Synthesis of 1,3,4-thiadiazole oligomers

Abstract

A range of hydrazono chlorides 8, readily prepared from 5-substituted tetrazoles 7 and Appel salt 1, are rapidly converted by triphenylphosphine into 5-cyano-1,3,4-thiadiazoles 9 in high yield. These cyanides are converted by azide into the corresponding tetrazoles 10 which with Appel salt give the hydrazono chlorides 11 which are similarly converted by triphenylphosphine into the bi-1,3,4-thiadiazolyls 12a,c,g, all in high yield. Repetition of the 3-step sequence (12 → 13 → 14 → 15) gives the ter-1,3,4-thiadiazolyls 15a,g.