Boron tribromide → N-Acetyl-5-hydroxy-3,4,6-trimethylindoline

Participants

Reaction Conditions

Reaction Steps

Boron tribromide (1.4 mL of 1M solution in methylene chloride, 1.4 mmol) was added to a cooled (-78° C.) solution of indoline 9 (110 mg, 47 mmol) dissolved in methylene chloride (2 mL). The resulting solution was maintained at -78° C. (1 h), then slowly warmed to room temperature and held there for 17 h. The cooled reaction mixture was quenched with a few drops of methanol followed by cold water. The solution was extracted with methylene chloride and the combined organic layers were washed with brine and dried (MgSO4). Removal of solvents gave a solid, which was recrystallized from methylene chloride-hexanes to afford the indoline 11a (95 mg, 92% yield) as a colorless solid, mp 204°-205° C. Spectral data: 13C NMR (CD3SOCD3): δ 12.3, 17.2, 20.7, 23.7, 33.4, 56.4, 115.3, 120.7, 122.6, 133.9, 134.3, 149.1, 167.4; HRMS: calcd. for C13H17NO2 219.1259, fnd. 219.1261. Anal: calcd. for C13H17NO2C, 71.21, H, 7.81, N, 6.39, fnd. C, 71.06,H, 7.84, N, 6.33.

Provenance & Evidence