Pyridine → 5-Bromoisatoic Anhydride

Participants

Reaction Steps

A solution of 2-amino-5-bromo-benzoic acid (280 g, 1.3 mol) in acetonitrile (1.3 l) was warmed up to 50–55° C. Pyridine (206 g, 2.61 mol) and a solution of triphosgene (128.8 g, 0.43 mol) in dichloromethane (720 ml) were simultaneously added dropwise. After completion of the addition, the mixture was stirred at 50–55° C. for an additional 2 h. The solvent was removed under reduced pressure and water was added. The precipitate was collected by filtration, successively washed with water and chilled dichloromethane, and then dried under vacuum to afford the desired product 6-bromo-1H-benzo[d][1,3]oxazine-2,4-dione (304 g, 98%). This material was used in the next step without further purification.

Provenance & Evidence