Simple synthesis, structure and ab initio study of 1,4-benzodiazepine-2,5-diones

A simple procedure for the synthesis of pyrido[2,1-c][1,4] benzodiazepine-6,12-dione (1) and 1,4-benzodiazepine-2,5-diones (2a–2d), using microwave irradiation and/or conventional heating is reported. The configuration of 1 was determined by single-crystal X-ray diffraction. A detailed ab initio B3LYP/6-31G* calculation of structural parameters and substituent effects on ring inversion barriers ðDG#Þ and also free energy differences ðDG0Þ for benzodiazepines are reported. q 2004 Elsevier B.V. All rights reserved