Reaction Steps
[(3S)-3-Aminobutyl]cyclobutylamine dihydrochloride was prepared in a similar manner as described in example Z-47, 1H NMR (400 MHz, CDCl3/CD3OD) δ 1.23 (d, J=6.4 Hz, 3H), 1.69-2.26 (m, 8H), 2.83 (m, 2H), 3.31-3.33 (m, 1H), 3.55 (m, 1H), 8.08 (br, <1H), 9.07 (br, <1H). b) (4S,12aS)-1Cyclobutyl-N-[(2,4-difluorophenyl)methyl]-7-hydroxy-4-methyl-6,8-dioxo-1,2,3,4,6,8,12,12a-octahydropyrido[1′,2′:4,5]pyrazino[1,2-a]pyrimidine-9-carboxamide. The title compound was made in two steps using a similar process to that described in example Z-2. 16a (80 mg, 0.17 mmol) and free based [(3S)-3-aminobutyl]cyclobutylamine (96 mg, 0.68 mural) were reacted in dichloromethane (2 in L) with acetic acid to give (4S,12aS)-1-cyclobutyl-N-[(2,4-difluorophenyl)methyl]-4-methyl-6,8-dioxo-7-[(phenylmethyl)oxy]-1,2,3,4,6,8,12,12a-octahydropyrido[1′,2′:4,5]pyrazino[1,2-a]pyrimidine-9-carboxamide (68 mg, 70%) as a film. This material was hydrogenated in a second step as described in example Z-2 to give (4S,12aS)-1-cyclobutyl-N-[(2,4-difluorophenyl)methyl]-7-hydroxy-4-methyl-6,8-dioxo-1,2,3,4,6,8,12,12a-octahydropyrido[1′,2′:4,5]pyrazino[1,2-a]pyrimidine-9-carboxamide (57 mg, 100%) as an off-white solid, 1H NMR (4.00 MHz, CDCl3) δ 1.31 (d, J=6.8 Hz, 3H), 1.46-1.70 (m, 4H), 1.91-2.12 (m, 4H), 2.52 (m, 1H), 2.90-2.93 (m, 1H), 3.06 (m, 1H), 4.16-4.29 (m, 3H), 4.57-4.66 (m, 2H), 4.99-5.05 (m, 1H), 6.75-6.82 (m, 2H), 7.32-7.38 (m, 1H), 8.20 (s, 1H), 10.44 (s, 1H), 12.51 (s, 1H); ES+ MS: 473 (M+1).
