Gallium(III) triflate-catalyzed [4+2+1] cycloadditions for the synthesis of novel 3,4-disubstituted-1,5-benzodiazepines

Gallium(III) triflate-catalyzed [4+2+1] cycloaddition of o-phenylenediamines and 2 equiv of alkynoate under solvent-free and ultrasonic irradiation conditions afforded novel 3,4-disubstituted-1,5-benzodiazepines in 82-90% yields.