Zinc Tetrafluoroborate-Mediated Ring Expansion of -Aziridine-2-carboxylates to -2-Iminothiazolidines and -Thiazolidine-2-iminium Tetrafluoroborates and Evaluation of Antimicrobial Activity.

-2-iminothiazolidines and -thiazolidine-2-iminium tetrafluoroborates were successfully produced from --alkyl aziridine-2-carboxylates and phenyl/alkyl isothiocyanates mediated by zinc tetrafluoroborate in refluxing DCE. Reactions were performed via a complete regio- and stereoselective process to give the title iminothiazolidines and -thiazolidine-2-iminium salts in moderate to good yields (35 to 82%) with a wide substrate scope. In addition, the antibacterial activity evaluation of these compounds, as well as the minimum inhibitory concentration (MIC) determination, revealed that only four -thiazolidine-2-iminium salts showed growth inhibition against .

Crystal structure of ethyl 2-(4-chlorophenyl)-3-cyclopentyl-4-oxo-1-propyl-imidazolidine-5-carboxylate.

The title compound, C20H27ClN2O3, was obtained via an original synthesis method. The central heterocyclic ring adopts a shallow envelope conformation, with the N atom bearing the cyclo-pentane ring as the flap [deviation from the other atoms = 0.442 (2) Å].