Catalytic <Emphasis Type="Italic">N</Emphasis>-formylation for synthesis of 6-substituted-2-benzothiazolylimino-5-piperazinyl-4-thiazolidinone antimicrobial agents

A new class of piperazine-based 2-benzothiazolylimino-4-thiazolidinones has been efficiently prepared via highly accelerated N-formylation of N-isopropylpiperazine by the use of a mild heterogeneous catalyst, sulfated tungstate. Heterocyclization of N-(benzod]thiazol-2-yl)-2-chloroacetamides (3a–j) by use of NH₄SCN in ethanol under reflux efficiently furnished the intermediates 2-benzothiazolyliminothiazolidin-4-ones (4a–j). These were treated with 4-isopropylpiperazine-1-carbaldehyde (2) to prepare the final products 5a–j. The structures of the new derivatives were confirmed by elemental analysis and use of spectroscopic data (FTIR and ¹H NMR). Their pharmacological potential as promising antimicrobial agents was determined in vitro against bacteria and a fungus; the lowest minimum inhibitory concentrations (MIC) observed were in the range 4–8 µg/mL.