Synthesis of 2-substituted 3,4-dihydro-1,2-diazepines by the reactions of unsaturated ketones with hydrazides

Abstract

The previously reported synthesis of 3,4-dihydro-2-tosyl-1,2-diazepines by the acid-catalysed reactions of p-toluenesulphonylhydrazide with αβ,γδ-unsaturated ketones has been extended to other 2-substituted analogues (3) by the use of a variety of hydrazine derivative. A new acid-catalysed ring contraction, the conversion of 2-benzoyl-3,4-dihydro-1,2-diazepine (3d) into 1-benzoyl-3-methylpyrazol-2-ine (4), is also reported.