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.
Key words
epoxides - anthranilic acids - click reaction - solvent-free - grinding - 4,1-benzoxazepines
- cascade reactions
