A novel approach for the synthesis of functionalized 1,5-benzodiazepine is described. The protocol is triggered by a tandemconjugatedaddition/cyclizationprocess from the readily available starting materials 1,2-phenylenediamine and ethyl propiolate. The products have secondary amino and ester groups, and a β-enamino ester, which can serve in further functionalizations to produce molecular diversity
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. (C) 2009 Elsevier Ltd. All rights reserved.