Regio‐ and Chemoselectivity of Tandem N‐Ketoalkylation/Cyclization of 2‐Thioxoimidazoline‐4‐One

Abstract

The reaction of 2‐thioxoimidazolidin‐4‐one (thiohydantoin) with aliphatic, aromatic and heteroaromatic α‐iodomethylketones has been investigated in the absence of bases or catalysts. The reaction proceeds as N‐alkylation with subsequent intramolecular dehydrative cyclization. A series of new mono‐ and fused bicyclic iodide and triiodide salts was obtained based on the 5‐oxo‐2‐thioxoimidazolidin‐1‐ium and imidazo[2,1‐b]thiazolium cations. The observed regioselectivity has been rationalized and the mechanism was proposed.