Recent Progress in Transition-Metal-Catalyzed Reductive Cross-Coupling Reactions Using Diboron Reagents as Reductants

Transition-metal-catalyzed reductive cross-coupling reactions have been developed as one of the important tools for constructing C–C bonds. These reactions involve the direct coupling of two distinct electrophiles promoted by transition metals and reductants. Notably, these methods offer advantages over conventional cross-coupling reactions because they circumvent the need for air- and moisture-sensitive organometallic reagents while being simple to operate and exhibiting good compatibility with various functional groups. In recent years, diboron reagents have gained prominence as reductants for reductive cross-coupling reactions alongside traditional metal reductants, such as Zn, Mn, and Mg. This Review aims to provide an insightful overview of nickel/copper/iron-catalyzed reductive coupling reactions using diboron reagents as reductants and illustrate their possible reaction mechanisms.