Studies in the synthesis and interconversion of isomeric triazolothienopyrimidines

Abstract

Abstract 4‐Hydrazinothieno[2,3‐ d ]pyrimidines were cyclized with triethyl orthoformate and formic acid to give 1,2,4‐triazolo[4,3‐ c ]thieno[3,2‐ e ]pyrimidines and 1,2,4‐triazolo[2,3‐ c ]thieno[3,2‐ e ]pyrimidines depending on the reaction conditions employed.