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Chemical Synthesis of Tofacitinib Citrate
2015-05-10 07:03:46

Pfizer Inc’s oral JAK inhibitor tofacitinib was approved on November 6, 2012 by US FDA for the treatment of rheumatoid arthritis.

辉瑞公司开发的Xeljanz((tofacitinib, 托法替尼)是FDA批准用于治疗类风湿关节炎的首个JAK抑制剂,也是10年来被批准用于治疗类风湿关节炎的第一个口服改善病情抗风湿药(DMARDs)。

Tofacitinib citrate (Xeljanz)
Chemical Name: 3-{(3R,4R)-4-methyl-3-[methyl-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-amino]-piperidin-1-yl}-3-oxo-propionitrile citrate salt
CAS number: 540737-29-9

Synthetic Scheme of Tofacitinib Citrate (Xeljanz, CP-690550-10)

Synthesis conditions for Tofacitinib Citrate (Xeljanz, CP-690550-10)

a)potassium tert-butoxide, Dimethyl carbonate, 2-methyltetrahydrofuran; toluene, 87% yield
b)5% Rh/C (Johnson-Matthey type C101023-5), acetic acid, hydrogen, 72-78°C, 70-80 psi, 75% yield (92.7% cis by GC)
c)benzaldehyde, sodium triacetoxyborohydride, toluene, 73% yield (96.6% cis and 2.5% trans by GC)
d)lithium aluminum hydride, tetrahydrofuran
e)concentrated hydrochloric acid, isopropanol, 87% yield (99.3% cis and 0.7% trans by GC)
f)di-p-toluoyl-L-tartaric acid, sodium hydroxide, water, methanol,42% yield (98.6% enantiomeric excess, 0.6% trans isomer by GC)
g)2,4-dichloro-7H-pyrrolo[2,3-d]pyrimidine, potassium carbonate,water, 95-105° C, 100% yield
h)20 weight% palladium hydroxide on carbon (50% water wet), water, hydrogen,70-75°C, 50 psi
i)ethyl cyanoacetate, 1-butanol,1,8-diazabicyclo[5.4.0]-undec-7-ene(DBU),40 °C, 20 h
j)citric acid monohydrate, water, 1-butanol, 81 °C, 93% yield

References:

Procedures (a) to (e) 

Weiling Cai, James L. Colony,Heather Frost, James P. Hudspeth, Peter M. Kendall, Ashwin M. Krishnan,Teresa Makowski, Duane J. Mazur, James Phillips, David H. Brown Ripin, Sally Gut Ruggeri, Jay F. Stearns, and Timothy D. White; Investigation of Practical Routes for the Kilogram-Scale Production of cis-3-Methylamino-4-methylpiperidinesOrganic Process Research & Development 2005, 9, 51−56

Ripin, D. H.B.; 3-amino-piperidine derivatives and methods of manufacture, US patent application publication, US 2004/0102627 A1

Procedures  (f) to (h)

Ruggeri, Sally, Gut;Hawkins, Joel, Michael; Makowski, Teresa, Margaret; Rutherford, Jennifer, Lea; Urban,Frank,John;Pyrrolo[2,3-d]pyrimidine derivatives: their intermediates and synthesis, PCT pub. No. WO 2007/012953 A 2, US20120259115 A1, United States Patent US8232393. Patent Issue Date: July 31, 2012

Procedures (i) to (j)

Kristin E. Price, Claude Larrive´e-Aboussafy, Brett M. Lillie, Robert W. McLaughlin, Jason Mustakis, Kevin W. Hettenbach, Joel M. Hawkins, and Rajappa Vaidyanathan; Mild and Efficient DBU-Catalyzed Amidation of Cyanoacetates, Organic Letters, 2009, vol.11, No.9, 2003-2006

Detailed production procedures for the synthesis of Tofacitinib Citrate (Xeljanz, CP-690550-10) 

Preparation of 4-methyl-pyridin-3-yl)-carbamic acid methyl ester  (3-Methoxycarbonylamino-4-methylpyridine)  

To a clean, dry, nitrogen-purged 800 L reactor were charged 3-amino-4-methylpyridine (49.9 kg, 461 mol) and 2-methyltetrahydrofuran (383 L). The reaction was heated to 32- 38 °C for at least 90 min. To a clean, dry, nitrogen-purged 2000 L reactor were charged potassium tert-butoxide (104.0 kg, 927 mol) and 2-methyltetrahydrofuran (255 L). The reaction was stirred at 23-27 °C for at least 30 min to break up the potassium tert-butoxide. Dimethyl carbonate (49.9 kg, 554 mol) was added to the slurry of potassium tert-butoxide at a rate that maintained the temperature below 35 °C. The 3-amino-4-methylpyridine solution was added to the 2000 L reactor at a rate that maintained the temperature from 20 to 35 °C. An additional 115 L of 2-methyltetrahydrofuran was added to aid stirring. The mixture was stirred between 20 and 35 °C for at least 2 h. The reaction was sampled and checked for completion by GC, then cooled to 15-20 °C. Water (255 L) was added at a rate to maintain the temper-ature below 25 °C. The mixture was stirred for at least 30 min then allowed to settle for at least 60 min. The phases were separated, and 2-methyltetrahydrofuran (255 L) was added to the aqueous layer. The reaction mixture was allowed to stir for at least 60 min and then allowed to settle for at least 60 min. The phases were separated, and the 2-meth-yltetrahydrofuran layers were combined. Darco KBB (10.0 kg) was added to the organic layer and allowed to stir for at least 30 min. The Darco slurry was filtered through a bed of Celite, and the cake was washed with 2-methyltetrahydro-furan (51 L). The 2-methyltetrahydrofuran was displaced with toluene under vacuum to a final volume of 480-540 L, then the mixture was cooled to 23-27 °C over at least 90 min. After sampling to ensure that the water content was <1%, the slurry was stirred for at least 12 h. The resulting solids were filtered and washed with toluene (212 L). After drying under vacuum at 40-50 °C for at least 12 h with a slight nitrogen bleed, 66.5 kg (400 mol) of (4-methyl-pyridin- 3-yl)carbamic acid methyl ester was isolated in 86.7% yield (99.89% purity by HPLC) mp: 115.3-116.6 °C. 1H NMR (400 MHz, DMSO): ä 9.12 (bs, 1H), 8.46 (s, 1H), 8.18 (d, J ) 4.9 Hz, 1H), 7.20 (d, J ) 4.9 Hz, 1H), 3.64 (s, 3H), 2.19 (s, 3H). 13C NMR (DMSO): 155.6, 146.5, 146.3, 141.4, 134.2, 125.9, 52.6, 17.8. Anal. Calcd for C8H10N2O2:C, 57.82; H, 6.07; N, 16.86. Found: C, 57.71; H, 5.80; N, 16.85.

Preparation of cis-3-Methoxycarbonylamino-4-methylpiperidine 

To a clean, nitrogen-purged 1200 L reactor were charged Darco KBB14 (6.6 kg), (4-methyl-pyridin-3-yl)carbamic acid methyl ester (66.5 kg) and acetic acid (677 L). The mixture was stirred for at least 30 min at 20-30 °C and filtered through a bed of Celite, and the cake was washed with acetic acid (135 L). To a clean, nitrogen-purged 2000 L hydrogena-tion reactor were charged 5% Rh/C (Johnson-Matthey type C101023-5, 16.5 kg) and the (4-methyl-pyridin-3-yl)carbamic acid methyl ester acetic acid solution. The reaction was stirred for at least 15 min and then purged sequentially with nitrogen and hydrogen. The reaction was heated to 72-78 °C and then pressurized with hydrogen gas at 70-80 psig. The reaction was allowed to stir under these conditions until hydrogen uptake ceased. A sample was obtained for reaction completion check by GC. The reaction was purged with nitrogen, and the catalyst was filtered on a water-wet Celite-coated filter. The cake was washed with toluene (212 gal), and the filtrates were combined. The solution of (4-methyl-pipridin-3-yl)carbamic acid methyl ester (92.7% cis by GC) was used in the next step without further purification. In the lab, an aliquot (0.50 g) of the reduced product was purified via silica gel chromatography (20% EtOAc-hexanes) to yield purified product (0.38 g). The purified product was dissolved in IPE (10 mL) and treated with bubbling HCl gas. The white solid was filtered and dried under vacuum to yield a white solid (11.9 g, 75%) mp 199-200.5 °C. Rf freebase) ) 0.21 (5:1 CH2Cl2-CH3OH). Anal. Calcd for C8H17ClN2O2: C,46.04; H, 8.21; N, 13.42. Found: C, 46.93; H, 8.84; N, 12.29. 1H NMR (HCl salt) (400 MHz, CD3OD): ä 6.94 (bs, 1H), 3.95 (m, 1H), 3.66 (m, 4H), 3.38 (dd, J ) 13.27, 4.15, 1H), 3.28 (m, 1H), 3.14 (dd, J ) 13.27, 3.11, 1H), 3.05 (ddd, J ) 12.85, 9.95, 4.56 1H), 2.07 (m, 1H), 1.74 (m, 2H), 1.01 (d, J ) 7.05, 3H). 13C NMR (300 MHz, CD3OD): ä 158.0, 51.6, 48.7, 46.7, 42.9, 31.1, 25.6, 15.1.

Preparation of  cis-N-Benzyl-3-methoxycarbonylamino-4-methylpipe-ridine Hydrochloride

To a clean, nitrogen-purged 2000 L reactor was charged (4-methyl-piperidin-3-yl)carbamic acid methyl ester as the crude acetic acid and toluene solution from the previous step. The acetic acid was displaced with toluene under vacuum to a final volume of 500-560 L. The reaction was cooled and a sample pulled to check for an acetic acid content of <4% as determined by 1H NMR. Benzaldehyde (46.4 kg, 437 mol) was added to the reaction at 20-30 °C and stirred for at least 30 min. To a clean, dry, nitrogen-purged reactor were charged sodium triacetoxy-borohydride (92.6 kg, 437 mol) and toluene (472 L). The mixture was allowed to stir for at least 60 min at 20-30 °C. The benzaldehyde solution was transferred to the sodium triacetoxyborohydride reactor at a rate that maintained the temperature from 20 to 30 °C, then the reaction was stirred for at least 2 h. The reaction was sampled and checked for completion by GC. It was quenched by addition of a solution of 50% aqueous sodium hydroxide (158.9 kg diluted with 352 gal of water), maintaining the temperature at 20-30 °C, until a pH between 6 and 7 was achieved. The reaction was then stirred for at least 60 min and allowed to settle for at least 60 min, and the phases were separated. The toluene layer was heated to 70-80 °C, and concentrated HCl (47.0 kg, 477 mol) was added over at least 30 min. The reaction was held from 70 to 80 °C for at least 60 min. The reaction was cooled to 15-25 °C over at least 60 min and held for at least 2 h. The resulting solids were filtered, and the cake was washed with toluene (190 L). After drying under vacuum at 40-50 °C for at least 12 h with a slight nitrogen bleed, cis-N-benzyl-3-methoxycarbonylamino-4-methylpiperidine hy-drochloride (86.8 kg, 290 mol) was isolated in 73.1% yield over two steps (96.6% cis and 2.5% trans by GC) mp: 187.3-191.4 °C. 1H NMR (400 MHz, CDCl3): ä 12.11 (bs, 1H), 7.57-7.52 (m, 3H), 7.43-7.39 (m, 3H), 4.26 (dd, J ) 13.3, 4.6 Hz, 1H), 4.16 (bd, J ) 9.9 Hz, 1H), 4.07 (dd, J ) 13.3, 5.8 Hz, 1H), 3.60 (s, 3H), 3.49 (bd, J ) 12.0 Hz, 1H), 3.29 (dd, J ) 12.9, 2.1 Hz, 1H), 2.89 (ddd, J ) 12.9, 10.8, 3.3 Hz, 1H), 2.74 (dddd, J ) 12.4, 12.0, 9.5, 2.9 Hz, 1H), 2.22 (dddd, J ) 13.3, 13.0, 12.4, 3.9 Hz, 1H), 1.82-1.74 (m, 1H), 1.64 (bd, J ) 13.0 Hz, 1H), 0.94 (d, J ) 6.6 Hz, 3H). 13C NMR (CDCl3): 157.8, 131.8, 130.5, 129.6, 127.9, 61.3, 56.8, 53.1, 52.5, 48.6, 32.6, 26.2, 17.2. Anal. Calcd for C15H23ClN2O2: C, 60.29; H, 7.76; N, 9.38. Found: C, 60.21; H, 7.83; N, 9.29.

Preparation of cis-N-Benzyl-3-methylamino-4-methypiperidine Bis-(hydrochloride)

To a clean, dry, nitrogen-purged 2000 L reactor were charged (1-benzyl-4-methyl-piperidin-3-yl)-carbamic acid methyl ester hydrochloride (41.9 kg, 140 mol) and tetrahydrofuran (685 L). The reactor was purged three times with nitrogen and allowed to stir for at least 45 min at 20-30 °C to break up the solids. A sample was pulled to ensure that the water content was <0.2% water. The reaction was cooled to between -15 to 5 °C, and a 1.0 M solution of lithium aluminum hydride in tetrahydrofuran (181.4 kg, 200 mol) was added at a rate to maintain the temperature from -15 to 5 °C. The charge line was rinsed with tetrahydrofuran (19 gal), and the reaction was heated and held at reflux for at least 2.5 h. After cooling to 20-30 °C, the reaction was sampled and checked for completion by GC. The reaction was cooled to between -10 and 5 °C and a chilled (-10 to 5 °C) solution of tetrahydrofuran (43 L) and water (16.3 kg) was added at a rate to maintain the temperature at -10 to 5 °C with slight nitrogen bleed. The reaction was then heated to 20-25 °C over at least 60 min and purged with nitrogen to remove any traces of hydrogen. The resulting aluminum solids were filtered and washed with tetrahydrofuran (2  86 L). The tetrahydrofuran was displaced with 2-propanol until a temperature of at least 78 °C and a reaction volume was of 460-540 L were achieved. The reaction was cooled to 65-75 °C, and concentrated HCl (28.9 kg, 294 mol) was added over at least 60 min. The displacement was continued until additional 2-propanol (1060 L) was added and the final temp was at least 81 °C and the final volume was 390-460 L. The reaction was cooled to between 65 and 75 °C and granulated for at least 2 h. The reaction was cooled to between 15 and 25 °C, and a sample was pulled to ensure that the water content was <1%. After stirring at least2hat15-25 °C, the solids were filtered and washed with 2-propanol (85 L). After drying under vacuum for at least 12 h at 40-50 °C with a slight nitrogen bleed (cis-N-benzyl-3-methylamino-4-methypiperidine bis-(hydrochloride) (35.5 kg, 122 mol) was isolated in 87.1%yield (99.3% cis and 0.70% trans by GC) mp: 261.3-267.0 °C. 1H NMR (400 MHz, 1:1 CD3CN:D2O): ä 7.51-7.43 (m, 5H), 4.36-4.27 (m, 2H), 3.62-3.59 (m, 2H), 3.24- 3.13 (m, 3H), 2.65 (s, 3H), 2. (m, 1H), 1.95-1.91 (m, 1H), 1.82-1.75 (m, 1H), 1.03 (d, J ) 7.5 Hz, 3H). 13C NMR (1:1 CD3CN:D2O): 131.8, 130.5, 129.6, 128.6, 118.7, 61.0, 55.8, 46.4, 31.3, 27.5, 26.0, 10.0. Anal. Calcd for C14H24-Cl2N2: C, 57.73; H, 8.31; N, 9.62. Found: C, 57.77; H, 8.30; N, 9.60.

Preparation of bis-(3R,4R)-(1-benzyl-4-methyl-piperidine-3-yl)-methylamine di-p-toluoyl-L-tartaric acid

To a clean, dry, nitrogen-purged 250 ml flask were charged racemic cis-(1-benzyl-4-methyl-piperidine-3-yl)-methylamine bis hydrochloride (20.0 g, 68.7 mmol), di-p-toluoyl-L-tartaric acid (L-DPTT) (15.9 g, 41.2 mmol) and methanol (100 ml). A solution of sodium hydroxide (5.5 g, 137.3 mmol in water (100 ml)) was added to the reaction at a rate to maintain the temperature below 30° C. The reaction was heated to between 70-80° C. and held at this temperature for at least 60 minutes. The reaction was cooled to 5-15° C. over at least 4 hours and held at this temperature for at least 12 hours. The solids were filtered and washed with a 1:1 mixture of MeOH:water (60 ml). The wet-cake was returned to the 250 ml flask and methanol (100 ml) and water (100 ml) were charged. The reaction was heated to between 70-80° C. and held at this temperature for at least 120 minutes. The reaction was cooled to 5-15° C. over at least 4 hours and held at this temperature for at least 12 hours. The solids were filtered and washed with a 1:1 mixture of MeOH:water (60 ml). The wet-cake was sampled for purity (99.4% ee) to ensure an additional repulp was not necessary. After drying under vacuum at 40-50° C. for at least 24 hours with a slight nitrogen bleed, the title compound (11.9 g, 28.9 mmol) was isolated in 42.1% yield (98.6% enantiomeric excess, 0.63% trans isomer by GC (Cyclosil B column 30 m×I.D. 0.25 mm; Inlet Temp 250; 2.0 ml/min flow rate; 15 min run; 160 C isothermal method.

Preparation of N-[(3R,4R)-1-benzyl-4-methylpiperidin-3-yl]-2-chloro-N-methyl-7H-pyrrolo[2,3-d]pyrimidin-4-amine 

To a clean, dry, nitrogen-purged 500 ml reactor were charged 2,4-dichloro-7H-pyrrolo[2,3-d]pyrimidine, prepared as described below, (20.0 g, 0.106 mol), bis-(3R,4R)-(1-benzyl-4-methyl-piperidine-3-yl)-methylamine di-p-toluoyl-L-tartaric acid (20 g, 0.106 mol), potassium carbonate (44.6 g, 0.319 mol) and water (200 ml). The reactor was heated to 95-105° C. for a minimum of 10 hours then cooled to 20-30° C. and held for a minimum of 3 hours. The resulting solids were isolated by filtration, washed with water (60 ml) and dried at 50° C. to afford 39.5 g (100%) of the title compound.

Anal. Calcd. for C20H24ClN5: C, 64.94; H, 6.54; N, 18.93; Found: C, 64.78; H, 6.65; N, 18.83. 1H NMR (400 MHz, d6-acetone): δ 10.80 (bs, 1H), 7.36 (d, J=7.0 Hz, 2H), 7.30 (t, J=7.0 Hz, 2H), 7.24-7.20 (m, 1H), 7.13 (d, J=3.7 Hz, 1H), 6.66 (bs, 1H), 5.15 (bs, 1H), 3.69 (bs, 3H), 3.54 (ABq, J=13.3 Hz, 1H), 3.50 (ABq, J=13.3 Hz, 1H), 2.92 (dd, J=12.0, 5.4 Hz, 1H), 2.88-2.83 (m, 1H), 2.77 (bs, 1H), 2.64-2.59 (m, 1H), 2.29 (bs, 1H), 2.16 (bs, 1H), 1.75-1.69 (m, 2H), 0.94 (d, J=6.6 Hz, 3H). 13C NMR (400 MHz, d6-DMSO, mixture of Isomers): 158.0, 152.5, 151.8, 138.3, 129.1, 128.6, 128.1, 127.6, 126.8, 121.0, 102.3, 100.8, 62.5, 54.6, 53.1, 50.8, 35.3, 32.0, 30.9, 15.3.

Preparation of 2,4-dichloro-7H-pyrrolo[2,3-d]pyrimidine

A reactor was equipped with 7H-pyrrolo[2,3-d]pyrimidine-2,4-diol(10.0g, 66.2 mmol) and toluene (30 ml) with stirring. Phosphorusoxychloride (18.5 ml, 198.5 mmol) was added and the reactor was warmed to 700C. Diisopropylethylamine (23.0 m, 132.3 mmol) was added over 2.5 h to control the exotherm. After completion of the base addition, the reactor was heated to 1060C and stirred at temperature for 16 h. The mixture was cooled to 250C and added slowly to a flask containing water (230 ml) and ethyl acetate (120ml) at room temperature, then stirred overnight at room temperature. After filtration through Celite, the layers were separated the aqueous layer was extracted with ethyl acetate (3 x 75ml). The organic layers were combined and washed with brine (100ml). Darco KBB (1.24 g) was added to the organics, then filtered through Celite and dried over sodium sulfate (10.0 g). The solution was concentrated in vacuo to obtain the title compound (52% yield).

Preparation of methyl-[(3R,4R)-4-methyl-piperidin-3-yl]-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)amine

To a clean, dry, nitrogen-purged 500 ml hydrogenation reactor were charged 20 wt % Pd(OH)2/C (palladium hydroxide on carbon) (5.0 g, 50% water wet), water (200 ml), and N-((3R,4R)-1-benzyl-4-methylpiperidin-3-yl)-2-chloro-N-methyl-7H-pyrrolo[2,3-d]pyrimidin-4-amine (50.0 g, 0.135 mol). The reactor was purged three times at 50 psi with nitrogen and three times at 50 psi with hydrogen. Once purging was complete, the reactor was heated to 70-75° C. and pressurized to 50 psi with hydrogen through a continuous feed. The hydrogen uptake was monitored until no hydrogen was consumed for a minimum of 1 hour. The reactor was cooled to 20-30° C. and purged three times at 50 psi with nitrogen. The reaction mixture was filtered through water-wet Celite and transferred to a clean, dry, nitrogen-purged 500 ml reactor for subsequent processing.

Mp 158.6-159.8° C. 1H NMR (400 MHz, CDCl3): δ 11.38 (bs, 1H), 8.30 (s, 1H), 7.05 (d, J=3.5 Hz, 1H), 6.54 (d, J=3.5 Hz, 1H), 4.89-4.87 (m, 1H), 3.39 (s, 3H), 3.27 (dd, J=12.0, 9.3 Hz, 1H), 3.04 (dd, J=12.0, 3.9 Hz, 1H), 2.94 (td, J=12.6, 3.1 Hz, 1H0, 2.84 (dt, J=12.6, 4.3 Hz, 1H), 2.51-2.48 (m, 1H), 2.12 (bs, 2H), 1.89 (ddt, J=13.7, 10.6, 4 Hz, 1H), 1.62 (dq, J=13.7, 4Hz, 1H), 1.07 (d, J=7.3 Hz, 3H). 13C NMR (400 MHz, CDCl3): δ 157.9, 152.0, 151.0, 120.0, 103.0, 102.5, 56.3, 46.2, 42.4, 34.7, 33.4, 32.4, 14.3.

Preparation of 3-{(3R,4R)-4-methyl-3-[methyl-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-amino]-piperidin-1-yl}-3-oxo-propionitrile citrate salt (Tofacitinib citrate, Xeljanz, CP-690550-10)

To a round-bottomed flask fitted with a temperature probe, condenser, nitrogen source, and heating mantle, methyl-[(3R,4R)-4-methyl-piperidin-3-yl]-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-amine (5.0 g, 20.4 mmol) was added followed by 1-butanol (15 mL), ethyl cyanoacetate (4.6 g, 40.8 mmol), and DBU (1.6 g, 10.2 mmol). The resulting amber solution was stirred at 40 °C for 20 h. Upon reaction completion, citric acid monohydrate (8.57 g, 40.8 mmol) was added followed by water (7.5 mL) and 1-butanol (39.5 mL). The mixture was heated to 81 °C and held at that temperature for 30 min. The mixture was then cooled slowly to 22 ºC and stirred for 2 h. The slurry was filtered and washed with 1-butanol (20 mL). The filter cake was dried in a vacuum oven at 80 °C to afford 9.6 g (93%) of tofacitinib citrate as an off-white solid.

1H NMR (500 MHz, d6-DMSO): δ 8.14 (s, 1H), 7.11 (d, J=3.6 Hz, 1H), 6.57 (d, J=3.6 Hz, 1H), 4.96 (q, J=6.0 Hz, 1H), 4.00-3.90 (m, 2H), 3.80 (m, 2H), 3.51 (m, 1H), 3.32 (s, 3H), 2.80 (Abq, J=15.6 Hz, 2H), 2.71 (Abq, J=15.6 Hz, 2H), 2.52-2.50 (m, 1H), 2.45-2.41 (m, 1H), 1.81 (m, 1H), 1.69-1.65 (m, 1H), 1.04 (d, J=6.9 Hz, 3H).


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