Ammonium Hydroxide → N-(3-((4aS,5S,7aS)-2-amino-5-(trifluoromethyl)-4a,5,7,7a-tetrahydro-4H-furo[3,4-d][1,3]thiazin-7a-yl)-4-fluorophenyl)-5-(fluoromethyl)pyrazine-2-carboxamide

Participants

Reaction Conditions

Reaction Steps

5-(Fluoromethyl)pyrazine-2-carboxylic acid (32.6 g, 1.05 equiv) and (4aS,5S,7aS)-7a-(5-amino-2-fluorophenyl)-5-(trifluoromethyl)-4a,5,7,7a-tetrahydro-4H-furo[3,4-d][1,3]thiazin-2-amine (70.0 g, 1.0 equiv)1 were charged to a reactor and ethyl acetate (EtOAc, 630 mL) was added to the mixture to give a suspension. A solution of n-propane phosphonic acid anhydride (T3P, 146 g, 1.10 equiv, 50 wt % in EtOAc) was added at ambient temperature while controlling the internal temperature below 30° C. The reaction mixture was stirred at 40−45° C. >3 hours and monitored by HPLC. The reaction mixture was cooled to 15−20° C. and water (140 mL) was charged. After 10-15 minutes charged 28% ammonium hydroxide (175 mL) while controlling the temperature below 30° C. EtOAc (245 mL0 was added and the reaction mixture was stirred for 30 minutes at ambient temperature. The aqueous phase was separated and back-extracted with EtOAc (490 mL). The organic phases were combined and washed with 15% aq. NaCl (140 mL) and water (140 mL). The organic layer was filtered over Celite (1.0 Wt) and rinsed with EtOAc (140 mL). The solution was concentrated under vacuum to obtain a beige solid (quantitative crude yield) which was recrystallized from 1-propanol to afford N-(3-((4aS,5S,7aS)-2-amino-5-(trifluoromethyl)-4a,5,7,7a-tetrahydro-4H-furo[3,4-d][1,3]thiazin-7a-yl)-4-fluorophenyl)-5-(fluoromethyl)pyrazine-2-carboxamide as a white solid (70.0 g). 1 A preparation of (4aS,5S,7aS)-7a-(5-amino-2-fluorophenyl)-5-(trifluoromethyl)-4a,5,7,7a-tetrahydro-4H-furo[3,4-d][1,3]thiazin-2-amine is described herein above in step 1-(25) in the alternative preparation of N-(3-((4aS,5S,7aS)-2-amino-5-(trifluoromethyl)-4a,5,7,7a-tetrahydro-4H-furo[3,4-d][1,3]thiazin-7a-yl)-4-fluorophenyl)-5-methoxypyrazine-2-carboxamide (Example 1).

Provenance & Evidence