A new [3 + 4] cycloaddition of azaoxyallyl cations and anthranils has been achieved for rapid access to multisubstituted benzodiazepine derivatives. A variety of anthranils and α-halo hydroxamates were both effective substrates with simple operations under transition-metal-free conditions. The intriguing features of this method include its mild nature of the reaction conditions, high efficiency, broad substrate scope, and wide functional group compatibility.