A simple green synthesis of (Z)-5-arylmethylene-4-thioxothiazolidines and thiopyrano2,3-dthiazolidine-2-thiones in PEG-400 under catalyst-free conditions

摘要

An improved Knoevenagel condensation of various aromatic aldehydes with thiazolidine-2,4-dithione and with 4-thioxothiazolidin-4-one can be achieved at room temperature in polyethylene glycol-400 without catalyst to afford (Z)-5-arylmethylene-4-thioxothiazolidine derivatives 3a-3o. Also, the 4+2 cyloaddition reaction of 3a-3g with N-phenylmaleimide 4 gave the cycloadducts 5a-5g under the same reactions conditions. The structure of all the newly synthesized compounds was established on the basis of the elemental analysis and spectral data. This process is a simple, efficient, economical, and environmentally benign compared to classical reactions.