Conversion of 4,6‐disubstituted pyrimidines into 1,2,4‐Triazoles by action of Hydrazine

Abstract
4,6‐Diethoxy‐, 4‐ethoxy‐6‐hydrazino‐, 4,6‐dichloro‐, 4,6‐di(methylthio)‐and 4,6‐dihydrazinopyrimidine react with aqueous hydrazine at 210° to give 3‐methyl‐1,2,4‐triazole. Evidence is presented that in this unprecedented ring contraction reaction the C(2)‐N(3 or 1)‐C(4 or 6)‐C(5) fragment of the pyrimidine ring is involved in the formation of this 1,2,4‐triazole.