Microwave-assisted tandem reactions for the synthesis of 2-hydrazolyl-4-thiazolidinones

A tandem method for the synthesis of 2-hydrazolyl-4-thiazolidinones (5) from commercially available materials in a 3-component reaction has been developed. The reaction connects aldehydes, thiosemicarbazides, and maleic anhydride, effectively assisted by microwave irradiation. The synthesis of a new type of compound, 2-hydrazolyl-5,5-diphenyl-4-thiazolidinone (7), obtained by treatment of thiosemicarbazone with benzil in basic media is also reported. HOMO/LUMO energies, orbital coefficients, and charge distribution were used to explain the proposed reaction mechanism.

Microwave-assisted tandem synthesis of 2-hydrazolyl-4- thiazolidinones 5 is described starting from commercially available aldehydes, maleic acid, and thiosemicarbazide. The novel 5,5-diphenyl-4-thiazolidinone 7 was obtained by reaction of thiosemicarbazone with benzil in basic media through a benzilic rearrangement.