Synthesis of spiro[cyclopent-2/3-ene-1,2′-[1,3]thiazolo[3,2-a] pyrimidine] derivatives via 1,3-dipolar cycloaddition reaction of ethyl buta-2,3-dienoate

Abstract

The 1,3-dipolar cycloaddition reaction of ethyl (2Z)-5-aryl-2-(2-methoxy-2-oxoethylidene)-7-methyl-2,3-dihydro-5H-thiazolo[3,2-a] pyrimidine-6-carboxylate and ethyl buta-2,3-dienoate catalysed by triphenylphosphine afforded novel spiro[cyclopent-2-ene-1,2′-[1,3] thiazolo[3,2-a]pyrimidine] and spiro[cyclopent-3-ene-1,2′-[1,3]thiazolo[3,2-a]pyrimidine] derivatives in moderate yields. The structures of all the products were characterised thoroughly by NMR, IR and HRMS together with X-ray crystallographic analysis.