Methanol → 1-((3R)-6,8-Difluoro-3,4-dihydro-2H-1-benzopyran-3-yl)-1,3-dihydro-5-(2-((phenylmethyl)amino)ethyl)-2H-imidazole-2-thione

Participants

Reaction Steps

To a solution of potassium hydroxide (5M aqueous solution, 52.5 ml, 263 mmol) in water at 10° C. was added dropwise 2-mercaptoacetic acid (8.30 ml, 119 mmol). The resulting solution was stirred at room temperature for 10 minutes and a solution of (R)—N-benzyl-N-(2-(3-(6,8-difluorochroman-3-yl)-2-thioxo-2,3-dihydro-1H-imidazol-4-yl)ethyl)-2-nitrobenzenesulfonamide (28 g, 47.7 mmol) in DMSO (150 ml) was added dropwise over 20 minutes. During the addition of KOH, an exothermic event was observed. The resulting slurry was stirred at 40° C. under HPLC control for 3 h. The reaction was then cooled to 20° C. and methanol (105 ml) was added followed by water (45 ml). The resulting slurry was aged for 30 minutes at 20° C. and then filtered. The beige solid was successively washed with water/MeOH (9:1) (100 ml), water (200 ml) and finally methyl tert-butyl ether (MTBE) (50 ml), dried to give (R)-5-(2-(benzylamino)ethyl)-1-(6,8-difluorochroman-3-yl)-1H-imidazole-2(3H)-thione (compound RY′, 18.3 g, 12.35 mmol, 96% yield).

Provenance & Evidence