In order to find new thiazole-heterocycle lead compounds, six 2-oxo/thio-1,3-thiazolidine- 3-carboxylates 3 and five N-substituted benzoyl-2-oxo/thio-1,3-thiazolidines 5 were synthesized from a condensation reaction of 2-oxo/thio-1,3-thiazolidine 1 and substituted phenyl chloroformates 2 or substituted benzoyl chlorides 4 in presence of Et₃N. Their structures were confirmed by ¹H NMR, IR, MS spectra and elemental analysis. The crystal structures of phenyl 2-thiono-1,3-thiazolidine-3-carboxylate (3d) and N-benzoyl-2- oxo-1,3-thiazolidine (5a) were determined by X-ray diffraction analysis, and the structure of the condensation products of 2-thiono-1,3-thiazolidine with substituted phenyl chloroformates was proved to be 2-thiono-1,3-thiazolidine-3-carboxylate rather than the ester of mercaptothiazoline. The preliminary bioassay showed that compounds 3 and 5 exhibited certain fungicidal and insecticidal activities.

Key words: substituted phenyl chloroformate, biological activity, substituted benzoyl chloride, structure, 2-oxo/thio-1,3-thiazolidine