Enantioselective, Rhodium-Catalyzed 1,4-Addition of Organoboron Reagents to Electron-Deficient Alkenes

The rhodium-catalyzed 1,4-addition of organoboron reagents to electron-deficient alkenes is a versatile method for the enantioselective construction of carbon–carbon bonds. The scope of these reactions is broad, and alkenes activated by adjacent carbonyls, imines, nitriles, phosphonyl groups, nitro groups, sulfonyl groups, C=N-containing aromatic heterocycles, electron-deficient arenes, or boryl groups are effective substrates. Regarding the pronucleophilic component, aryl-, heteroaryl-, and alkenylboron reagents have been successfully employed. In addition, numerous chiral ligands have been developed which impart high enantioselectivities onto these reactions. Importantly, these reactions usually proceed under mild, experimentally convenient conditions, with no requirement for precautions to exclude air or moisture. This chapter presents the scope and limitations of this process, along with a discussion of the current understanding of the mechanistic and stereochemical features. Incorporation of this process into domino reactions is discussed, as is its application in the synthesis of biologically active molecules. The literature is covered up until the end of 2013. Keywords: alkene; asymmetric catalysis; chiral ligand; enantioselectivity; organoboron reagent; rhodium