Synthesis of biologically active spiro oxindole through multicomponent reaction and it’s physico-chemical studies

Indole-2,3-dione has been utilized in many multicomponent reactions that produce complex spiro compounds with readily available starting materials and considered as an importantbuilding block in organic synthesis. Spiro compounds in which two cyclic rings are fused at a common carbon atom are promising interesting skeletal systems in drug discovery due to their unique conformational features, structural complexity and rigidity. Here we have synthesized a spiro-oxindole which has been synthesized from indole-2,3-dione, dimedone and 2-aminobenzimidazole using nickel-zinc ferrite silicate nano composite as catalyst, and characterization of synthesized spiro-oxindole compound were carried. Computationalstudies of the synthesized compound were performed using DFT method at the CAM-B3LYP/6–311++G (d, p) level. Geometry optimization, FMO studies, vibrational and NBO analysis reveals the molecular structure, electronic transitions and intramolecular charge delocalization of the Spiro oxindole.Molecular docking studies of the synthesized compound was evaluated for their antimicrobial activities against three bacteria viz., Staphylococcus aureus, E-Coli, Klebsiella species andfungus viz., Aspergillus Niger. The spiro-oxindole compound showed very good invitro DPPH scavenging antioxidantproperty.