UNEXPECTED TRANSFORMATION OF 1,5-BENZODIAZEPINE DERIVATIVES UNDER IMIDAZO-ANNULATION REACTION CONDITIONS

Abstract

In an attempt to synthesize new derivatives of imidazo[1,5-a][1,5]benzodiazepine-3-carboxylic acid esters by activation of the amide group of the heterocycle to iminophosphate and its cyclocondensation with ethyl isocyanoacetate, unexpected 5-substituted ethyl oxazole-4-carboxylates were obtained as the main products. Structures of the novel oxazole derivatives were confirmed by IR, ¹H, ¹³C, and ³¹P NMR, and mass spectra, and the reaction course was rationalized using computational molecular modeling techniques.