The synthesis of a series of allyl substituted 3-thiazoline-carboxylates was carried out from the corresponding thiazolidines, by a MnO2-mediated oxidation reaction under mild conditions. The reaction was chemoselective towards the amine-imine oxidation and was also regioselective, affording the unsaturation at the 3-position of the heterocycle. (C) 2001 Published by Elsevier Science Ltd.