Facile synthesis of benzo[e][1,2,4]triazepin-5-ones through a base medicated [4+3] cycloaddition

Herein, we report the synthesis of highly functionalized benzo[e][1,2,4]triazepin-5-ones through a base medicated [4 + 3] cycloaddition of hydrazonoyl chloride and isatoic anhydride. The reaction proceeds through in situ generated nitrile imines from easily accessible hydrazonoyl chlorides. a simple organic base triethyl amine drives the reaction very successfully to give the desired products in excellent yields. The robustness of the [4 + 3] cycloaddition process is well evidented by broad substrate scope.