Recent advances in transition metal-catalyzed organic transformations using hemilabile P,P=O ligands

Abstract

Bisphosphine monoxides (BPMOs) represent a distinctive class of hemilabile bidentate ligands featuring a trivalent phosphine as a soft coordination site combined with a hard coordination site in the form of P(V)=O, hence referred to as P,P=O ligands. Despite their potential benefits, including their ability to regulated a variety of elementary reactions essential in organic reaction enabled by transition metal, such as ligand exchange, isomerization, oxidative addition, migratory insertion, and reductive elimination, P,P=O ligands have not garnered significant attention relative to other hemilabile ligands and bidentate phosphine ligands in the past decades. This limited recognition is due to challenges associated with their synthesis methods and their inconspicuous presence within high-valent transition-metal/bidentate phosphine ligand catalytic systems under basic or oxygen-containing conditions. The incorporation of P,P=O ligands in transition-metal catalyzed organic reactions offers a pathway characterized by low activation energy for a diverse range of reactions. Herein, this article provides a comprehensive review of the utilization of BPMO ligands in transition metal-catalyzed organic transformations from about 2004 to present, encompassing addition reactions, alkene functionalization reactions, coupling reactions, [4+2] cycloadditions, C-H functionalizations, and other transformations.