Multielectron Redox Afforded by a Pincer Ligand Promoting Kumada Cross-Coupling Reactions

The redox-active nature of a pincer has been exploited to conduct C-C cross-coupling reactions under mild conditions. A nickel complex with a NNN pincer was dimeric in the solid state, and the structure displayed a Ni2 N2 diamond core. In the dimeric structure, both ligand backbones house an electron, in the iminosemiquinonate form, to keep the metal's oxidation state at +2. In the presence of an aryl Grignard reagent, only 3 mol % loading the nickel complex generates a Kumada cross-coupled product in good yield from a wide variety of aryl-X (X= I, Br, Cl) substrates. That the ligand-based radical remains responsible for promoting such a coupling reaction following a radical pathway is suggested by TEMPO quenching. Furthermore, a radical-clock experiment along with tracing product distribution unambiguously supported the radical's involvement through the catalytic cycle. A series of thorough mechanistic probation, including computational DFT analysis, disclosed the cooperative action of both redox-active pincer ligand and the metal centre to drive the reaction.

A decennary update on applications of metal nanoparticles (MNPs) in the synthesis of nitrogen- and oxygen-containing heterocyclic scaffolds

Heterocycles have been found to be of much importance as several nitrogen- and oxygen-containing heterocycle compounds exist amongst the various USFDA-approved drugs. Because of the advancement of nanotechnology, nanocatalysis has found abundant applications in the synthesis of heterocyclic compounds. Numerous nanoparticles (NPs) have been utilized for several organic transformations, which led us to make dedicated efforts for the complete coverage of applications of metal nanoparticles (MNPs) in the synthesis of heterocyclic scaffolds reported from 2010 to 2019. Our emphasize during the coverage of catalyzed reactions of the various MNPs such as Ag, Au, Co, Cu, Fe, Ni, Pd, Pt, Rh, Ru, Si, Ti, and Zn has not only been on nanoparticles catalyzed synthetic transformations for the synthesis of heterocyclic scaffolds, but also provide an inherent framework for the reader to select a suitable catalytic system of interest for the synthesis of desired heterocyclic scaffold.