Organic reactions in aqueous media catalyzed by nickel

Abstract

The expansion of catalytic methods is a focus of contemporary interest due to the adverse effects of the manufacturing process of fine chemicals, pharmaceuticals, and materials on the environment. In this context, introducing sustainability via earth-abundant metal catalysis in aqueous media, particularly nickel-catalyzed reactions, not only minimizes the waste footprint of the process but also offers cost-effective synthetic routes. Although nickel offers variable oxidation states and multifaceted catalytic cycles, performing Ni-catalysis in aqueous media is fundamentally challenging owing to the relative instability of nickel complexes in water, resulting in catalytic deactivation and diminished selectivity profile of the catalysts. In this context, this review addresses the recent advances in nickel-catalyzed organic reactions in an aqueous medium. Herein, we discuss various commonly exercised reactions, viz. C–C and C–X (X = N, O, S) cross-coupling, C–H functionalization/annulation, cycloaddition, hydrogenation, oxidation, aldehydic/ketone alkylation, functional group removal, polymerization, etc., in aqueous media in the presence of nickel catalyst. The review further highlights the mechanistic course of reactions, preparation of recyclable Ni-catalysts, recycling and reusability study, and their applications in aqueous organic reactions.