Reaction Steps
To a solution of tert-butyl (2S,4S)-2-[9-(2-{(2S,5S)-1-[N-(methoxycarbonyl)-L-isoleucyl]-5-methylpyrrolidin-2-yl}-1H-imidazol-5-yl)-1,11-dihydroisochromeno[4′,3′:6,7]naphtho[1,2-d]imidazol-2-yl]-4-(methoxymethyl)pyrrolidine-1-carboxylate (0.075 g, 0.09 mmol) in a mixture of CH2Cl2 (1.0 mL) and MeOH (0.25 mL) was added HCl (in dioxanes, 4M, 0.7 mL, 2.8 mmol). The solution was stirred at 40° C. for 1 h, cooled to room temperature, and then concentrated to dryness under reduced pressure. To the crude intermediate suspended in CH2Cl2 (3.0 mL) was added (S)-2-(methoxycarbonylamino)-3-methylbutanoic acid (0.020 g, 0.14 mmol), HATU (0.043 g, 0.11 mmol) and DIPEA (0.10 mL, 0.57 mmol). The reaction was stirred at room temperature for 2 h. The reaction was diluted with DMF and aqueous LiOH (2.5 M, 3 drops) and the CH2Cl2 was removed under reduced pressure. The crude residue was purified by preparative reverse phase HPLC (10% to 58% 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 {(2S)-1-[(2S,4S)-2-(9-{2-[(2S,5S)-1-{(2S,3S)-2-[(methoxycarbonyl)amino]-3-methylpentanoyl}-5-methylpyrrolidin-2-yl]-1H-imidazol-5-yl}-1,11-dihydroisochromeno[4′,3′:6,7]naphtho[1,2-d]imidazol-2-yl)-4-(methoxymethyl)pyrrolidin-1-yl]-3-methyl-1-oxobutan-2-yl}carbamate (0.031 g, 38%). 1H-NMR: 400 MHz, (MeOD) δ: (Mixture of rotomers) 8.34 (m, 1H), 7.91-9.97 (m, 2H), 7.50-7.81 (m, 3H), 7.35-7.38 (m, 2H), 5.17-5.26 (m, 3H), 5.08 (m, 1H), 4.14-4.33 (m, 4H), 3.64 (s, 3H), 3.63 (s, 3H), 3.51-3.59 (m, 3H), 3.37 (s, 3H), 2.71 (m, 1H), 2.55-2.59 (m, 1H), 2.23-2.33 (m, 1H), 1.92-2.10 (m, 2H), 1.77-1.89 (m, 1H), 1.60 (m, 1H), 1.48 (d, 1H), 1.11-1.22 (m, 2H), 0.81-0.98 (m, 12H). MS (ESI) m/z 864.27 [M+H]+.
