title: Efficient boron-copper additions to aryl-substituted alkenes promoted by NHC-based catalysts. enantioselective Cu-catalyzed hydroboration reactions.
abstract: A Cu-catalyzed method for efficient boron-copper addition processes involving acyclic and cyclic disubstituted aryl olefins are reported. Reactions are promoted with 0.5-5 mol % of a readily available N-heterocyclic carbene (NHC) complex; the presence of MeOH promotes in situ protonation of the C-Cu bond and leads to efficient catalyst turnover, constituting a net Cu-catalyzed hydroboration process. Reactions proceed in >98:<2 site selectivity and furnish secondary organoborane isomers that complement those obtained through reactions of boron-hydride reagents or by Rh- or Ir-catalyzed hydroborations (benzylic secondary C-B bonds). Initial observations regarding processes catalyzed by chiral NHC complexes, delivering products in up to 99:1 enantiomeric ratio, are disclosed.
authors.affiliation: Department of Chemistry, Merkert Chemistry Center, Boston College, Chestnut Hill, Massachusetts 02467, USA.
authors.forename: Yunmi
authors.initials: Y
authors.lastname: Lee
authors.forename: Amir H
authors.initials: AH
authors.lastname: Hoveyda
mesh_terms: D000475:Alkenes / Q000737:chemistry*; D001895:Boron / Q000737:chemistry*; D001897:Boronic Acids / Q000138:chemical synthesis* / Q000737:chemistry; D002384:Catalysis; D003300:Copper / Q000737:chemistry*; D006571:Heterocyclic Compounds / Q000737:chemistry*; D008697:Methane / Q000031:analogs & derivatives* / Q000737:chemistry; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: D000475:Alkenes; D001897:Boronic Acids; D006571:Heterocyclic Compounds; D009942:Organometallic Compounds; C030011:carbene; D003300:Copper; D001895:Boron; D008697:Methane