Poly vinyl Sulfonic acid supported on nano rice husk silica: an efficient catalyst for the one-pot synthesis of 1H-indazolo[2,1-b]-Phthalazinetrione

Phthalazine derivatives are an important class of heterocyclic compounds due to their wide range of pharmaceutical and biological activities.1 Phthalazine derivatives was reported to possess anticonvulsant; antifungal, anticancer, and vasorelaxant activities.2 Therefore, considerable effort has been devoted toward finding an efficient synthesis of phthalazine derivatives. In this research, sodium silicate was produced from the rice husk by acidic titration and burning process and then converted to nano silica under acidic conditions. The polyvinyl sulfonic acid was easily prepared by the reaction of polyvinyl alcohol and chloro sulfonic acid and supported on the extracted nano silica by simple grinding. The catalytic activity of this solid acid nanocomposite, NanoSilica/PVSA, was probed through the One-Pot synthesis of 1H-indazolo[2,1-b]-Phthalazinetrione via three-component couplings of phthalhydrazide, aromatic aldehydes, and dimidone. In this reactions NanoSilica/PVSA shows a highly catalytic nature, easy to handle procedure, easy workup, recycle exploitation, good to excellent isolated yields and the elimination of solvent that is a relatively environmentally important.