反应详情

A mixture of 2-benzyloxycarbonylamino-4-chlorobenzoic acid (564 g) and phosphorus tribromide (1.5 kg) in diethyl ether (9 l) was refluxed for 40 hours and allowed to stand at room temperature for 5 days. The resulting precipitates were collected by filtration and washed in turn with diethyl ether (5 l) and ethanol (3 l) to give 7-chloro-2H-3,1-benzoxazine-2,4(1H)-dione (335 g).

1. temperaturewas refluxed for 40 hours
2. customThe resulting precipitates
3. filtrationwere collected by filtration
4. washwashed in turn with diethyl ether (5 l) and ethanol (3 l)