2,3,5,6-Tetrahydro- and 5,6-dihydro-imidazo[2,1-b]thiazoles from imidazoline-2-thiol derivatives and unsaturated or halogenated acids and esters

Abstract

Evidence is presented to show that the products of reactions of imidazoline-2-thiol with acetylenedicarboxylic acid and its dimethyl ester are derivatives of 5,6-dihydroimidazo [2,1-b]thiazole-3(2H)-one. Other derivatives of this ring system are obtained by reactions of imidazoline-2-thiol with maleic anhydride and with α-bromo-dicarboxylic acids and their diethyl esters. Ethyl 2-chloro- and 4-bromoacetoacetate with imidazoline-2-thiol give derivatives of 5,6-dihydroimidazo[2,1-b]thiazole with retention of the ethoxycarbonyl group. 5-Substituted 2-thiohydantoins react in a similar way.