; H, 7.67; N 6.27. Found C, 53.78; H, 7.57; N 6.18.

SUBSEQUENT CONVERSION

S-enantiomer form of 2-[l-(3-ethoxy-4-methoxyphenyl)-2-methylsulfonylethyl]-4- acetylaminoisoindoline-l ,3-dione can be prepared by reacting (5)-aminosulfone 1 with intermediate 2.

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APREMILAST

GENERAL SYNTHESIS AND SYNTHESIS OF APREMILAST

WO2012083153A1

(apremilast)

[0145] Preparation of 3-Ethoxy-4-methoxybenzonitrile (Compound 2). 3-Ethoxy-

4-methoxybenzaldehyde (Compound 1, 10.0 gm, 54.9 mmol, Aldrich) and hydroxylamine hydrochloride (4.67 gm, 65.9 mmol, Aldrich) were charged to a 250 mL three-necked flask at room temperature, followed by the addition of anhydrous acetonitrile (50 mL). The reaction mixture was stirred at room temperature for thirty minutes and then heated to reflux (oil bath at 85 °C). After two hours of reflux, the reaction mixture was cooled to room temperature, and added 50 mL of deionized water. The mixture was concentrated under reduced pressure to remove acetonitrile and then transferred to a separatory funnel with an additional 80 mL of deionized water and 80 mL dichloromethane. The aqueous layer was extracted with dichloromethane (3 x 50 mL). The combined organic layers were washed successively with water (80 mL) and saturated sodium chloride (80 mL). The organic layer was dried over anhydrous sodium sulfate (approximately 20 gm). The organic layer was filtered and concentrated under reduced pressure to give a yellow oil. Purification by silica gel chromatography (0 to 1 % MeOH/DCM ) afforded 3-Ethoxy-4-methoxybenzonitrile

(Compound 2) as a white solid (7.69 gm, 79 % yield). MS (ESI positive ion) m/z 178.1 (M + 1). HPLC indicated >99% purity by peak area. 1H-NMR (500 MHz, DMSO-c¾: δ ppm 1.32 (t, 3H), 3.83 (s, 3H), 4.05 (q, 2H), 7.10 (d, J = 8.0 Hz, 1H), 7.35 (d, J = 2.0 Hz, 1H), 7.40 (dd, J = 2.0 Hz, 1H).

[0146] Preparation of l-(3-Ethoxy-4-methoxyphenyi)-2-

(niethylsulfonyl)ethanamine (Compound 3). Dimethyl sulfone (2.60 gm, 27.1 mmol, Aldrich) and tetrahydrofuran (10 mL, Aldrich) were charged to a 250 mL three-necked flask at room temperature. The mixture was cooled to 0 – 5 °C, and the solution gradually turned white. n-Butyllithium (10.8 mL, 27.1 mmol, 2.5 M solution in hexanes, Aldrich) was added to the flask at a rate such that the reaction mixture was maintained at 5 – 10 °C. The mixture was stirred at 0 – 5 °C for one hour, turning light-yellow. 3-Ethoxy-4-methoxybenzonitrile (Compound 2, 4.01 gm, 22.5 mmol) in tetrahydrofuran (8 mL) was then charged to the flask at a rate such that the reaction mixture was maintained at 0 – 5 °C. The mixture was stirred at 0 – 5 °C for another 15 minutes. After warming to room temperature, the reaction mixture was stirred for another 1.5 hours and then transferred to a second 250 mL three-necked flask containing a suspension of sodium borohydride (1.13 gm, 29.3 mmol, Aldrich) in

tetrahydrofuran (1 1 mL), maintained at – 5 – 0 °C for 30 minutes. Trifluoroacetic acid (“TFA,” 5.26 mL, 68.3 mmol, Aldrich) was charged to the flask at a rate such that the reaction mixture was maintained at 0 – 5 °C. The mixture was stirred at 0 – 5 °C for 40 minutes and an additional 17 hours at room temperature. The reaction mixture was then charged with 2.7 mL of deionized water over five minutes at room temperature. The mxiture was stirred at room temperature for 15 hours. Aqueous NaOH (10 N, 4.9 mL) was charged to the flask over 15 minutes at 45 °C. The mixture was stirred at 45 °C for two hours, at 60 °C for 1.5 hours, and at room temperature overnight. After approximately 17 hours at room temperature the mixture was cooled to 0 °C for thirty minutes and then concentrated under reduced pressure. The residual material was charged with deionized water (3 mL) and absolute ethanol (3 mL) and stirred at 0 – 5 °C for 2 hours. The mixture was filtered under vacuum, and the filtered solid was washed with cold absolute ethanol (3 x 5 mL), followed by deionized water until the pH of the wash was about 8. The solid was air dried overnight, and then in a vacuum oven at 60 °C for 17 hours to afford Compound 3 as a white solid (4.75 gm, 77 %). MS (ESI positive ion) m/z 274.1 (M + 1). Ή-NMR (500 MHz, DMSO-c¾): δ ppm 1.32 (t, J = 7.0 Hz, 3H), 2.08 (bs, 2H), 2.95 (s, 3H), 3.23 (dd, J = 4.0 Hz, 1H), 3.40 (dd, J = 9.5 Hz, 1H), 3.72 (s, 3H), 4.01 (q, J = 7.0 Hz, 2H), 4.25 (dd, J = 3.5 Hz, 1H), 6.88 (s, 2H), 7.02 (s, 1H).

[0147] Preparation of 4-Nitroisobenzofuran-l,3-dione (Compound 5). Into a 250 mL round bottom flask, fitted with a reflux condenser, was placed 3-nitrophthalic acid (21.0 gm, 99 mmol, Aldrich) and acetic anhydride (18.8 mL, 199 mmol, Aldrich). The solid mixture was heated to 85 °C, under nitrogen, with gradual melting of the solids. The yellow mixture was heated at 85 °C for 15 minutes, and there was noticeable thickening of the mixture. After 15 minutes at 85 °C, the hot mixture was poured into a weighing dish, and allowed to cool. The yellow solid was grinded to a powder and then placed on a cintered funnel, under vacuum. The solid was washed with diethyl ether (3 x 15 mL), under vacuum and allowed to air dry overnight, to afford 4-nitroisobenzofuran-l ,3-dione, Compound 5, as a light-yellow solid (15.8 gm, 82 %). MS (ESI positive ion) m/z 194.0 (M + 1). TLC: Rf = 0.37 (10% MeOH/DCM with 2 drops Acetic acid) Ή-NMR (500 MHz, DMSO-i¾: δ ppm 8.21 (dd, J = 7.5 Hz, 1H), 8.39 (dd, J = 7.5 Hz, 1H), 8.50 (dd, J = 7.5 Hz, 1 H).

[0148] Preparation of 2-(l-(3-Ethoxy-4-methoxyphenyI)-2-

(methylsulfonyl)ethyl)-4-nitroisoindoline-l,3-dione (Compound 6). Into a 2 – 5 mL microwave vial was added 4-nitroisobenzofuran-l ,3-dione (Compound 5, 0.35 gm, 1.82 mmol), the amino-sulfone intermediate (Compound 3, 0.50 gm, 1.82 mmol) and 4.0 mL of glacial acetic acid. The mixture was placed in a microwave at 125 °C for 30 minutes. After 30 minutes the acetic acid was removed under reduced pressure. The yellow oil was taken up in ethyl acetate and applied to a 10 gm snap Biotage samplet. Purification by silica gel chromatography (0 to 20 % Ethyl Acetate/Hexanes) afforded Compound 6 as a light-yellow solid (0.67 gm, 82 %). MS (ESI positive ion) m/z 449.0 (M + 1). TLC: Rf = 0.19

(EtOAc:Hexanes, 1 : 1). HPLC indicated 99% purity by peak area. Ή-NMR (500 MHz, DMSO-c¾: δ ppm 1.32 (t, 3H), 2.99 (s, 3H), 3.73 (s, 3H), 4.02 (m, 2H), 4.21 (dd, J = 5.0 Hz, 1H), 4.29 (dd, J = 10.0 Hz, 1H), 5.81 (dd, J = 5.0 Hz, 1H), 6.93 (d, J – 8.5 Hz, 1H), 7.00 (dd, J = 2.0 Hz, 1H), 7.10 (d, J = 2.5 Hz, 1H), 8.07 (t, J = 15.5 Hz, 1H), 8.19 (dd, J = 8.5 Hz, 1H), 8.30 (dd, J = 9.0 Hz, 1H).

[0149] Preparation of 4-Amino-2-(l-(3-ethoxy-4-methoxyphenyl)-2-

(methylsulfonyl)ethyl)isoindoline-l,3-dione (Compound 7). Compound 6 (0.54 gm, 1.20 mmol) was taken up in ethyl acetate / acetone (1 : 1 , 24 mL) and flowed through the H-cube™ hydrogen reactor using a 10 % Pd/C CatCart™ catalyst cartridge system (ThalesNano, Budapest Hungary). After eluting, the yellow solvent was concentrated under reduced pressure to give Compound 7 as a yellow foam solid (0.48 gm, 95 %). MS (ESI positive ion) m/z 419.1 (M + 1). 1H-NMR (500 MHz, DMSO-<¾): δ ppm 1.31 (t, J = 7.0 Hz, 3H), 2.99 (s, 3H), 3.72 (s, 3H), 4.04 (q, J = 7.0 Hz, 2H), 4.09 (m, 1H), 4.34 (m, 1H), 5.71 (dd, J = 5.5 Hz, 1H), 6.52 (bs, 2H), 6.92-6.98 (m, 3H), 7.06 (bs, 1 H), 7.42 (dd, J = 7.0 Hz, 1H).

[0150] Preparation of N-(2-(l-(3-ethoxy-4-methoxyphenyl)-2-

(methylsuIfonyl)ethyl)-l,3-dioxoisoindolin-4-yl)acetamide (Apremilast, Compound 8).

Into a 2-5 mL microwave vial was placed Compound 7 (0.18 gm, 0.43 mmol), acetic anhydride (0.052 mL, 0.53 mmol) and acetic acid (4 mL). The microwave vial was placed into a Biotage microwave and heated to 125 ^°C for 30 minutes. The solvents were removed under reduced pressure and the residue was purified by silica gel chromatography (0 to 5% MeOH/DCM) to afford apremilast (Compound 8) as a yellow oil (0.14 gm, 71%). HPLC indicated 94.6% purity by peak area.

1H-NMR (500 MHz, DMSO-c ₆): δ ppm 1.31 (t, 3H), 2.18 (s, 3H), 3.01 (s, 3H), 3.73 (s, 3H), 4.01 (t, J = 7.0 Hz, 2H), 4,14 (dd, J = 4.0 Hz, 1H), 4.33 (m, 1H), 5.76 (dd, J = 3.0 Hz, 1H), 6.95 (m, 2H), 7.06 (d, J = 1.5 Hz, 1H), 7.56 (d, J = 7.0 Hz, 1H), 7.79 (t, J = 7.7 Hz, 1H), 8.43 (d, J = 8.5 Hz, 1H), 9.72 (bs, 1H).

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SYNTHESIS

EP2501382A1

5. EXAMPLES

Certain embodiments provided herein are illustrated by the following non-limiting examples.

5.1 PREPARATION OF (+)-2-[l-(3-ETHOXY-4-METHOXYPHENYL)-2- METHANESULFONYLETHYLJ-4- ACETYL AMINOISOINDOLIN-1,3- DIONE (APREMILAST)

5.1.1 Preparation of 3-aminopthalic acid

10% Pd/C (2.5 g), 3-nitrophthalic acid (75.0 g, 355 mmol) and ethanol (1.5 L) were charged to a 2.5 L Parr hydrogenator under a nitrogen atmosphere. Hydrogen was charged to the reaction vessel for up to 55 psi. The mixture was shaken for 13 hours, maintaining hydrogen pressure between 50 and 55 psi. Hydrogen was released and the mixture was purged with nitrogen 3 times. The suspension was filtered through a celite bed and rinsed with methanol. The filtrate was concentrated in vacuo. The resulting solid was reslurried in ether and isolated by vacuum filtration. The solid was dried in vacua to a constant weight, affording 54 g (84%> yield) of 3-aminopthalic acid as a yellow product. 1H-NMR (DMSO-d₆) δ: 3.17 (s, 2H), 6.67 (d, 1H), 6.82 (d, 1H), 7.17 (t, 1H), 8-10 (brs, 2H). ¹³C-NMR(DMSO-d₆) δ: 112.00, 115.32, 118.20, 131.28, 135.86, 148.82, 169.15, 170.09.

5.1.2 Preparation of 3-acetamidopthalic anhydride

A I L 3 -necked round bottom flask was equipped with a mechanical stirrer, thermometer, and condenser and charged with 3-aminophthalic acid (108 g, 596 mmol) and acetic anhydride (550 mL). The reaction mixture was heated to reflux for 3 hours and cooled to ambient temperature and further to 0-5. degree. C. for another 1 hour. The crystalline solid was collected by vacuum filtration and washed with ether. The solid product was dried in vacua at ambient temperature to a constant weight, giving 75 g (61% yield) of 3-acetamidopthalic anhydride as a white product. 1H-NMR (CDCI₃) δ: 2.21 (s, 3H), 7.76 (d, 1H), 7.94 (t, 1H), 8.42 (d, 1H), 9.84 (s, 1H).

5.1.3 Resolution of 2-(3-ethoxy-4-methoxyphenyl)-l-(methylsulphonyl)- ethyl-2-amine

A 3 L 3 -necked round bottom flask was equipped with a mechanical stirrer, thermometer, and condenser and charged with 2-(3-ethoxy-4-methoxyphenyl)-l-(methylsulphonyl)-eth-2-ylamine (137.0 g, 500 mmol), N-acetyl-L-leucine (52 g, 300 mmol), and methanol (1.0 L). The stirred slurry was heated to reflux for 1 hour. The stirred mixture was allowed to cool to ambient temperature and stirring was continued for another 3 hours at ambient temperature. The slurry was filtered and washed with methanol (250 mL). The solid was air-dried and then dried in vacuo at ambient temperature to a constant weight, giving 109.5 g (98% yield) of the crude product (85.8% ee). The crude solid (55.0 g) and methanol (440 mL) were brought to reflux for 1 hour, cooled to room temperature and stirred for an additional 3 hours at ambient temperature. The slurry was filtered and the filter cake was washed with methanol (200 mL). The solid was air-dried and then dried in vacuo at 30°C. to a constant weight, yielding 49.6 g (90%> recovery) of (S)-2-(3-ethoxy-4- methoxyphenyl)-l-(methylsulphonyl)-eth-2-ylamine-N-acety 1-L-leucine salt (98.4% ee). Chiral HPLC (1/99 EtOH/20 mM KH₂P0₄ @pH 7.0, Ultron Chiral ES-OVS from Agilent Technologies, 150 mm.times.4.6 mm, 0.5 mL/min., @240 nm): 18.4 min (S-isomer, 99.2%), 25.5 min (R-isomer, 0.8%)

5.1.4 Preparation of (+)-2-[l-(3-ethoxy-4-methoxyphenyl)-2- methanesulfonylethyl] -4-acetylaminoisoindolin- 1 ,3-dione

A 500 mL 3 -necked round bottom flask was equipped with a mechanical stirrer,

thermometer, and condenser. The reaction vessel was charged with (S)-2-(3-ethoxy-4- methoxyphenyl)-l-(methylsulphonyl)-eth-2-yl amine N-acetyl-L-leucine salt (25 g, 56 mmol, 98% ee), 3-acetamidophthalic anhydride (12.1 g, 58.8 mmol), and glacial acetic acid (250 mL). The mixture was refluxed over night and then cooled to <50°C. The solvent was removed in vacuo, and the residue was dissolved in ethyl acetate. The resulting solution was washed with water (250 mL x

2), saturated aqeous NaHC0₃ (250 mL.times.2), brine (250 mL.times.2), and dried over sodium sulphate. The solvent was evaporated in vacuo, and the residue recrystallized from a binary solvent containing ethanol (150 mL) and acetone (75 mL). The solid was isolated by vacuum filtration and washed with ethanol (100 mL.times.2). The product was dried in vacuo at 60°C. to a constant weight, affording 19.4 g (75% yield) of Compound 3 APREMILAST with 98% ee. Chiral HPLC (15/85 EtOH/20 mM KH₂P0₄ @pH 3.5, Ultron Chiral ES-OVS from Agilent Technology, 150 mm x 4.6 mm, 0.4 mL/min., @240 nm): 25.4 min (S-isomer, 98.7%), 29.5 min (R-isomer, 1.2%).

1H-NMR (CDC1₃) δ: 1.47 (t, 3H), 2.26 (s, 3H), 2.87 (s, 3H), 3.68-3.75 (dd, 1H), 3.85 (s, 3H), 4.07-4.15 (q, 2H), 4.51-4.61 (dd, 1H), 5.84-5.90 (dd, 1H), 6.82-8.77 (m, 6H), 9.46 (s, 1H).

¹³C-NMR(DMSO-d₆) δ: 14.66, 24.92, 41.61, 48.53, 54.46, 55.91, 64.51, 111.44, 112.40, 115.10, 118.20, 120.28, 124.94, 129.22, 131.02, 136.09, 137.60, 148.62, 149.74, 167.46, 169.14, 169.48.

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NMR

US20100129363

¹H-NMR (CDCl₃) δ: 1.47 (t, 3H), 2.26 (s, 3H), 2.87 (s, 3H), 3.68-3.75 (dd, 1H), 3.85 (s, 3H), 4.07-4.15 (q, 2H), 4.51-4.61 (dd, 1H), 5.84-5.90 (dd, 1H), 6.82-8.77 (m, 6H), 9.46 (s, 1H). ¹³C-NMR (DMSO-d₆) δ: 14.66, 24.92, 41.61, 48.53, 54.46, 55.91, 64.51, 111.44, 112.40, 115.10, 118.20, 120.28, 124.94, 129.22, 131.02, 136.09, 137.60, 148.62, 149.74, 167.46, 169.14, 169.48.

…………….

APREMILAST

^aReagents and conditions: (a) LiN(SiMe₃)₂, then Me₂SO₂/n-BuLi/BF₃Et₂O, −78 °C; (b) N-Ac-l-leucine, MeOH; (c) HOAc, reflux.

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SARCOIDOSIS

Sarcoidosis is a disease of unknown cause. Sarcoidosis is characterized by the presence of granulomas in one or more organ systems. The most common sites of involvement are the lungs and the lymph nodes in the mediastinum and hilar regions. However, sarcoidosis is a systemic disease and a variety of organ systems or tissues may be the source of primary or concomitant clinical manifestations and morbidity. The clinical course of sarcoidosis is extremely variable, and ranges from a mild or even asymptomatic disease with spontaneous resolution to a chronic progressive disease leading to organ system failure and, in 1-5% of cases, death. See Cecil

Textbook of Medicine, 21st ed. (Goldman, L., Bennett, J. C. eds), W. B. Saunders Company, Philadelphia, 2000, p. 433-436.

While the cause of sarcoidosis is unknown, a substantial body of information suggests that immune mechanisms are important in disease pathogenesis. For example, sarcoidosis is

characterized by enhanced lymphocyte and macrophage activity. See Thomas, P.D. and

Hunninghake, G.W., Am. Rev. Respir. Dis., 1987, 135: 747-760. As sarcoidosis progresses, skin rashes, erythema nodosum and granulomas may form. Granulomas or fibrosis caused by sarcoidosis can occur throughout the body, and may affect the function of vital organs such as the lungs, heart, nervous system, liver or kidneys. In these cases, the sarcoidosis can be fatal. See

http://www.nlm.nih.gov/medlineplus/sarcoidosis.html (accessed November 12, 2009).

Moreover, a variety of exogenous agents, both infectious and non-infectious, have been hypothesized as a possible cause of sarcoidosis. See Vokurka et ah, Am. J. Respir. Crit. Care Med., 1997, 156: 1000-1003; Popper et al, Hum. Pathol, 1997, 28: 796-800; Almenoff et al, Thorax, 1996, 51 : 530-533; Baughman et al., Lancet, 2003, 361 : 1111-1118. These agents include mycobaceria, fungi, spirochetes, and the agent associated with Whipple’s disease. Id.

Sarcoidosis may be acute or chronic. Specific types of sarcoidosis include, but are not limited to, cardiac sarcoidosis, cutaneous sarcoidosis, hepatic sarcoidosis, oral sarcoidosis, pulmonary sarcoidosis, neurosarcoidosis, sinonasal sarcoidosis, Lofgren’s syndrome, lupus pernio, uveitis or chronic cutaneous sarcoidosis.

As the lung is constantly confronted with airborne substances, including pathogens, many researchers have directed their attention to identification of potential causative transmissible agents and their contribution to the mechanism of pulmonary granuloma formation associated with sarcoidosis. See Conron, M. and Du Bois, R.M., Clin. Exp. Allergy, 2001, 31 : 543-554; Agostini et al, Curr. Opin. Pulm. Med. , 2002, 8: 435-440.

Corticosteroid drugs are the primary treatment for the inflammation and granuloma formation associated with sarcoidosis. Rizatto et al. , Respiratory Medicine, 1997, 91 : 449-460. Prednisone is most often prescribed drug for the treatment of sarcoidosis. Additional drugs used to treat sarcoidosis include methotrexate, azathioprine, hydroxychloroquine, cyclophosphamide, minocycline, doxycycline and chloroquin. TNF-a blockers such as thalidomide and infliximab have been reported to be effective in treating patients with sarcoidosis. Baughman et al, Chest, 2002, 122: 227-232; Doty et al, Chest, 2005, 127: 1064-1071. Antibiotics have also been studied for the treatment of sarcoidosis, such as penicillin antibiotics, cephalosporin antibiotics, macrolide antibiotics, lincomycin antibiotics, and tetracycline antibiotics. Specific examples include minocycline hydrochloride, clindamycin, ampicillin, or clarithromycin. See, e.g., U.S. Patent Publication No. 2007/0111956.

There currently lacks a Food and Drug Administration-approved therapeutic agent for the treatment of sarcoidosis, and many patients are unable to tolerate the side effects of the standard corticosteroid therapy. See Doty et al, Chest, 2005, 127: 1064-1071. Furthermore, many cases of sarcoidosis are refractory to standard therapy. Id. Therefore, a demand exists for new methods and compositions that can be used to treat patients with sarcoidosis.

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