Carbon Dioxide → Emtricitabine

Participants

Reaction Steps

To a 250 mL round bottom flask, fitted with a magnetic stirrer, are added cis-(−)-4-amino-5-fluoro-1-(2-(hydroxymethyl)-1,3-oxathiolan-5-yl)-2(1H)-pyrimidinone HCl salt (5 g, 17.63 mmol, 99.4% purity) and methanol (25 mL). The mixture is stirred at room temperature, and to it is added Na2CO3 solid (1.12 g, 10.6 mmol). CO2 gas comes out immediately after the addition. Upon being stirred at room temperature for 3 hours, the reaction mixture is diluted with ethyl acetate (125 mL) and stirred at room temperature for 1 hour. Then the mixture is filtered through a silica gel-Celite pad, and the pad is washed with ethyl acetate-methanol (5:1, v/v) (20 mL). The filtrate is concentrated at 40-50° C. to 20 mL, and to it is added ethanol (5 mL). The resulting mixture is stirred at 60° C. for 15 minutes, then cooled to 0° C. and stirred at 0° C. for 1.5 hours. The mixture is filtered and the solid cake is washed with ethyl acetate. The solid is dried in vacuum at 45° C. for 12 hours to afford (−)-FTC as white solids (3.7 g, 86%, HPLC assay: 99.7% purity). The mother liquid is concentrated to 5 mL, and stirred at room temperature. Filtration gave (−)-FTC as white crystals (0.2 g, 4.7%).

Provenance & Evidence