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

Cis-2-iminothiazolidines and cis-thiazolidine-2-iminium tetrafluoroborates were successfully produced from trans-N-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 cis-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 cis-thiazolidine-2-iminium salts showed growth inhibition against Bacillus cereus.