Thiazolidin-4-one formation. Mechanistic and synthetic aspects of the reaction of imines and mercaptoacetic acid under microwave and conventional heating

Microwave irradiation of a mixture of benzylidene-anilines and mercaptoacetic acid in benzene gives 1,3-thiazolidin-4- ones in very high yield (65–90%), whereas the same reaction performed through using the conventional method, at refluxtemperature, requires a much longer time and gives a much lower yield (25–69%). This difference seems to be due to someintermediates and by-products formed during the conventional reaction. On the basis of 1H NMR studies, two differentmechanisms, acting in benzene and in DMF, respectively, have been hypothesized for the thiazolidin-4-one system formation.