An expedient synthesis of C3-arylidene-oxindole derivatives using calcite nanoflowers as an efficient heterogeneous catalyst

Abstract

α-β unsaturated heterocyclic compounds such as C3-arylidene-oxindoles, with five-member rings containing nitrogen, have an important role in the realm of medicine. This study aims to synthesize the C3-arylindene-oxindoles derivative compounds using calcite nanoflowers (CaCO3 NFs) as a heterogeneous catalyst for the first time. These CaCO3 NFs prepared by the thermal decomposition method, which is an active and reusable catalyst for stereospecific Knoevenagel condensation reaction between 2-oxindole and aromatic aldehyde under different solvent conditions like water, ethyl alcohol, and 50% aqueous ethyl alcohol. This catalytic method is employed with a wide range of aromatic aldehydes to produce high yields of C3-arylidene-oxindoles (93-99%), with stereo-specifically E-isomers (100%) for 50% alcohol and alcohol as a solvent.