Pharmaceutical Chemistry

Biography

Biography: Sundaram Singh

Abstract

An increase in regulatory limitations on the use, manufacture and disposal of perilous organic solvents has focused attention on the development of non-hazardous alternatives such as solvent-less synthesis, multicomponent reactions and reusable heterogeneous catalysts for the sustainable development of chemical enterprise. These organic reactions possess many advantages over traditional reactions in organic solvents. For example, solvent-less, multicomponent reactions with reusable heterogeneous catalysts reduce the consumption of environmentally hazardous solvents and minimize the formation of other waste. The reactions occur under mild conditions and usually require easier workup procedures and simpler equipment.

Nano zirconia (ZrO₂) have been widely investigated in the past decades due to their multiple potential applications. The crystal phase of ZrO₂ (monoclinic and tetragonal) strongly influences the catalyst activities and selectivities.

A highly efficient method for the synthesis of substituted imidazoles from a multicomponent reaction of isatin derivatives with ammonium acetate and aromatic aldehydes under solvent free conditions has been established. The reaction is supposed to proceed via nano ZrO₂-catalyzed C=O bond activation followed by the formation of diamine intermediate and its condensation with ZrO₂ activated isatin derivatives. Because of the simple and readily available starting materials, easy operation and high bioactivity of imidazoles, this strategy can be broadly applied to medical chemistry. The recyclability of the nano ZrO₂ catalyst is another emphasis of proposed methodology.
Scheme 1: Synthesis of imidazole derivatives 4a-r via multicomponent reaction of isatin derivatives 1a-f with ammonium acetate 2 and substituted aromatic aldehydes 3a-f.