Highly efficient one-pot,three-component synthesis of 1, 5-benzodiazepine derivatives

A general, mild and efficient protocol for the synthesis of ethyl 4-methyl-2-(thiophen)-2,5-dihydro-1,5- benzodiazepine-3-carboxylate is achieved for first time using H3PMo12O40 in ethanol at 0 ℃ by a onepot, three-component condensation of various thiophene aldehydes, substituted o-phenylenediamines and ethyl acetoacetate. Compared with the conventional synthesis method, this procedure has the advantages of convenient operation, excellent yields, and environmentally benign. A plausible formation mechanism has been proposed. The structure of the products is characterized by 1H NMR, IR, MS and elemental analysis.