Catalytic N-formylation for synthesis of 6-substituted-2-benzothiazolylimino-5-piperazinyl-4-thiazolidinone antimicrobial agents

Abstract

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-(benzo[d]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.