Reaction Steps
(4aS,13aR)—N-[(2,4-Difluorophenyl)methyl]-10-hydroxy-9,11-dioxo-2,3,4a,5,9,11,13,13a-octahydro-1H-pyrido[1,2-a]pyrrolo[1′,′: 3,4]imidazo[1,2-d]pyrazine-8-carboxamide. A pressure reaction vessel was charged with (4aS,13aR)—N-[(2,4-Difluorophenyl)methyl]-9,11-dioxo-10-[(phenylmethyl)oxy]-2,3,4a,5,9,11,13,13a-octahydro-1H-pyrido[1,2-a]pyrrolo[1′,2′:3,4]imidazo[1,2-d]pyrazine-8-carboxamide (950 g), 192 g of palladium on carbon (50% wet), ethanol (9.5 L) and concentrated ammonium hydroxide (124 mL). The mixture was degassed with nitrogen 3 times and then placed under 50 psi of hydrogen until the reaction was complete. The mixture was degassed again with nitrogen and then filtered through Celite. The cake was extracted with refluxing dichloromethane and then filtered again. The combined filtrates were concentrated to a small volume (4 L), azeotroped with ethanol (28.5 L) to a final volume of 9 L. The slurry was filtered and washed with ethanol and dried to produce (4aS,13aR)—N-[(2,4-difluorophenyl)methyl]-10-hydroxy-9,11-dioxo-2,3,4a,5,9,11,13,13a-octahydro-1H-pyrido[1,2-a]pyrrolo[1′,2′: 3,4]imidazo[1,2-d]pyrazine-8-carboxamide (616 g, 78.4%) as a white solid. 1H NMR (300 MHz, DMSO-d6) δ ppm 10.37 (m, 1H), 8.42 (s, 1H), 7.41-7.05 (m, 3H), 4.72-4.53 (m, 4H), 4.05 (m, 1H), 3.86 (m, 1H), 3.70 (m, 1H), 3.16 (m, 1H), 2.88 (m, 2H), 1.92-1.60 (m, 4H).
