Hydrochloric Acid → 2-oxo-2,3-Dihydrobenzooxazole-5-boronic acid

Participants

Reaction Conditions

Reaction Steps

Add n-BuLi (1.6M in hexanes, 8.76 mL, 14.02 mmol) portionwise (exotherm) to a solution of 5-bromo-3H-benzooxazol-2-one (1.00 g, 4.67 mmol) in dry THF (28 mL) at −78° C. under N2. Stir at −40° C. for 1 h and add trimethylborate (1.94 g, 18.68 mmol) at once. Warm up to room temperature overnight. Add 1N aqueous HCl (50 mL) and stir for 3 h at room temperature. Extract into ethyl acetate, dry (MgSO4) and concentrate organics to a brown solid. Triturate with hexanes/toluene and collect 766 mg (92%) of the title compound as a brown powder. MS (ES) 179 (M+H), 177 (M−H); HPLC shows 80% purity.

Provenance & Evidence