Solvent free Montmorillonite K-10 Clay catalyzed synthesis and Structure elucidation of pyrazoloimidazole-2-thione Derivatives

The pharmaceutical industry faces challenges such as the use of toxic solvents, excessive use of energy, waste generation and the implementation of conventional procedures that do not adhere to green chemistry principles. In the present study, we report the prompt mineral (Montmorillonite K-10 clay) triggered cyclo-condensation of chloroacetic acid with arylthiourea subsequently followed by Knoevenagel condensation with aromatic aldehyde in combination with sodium acetate without solvents microwave irradiation results in 3-aryl-5-benzylideno-2-thiohydantoins 4(a-l). The substances 4 (a-l) with hydrazine hydrate in glacial acetic acid offered the intermediate acetyl hydrazone of 4(a-l) which on cyclo-isomerization under reaction conditions gave 1,8-diaryl-4,8-dihydro-1-acetylpyrazolo[3,4-c] imidazole-2-thiones 5 (a-l).