Hydrochloric Acid → Methyl [(2S)-3-methyl-1-{(2S,4S)-4-methyl-2-[9-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1,11-dihydroisochromeno[4',3':6,7]naphtho[1,2-d]imidazol-2-yl]pyrrolidin-1-yl}-1-oxobutan-2-yl]carbamate

Participants

Reaction Steps

(2S,4S)-tert-butyl 4-methyl-2-(9-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1,11-dihydroisochromeno [4′,3′:6,7] naphto[1,2-d]imidazol-2-yl)pyrrolidine-1-carboxylate (950 mg, 1.63 mmol) was dissolved in DCM (12 mL), MeOH (3 mL) and HCl (4 M in dioxane, 3 mL) was added. The reaction mixture was stirred for 4 h and then concentrated under reduced pressure. The crude residue was treated with (S)-2-(methoxycarbonylamino)-3-methylbutanoic acid (285 mg, 1.63 mmol), HATU (620 mg, 1.63 mmol) and DMF (15 mL), then DIPEA (1.42 mL, 8.15 mmol) was added dropwise. After 1 h, the mixture was diluted with EtOAc and washed successively with saturated aqueous NaHCO3 and brine. The organics were dried over MgSO4, filtered and concentrated under reduced pressure. The crude residue was purified by silica column chromatography (0% to 30% MeOH/EtOAc) to afford methyl [(2S)-3-methyl-1-{(2S,4S)-4-methyl-2-[9-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1,11-dihydroisochromeno[4′,3′:6,7]naphtho[1,2-d]imidazol-2-yl]pyrrolidin-1-yl}-1-oxobutan-2-yl]carbamate (596 mg, 57%).

Provenance & Evidence