Synthesis of thiazoles from vinyl azides and xanthates under the action of an Mn(iii)-oxidant

Abstract

Reaction of xanthates and vinyl azides under the action of Mn(OAc)₃ results in the formation of alkoxy thiazoles. In this transformation, potassium xanthate undergoes Mn-mediated oxidation, generating the corresponding xanthyl radical. The latter interacts with the double bond of the vinyl azide, and after N₂ elimination, a β-xanthylated iminyl radical is formed. The quenching of the iminyl radical by an Mn(II)-ion with subsequent cyclization into a 5-membered ring, an unexpected elimination of a sulfur-containing fragment and aromatization lead to thiazoles. It is important to mention that cyclization with the formation of a 6-membered ring is not observed in the disclosed process. The obtained thiazoles demonstrate antifungal activity surpassing that of commercially available fungicides.