Regioselectivity of [3+2] Cycloadditions of Heteroaryl Azides and Ethyl‐Vinyl Ether

Abstract

AbstractThe reaction of ethyl vinyl ether with some heteroaryl azides in the presence of MnSO4 affords some unexpected products. In the case of 2‐azido‐1,3‐thiazole an imidate is formed, while 2‐azidobenzothiophene gives an unprecedented 3,3a‐dihydro‐2H‐8‐thia‐1‐aza‐cyclopenta[a]indene system, with loss of the aromaticity of the benzotiophene ring. DFT calculations are performed to justify these structures. Selenophene ‐derived acyl azides on the contrary, afford in two cases N‐heteroaryl carbamates, probably due to the reaction of an intermediate isocyanate and cleavage of the ether linkage.