Catalytic, Enantioselective, Copper–Boryl Additions to Alkenes

Abstract

Enantiomerically enriched organoboron compounds are of considerable utility in organic synthesis. Unlike other organometallic reagents (e.g., RM, M = Li, Al, Mg, or Zn), boron‐containing hydrocarbons possess a number of desirable properties that include air, moisture, and configurational stability in addition to ease of preparation and exceptional functional group tolerance. Multicomponent, CB bond forming reactions, catalyzed by readily accessible, copper‐based complexes, have recently emerged as an attractive option for efficient, chemo‐, regio‐, diastereo‐ and enantioselective generation of multifunctional organoboron compounds. These processes typically begin with the addition of a copper–boryl complex to an alkenyl site, generating a copper–alkyl intermediate that then reacts with an electrophile. The focus of this chapter will be these transformations. A brief analysis of the key mechanistic nuances that impact the observed selectivity will be followed by an overview of the scope and limitations of the various strategies and their applications to the synthesis of bioactive molecules.

Copper-Catalyzed Borylative Difunctionalization of π-Systems

“…This review presents a comprehensive examination of the electrophiles reported in copper-catalyzed borylative difunctionalizations. − The focus is on the intricacies and challenges associated with stereocontrol. The review is divided on the basis of the type of electrophilic termination and will not cover formal hydroboration methods resulting from protodemetalation.…”

Sulfonate N‐Heterocyclic Carbene–Copper Complexes: Uniquely Effective Catalysts for Enantioselective Synthesis of C−C, C−B, C−H, and C−Si Bonds

“…Different Cu-based catalysts have been developed for net enantioselective addition of aB -H unit across an alkene (Scheme 62 b,c). [124] These transformations complement or offer an alternative to the earlier processes,p romoted by aRh-or Ir-based complex (Scheme 62 a).…”

Beyond Carbon: Enantioselective and Enantiospecific Reactions with Catalytically Generated Boryl- and Silylcopper Intermediates

“…Alkenes are more delicate substrates. The regio­selectivity is an additional complication influenced by the catalytic system and the nature of the substituents on the double bond . For terminal alkenes, the sterically favored anti -Markovnikov-type products are predominantly formed, passing through the branched alkyl­copper intermediates V / VI with a stereo­genic carbon atom for R 1 ≠ R 2 (Scheme c). − The subsequent protonation occurs with retention of the configuration.…”