Unexpected result for the acylation of arylhydrazonoethanethioamides

Abstract

The acylation of arylhydrazonoethanethioamides containing primary amino group did not yield acylthioamides as expected. Surprisingly, the cyclic 5-acylimino-2,5-dihydro-1,2,3-thiadiazoles were obtained. The formation of thiadiazoles in this reaction was explained by the higher ability of arylhydrazono-N-acylthioacetamide intermediates to be oxidized comparing to their precursors. The presence of pseudobicyclic aromatic structure in the reaction product was a main factor favoring the formation of 1,2,3-thiadiazole ring. © 2013 Elsevier Ltd. All rights reserved.