C−H Activation of Benzamides Using Biogenically Synthesized Pd@CNTs Catalyst under External Ligand Free Condition: Access to Isoquinolones and A DFT Study of Phytochemicals

Abstract

AbstractEnvironmentally amiable biogenic strategy for in‐situ one‐step synthesis of Pd‐NPs decorated on carbon nanotubes (CNTs) and its synthetic utility for C−H activation of benzamides to access isoquinolones has been reported for the first time. The phytochemicals present in Gliricidia sepium leaves extract was found to be serve as a reducing agent to reduce Pd (II) to Pd (0) and subsequently acts as a stabilizing agent. The formation of Pd@CNTs was confirmed by P‐XRD, FE‐SEM, EDX and ICP‐OES analysis technique with active Pd content 42.82 % w/w. In addition, DFT study of phytochemicals found in Gliricidia sepium leaves extract were conducted. The catalytic activity was showcased for the cost‐effective, step and atom economic synthesis of isoquinolones via C−H and N−H bond activation without the aid of external ligands. A series of isoquinolone derivatives were synthesized in good to excellent yields under air as a sole oxidant. In addition, catalyst recyclability and mechanistic experiments were deliberated. The Pd@CNTs unveiled superior catalytic activity and high durability towards hydrogen evolution reaction in acidic media. The Pd@CNTs attains the current density of 10 mA/cm2 at an over potential of 127 mV with a small Tafel slope of 41 mV/dec.