Click Reaction of Epoxides with Anthranilic Acids Using Neat Grinding To Access Benzoxazepines

An atom-economic, efficient, rapid (5 min), and highly regioselective one-pot click reaction has been developed for the synthesis of benzo[e][1,4]oxazepin-5-ones in excellent yields (78–92%). The method involves epoxide ring-opening–ring-closing cascade with anthranilic acids using neat grinding at room temperature in the presence of lithium bromide as a mild catalyst. In this procedure, pure products are obtained simply by washing the reaction mixture with warm water, thus hazardous solvents, tedious workup processes, and purification steps, such as column chromatography and recrystallization, are avoided.