Reaction Steps
To a solution of tert-butyl (2S,4S)-2-[5-(2-{(1S,3S,5S)-2-[N-(methoxycarbonyl)-L-valyl]-2-azabicyclo[3.1.0]hex-3-yl}-1,11-dihydroisochromeno[4′,3′:6,7]naphtho[1,2-d]imidazol-9-yl)-1H-imidazol-2-yl]-4-(methoxymethyl)pyrrolidine-1-carboxylate (0.025 g, 0.032 mmol) in a mixture of CH2Cl2 (1.0 mL) and MeOH (0.25 mL) was added HCl (in dioxanes, 4M, 0.50 mL, 2.0 mmol). The solution was stirred at room temperature for 12 h, and then concentrated to dryness under reduced pressure. To the crude intermediate suspended in CH2Cl2 (0.5 mL) was added (R)-2-(methoxycarbonylamino)-2-phenylacetic acid (0.012 g, 0.057 mmol) and DIPEA (0.05 mL, 0.28 mmol). The resulting solution was cooled to 0° C. and COMU (0.023 g, 0.054 mmol) was added. The reaction was stirred at 0° C. for 30 min. The solution was diluted with DMF and aqueous LiOH (2.5 M, 2 drops) and concentrated under reduced pressure to remove the CH2Cl2. The crude residue was purified by preparative reverse phase HPLC (10% to 55% MeCN/water with 0.1% TFA). The desired fractions were combined and concentrated under reduced pressure to remove volatile organics. The addition of aqueous sodium bicarbonate with stirring resulted in precipitation of a white solid. The precipitate was filtered through a membrane filter and washed with water. Drying under reduced pressure afforded methyl {(1R)-2-[(2S,4S)-2-(5-{2-[(1 S,3S,5 S)-2-{(2S)-2-[(methoxycarbonyl)amino]-3-methylbutanoyl}-2-azabicyclo[3.1.0]hex-3-yl]-1,11-dihydroisochromeno[4′,3′:6,7]naphtho[1,2-d]imidazol-9-yl}-1H-imidazol-2-yl)-4-(methoxymethyl)pyrrolidin-1-yl]-2-oxo-1-phenylethyl}carbamate (0.015 g, 55%). 1H-NMR: 400 MHz, (MeOD) 6: (Mixture of rotamers) 8.35 (m, 1H), 7.94-7.96 (m, 2H), 7.54-7.78 (m, 6H), 6.93-7.00 (m, 1H), 5.72 (m, 1H), 5.46 (s, 1H), 5.19 (s, 2H), 5.14-5.16 (m, 1H), 3.95 (m, 1H), 3.67 (s, 3H), 3.63 (s, 3H), 3.42-3.49 (m, 2H), 3.24 (s, 3H), 2.67-2.78 (m, 2H), 2.41-2.62 (m, 3H), 2.01-2.13 (m, 2H), 1.86-1.99 (m, 3H), 0.99-1.03 (m, 2H), 0.90 (d, 3H). MS (ESI) m/z 882.23 [M+H]+.
