α‑Boryl Organometallic Reagents in Catalytic Asymmetric Synthesis

Recent years have witnessed an increase in the popularity of α-boryl organometallic reagents as versatile nucleophiles in asymmetric synthesis. These compounds have been adopted in chemo- and stereoselective coupling reactions with a number of different electrophiles. The resulting enantioenriched boronic esters can be applied in stereospecific carbon–carbon or carbon–heteroatom bond construction reactions, enabling a two-step strategy for the construction of complex structures with high efficiency and functional group compatibility. For these reasons, tremendous effort has been devoted to the preparation of enantiomerically enriched α-boryl organometallic reagents and to the development of stereoselective reactions of related racemic or prochiral materials. In this review, we describe enantio- or diastereoselective reactions that involve α-boryl organometallic reagents as starting materials or products and showcase their synthetic utility.