Synthesis of Multifunctional Organoboron Compounds by Copper-Catalyzed Enantioselective Reactions

Abstract

Chapter 1. We have developed a catalytic method for enantio- and SN2’-selective allylic substitution of commercially available diborylmethane to trisubstituted allylic phosphates (pin = pinacolato). The transformations are catalyzed by NHC–Cu complexes (NHC = N-heterocyclic carbene). Products bearing quaternary stereogenic carbon centers are obtained in up to 86% yield (after oxidation), >98:2 SN2’/SN2 selectivity and 95:5 enantiomeric ratio (e.r.). Chapter 2. We have developed a facile multicomponent catalytic process that begins with a chemo- and site-selective copper–hydride addition to allenyl-B(pin) followed by enantioselective conjugate addition of the resulting allylcopper intermediate to α,β-unsaturated malonate, generating products that contain a stereogenic center and an easily functionalizable alkenyl-B(pin) group in up to 84% yield, >98:2 E/Z selectivity and 96:4 enantiomeric ratio. The transformations are catalyzed by chiral Cu complexes derived from commercially available bisphosphines and CuCl.