Reaction of heterocyclic thioamides with dimethyl acetylenedicarboxylate. Synthesis of novel 2-azolyl-5-methoxycarbonylmethylene thiazolin-4-ones

A systematic study of the reactions of dimethyl acetylenedicarboxylate (DMAD) with heterocyclic thioamides has been carried out and a number of new 2-isoxazolyl-(8), imidazolyl-(13a,b and 17a), 1,2,3-triazolyl-(13d,e) and 1,2,3-thiadiazolyl (17b) thiazolines have been prepared. The higher reactivity of the thioamide group in comparison with the amino group in these reactions has been established.