tot-Butyl (2S,4S)-2-[5-(2-{(2S,5S)-l-[N-(methoxycarbonyl)-L-valyl]-5-methylpyrrolidin-2-yl}- l,ll-dihydroisochromeno[4',3':6,7]naphtho[l,2-d]imidazol-9-yl)-lH-imidazol-2-yl]-4- (methoxymethyl)pyrrolidine-l-carboxylate tert-Butyl (2S,4S)-2-[5-(2- {(2S,5S)-l-[N-(methoxycarbonyl)-L-valyl]-5-methylpyrrolidin-2- yl} -l ,4,5,l l-tetrahydroisochromeno[4',3':6,7]naphtho[l,2-d]imidazol-9-yl)-lH-imidazol-2-yl]-4- (methoxymethyl)pyrrolidine-l-carboxylate (8.33 g, 1.049 mmol) was suspended in DCM and activated Mn02 (55.0 g, 630 mmol) was added in a single portion. After 13 h, MeOH (200 mL) was added and the slurry was filtered over celite. The filter cake was washed with MeOH (600 mL) and the filtrate was concentrated under reduced pressure. The crude material was purified by silica column chromatography (0% to 45% MeOH/EtOAc) to afford tert-butyl (2S,4S)-2-[5-(2- {(2S,5S)-l-[N- (methoxycarbonyl)-L-valyl] -5 -methylpyrrolidin-2-yl} -1,11- dihydroisochromeno[4',3':6,7]naphtho[l,2-d]imidazol-9-yl)-lH-imidazol-2-yl]-4- (methoxymethyl)pyrrolidine-l-carboxylate (4.85 g, 58%).
