Methanesulfonic Acid → (S)-1-{[2-(5-methyl-2-phenyl-oxazol-4-yl)-ethylamino]-acetyl}-pyrrolidine-2-carbonitrile mesylate

참여 물질

반응 단계

A 1000 mL double jacketed glass reactor equipped with a mechanical stirrer, a Pt-100 thermometer, a reflux condenser, a dropping funnel and a nitrogen inlet was charged with 60 g (199.5 mmol) of 2-(5-Methyl-2-phenyl-oxazol-4-yl)-ethylammonium mesylate, 15.4 g (199.4 mmol) of calciumhydroxyde and 350 mL of DMA. The resulting suspension was heated to 25° C. to 30° C. and stirred for 15 to 60 min at this temperature. A solution of 27.5 g (159.6 mmol) of (S)-1-(2-chloroacetyl)-pyrrolidine-2-carbonitrile in 54.4 g of DMA was added-within 15 to 30 min and the dropping funnel was rinsed with 10 mL of DMA. The mixture was heated to 25° C. to 30° C. and stirred for 1 to 2 h at this temperature. The reaction mixture was cooled to RT and treated with 400 mL of methylenechloride and 300 mL of Water. The pH of the resulting mixture was set with 1M methanesulfonic acid (ca. 80 mL) to 7.8. The mixture was then stirred for about 30 min at RT. The phases were separated and the aqueous phase was extracted with 200 mL of methylenechloride. The combined organic layers were twice extracted with totally 400 mL of aqueous 1% NaCl solution. The organic phase was cooled to 5° C. to 15° C. and methanesulfonic acid (13.6 g, 139.7 mmol) was added within 5 min. Methylenechloride was completely removed first under normal pressure, then under vacuum (500-50 mbar) at a jacket temperature of maximal 55° C. While adding 700 mL of 2-butanone at 38° C. to 42° C. within 40 to 60 min to the resulting residue, the product precipitated and subsequently, 180 to 220 mL of 2-butanone were distilled off under vacuum (170 to 250 mbar). The resulting suspension was cooled to 10° C. within 3-4 h and stirred at this temperature for at least 2 h. The precipitate was filtered with suction, the filter cake was washed with 100 mL of cold 2-butanone (−10° C.) and dried under vacuum (50° C., 50 mbar) to afford about 61.3 g (yield 85% starting from of (S)-1-(2-chloroacetyl)-pyrrolidine-2-carbonitrile, 94.9% (m/m) purity based on HPLC assay) of (S)-1-{[2-(5-methyl-2-phenyl-oxazol-4-yl)-ethylamino]-acetyl}-pyrrolidine-2-carbonitrile mesylate as a colorless solid. The HPLC analysis was performed with an external standard of pure (S)-1-{[2-(5-methyl-2-phenyl-oxazol-4-yl)-ethylamino]-acetyl}-pyrrolidine-2-carbonitrile mesylate. Conditions for HPLC: Column XTerra RP8 Waters, 4.6×150 mm, 3.5 μm; UV detector 220 nm; solutions for gradient: water (A), acetonitrile (B), pH 6.5 buffer KH2PO4/K2HPO4 (C); flow 1.2 mL/min, 40° C.

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