Methanesulfonic Acid → 8-bromo-3,4-dihydrobenzo[f][1,4]oxazepin-5(2H)-one

Participants

Reaction Conditions

Reaction Steps

A solution of 7-bromochroman-4-one (340 mg, 1.5 mmol) and methanesulfonic acid (3 mL, 23.0 mmol) in DCM was cooled to 0° C. and treated with NaN3 (146 mg, 2.25 mmol) portionwise, while maintaining the internal temperature below 5° C. The reaction was then stirred at 0° C. for 4 h. At completion, the reaction was slowly neutralized with 8 N aq. NaOH, then diluted with DCM (20 mL) and water (20 mL). The layers were separated and the organics were dried over MgSO4, filtered and evaporated to afford 8-bromo-3,4-dihydrobenzo[f][1,4]oxazepin-5(2H)-one (370 mg, 100% yield). MS (EI) m/z=242.1 [M+1]+.

Provenance & Evidence