For the first time a reaction intermediate has been isolated giving further insight into the mechanism of thiazol-2-imine formation. The first step of the reaction requires a basic medium, while the second step is an acid mediated E1 elimination reaction. An efficient one- pot synthesis of substituted thiazol-2-imines have been achieved by the condensation of carbonyl compounds with thioureas and 1, 3-disubstituted thioureas using 1, 1′-(ethane- ...