Synthesis of 2‐isopropylidenehydrazinylthiazole and its subsequent annelation to the corresponding thiazolo[2,3‐c]‐s‐triazole

Abstract

An unequivocal synthesis of a new thiazolo[2,3‐c]‐s‐triazole substituted at the C‐5 position by a very useful methyl triphenylphosphonium salt has been achieved starting from the corresponding 2‐isopropylidenehydrazinylthiazole and formic acid. Ring closure was found to be very easy without isolation of a formylhydrazino intermediate. The thiazole derivative was prepared from isopropylidenethiosemicarbazide and (3‐chloro‐2‐oxo)propyltriphenylphosphonium chloride in a good yield.