Synthesis of the first thiazolidine-condensed five-, six-, and seven-membered heterocycles via cyclization of vinylogous N-acyliminium ions

Abstract

Synthesis of new thiazolidine-fused five-, six-, and seven-membered heterocycles through vinylogous N-acyliminium ion-cyclization sequence, involving positions 3 and 4 of the thiazolidine ring, is described. The formation of bicyclic products, arising by generally disfavored 5-endo-trig cyclization initiated by sulfur atom acting as a nucleophile, indicates the preparative value of this method.