Condensation of Thiourea Derivatives with Carbonyl Compounds: One‐Pot Synthesis of N‐Alkyl‐1,3‐thiazol‐2‐amines and of 3‐Alkyl‐1,3‐thiazolimines.

The reactions of ketones and N-substituted thioureas, in the presence of HCl (or HBr) and DMSO afford mixtures of the title compounds which are easily separated on a silica gel column. This method avoids the classical use of α-haloketones. The mechanism of these reactions involves the enolization of ketones and the activation of thiourea sulfur, probably by oxygen transfer from DMSO.