Versatile Homoallylic Boronates by Chemo-, SN 2'-, Diastereo- and Enantioselective Catalytic Sequence of Cu-H Addition to Vinyl-B(pin)/Allylic Substitution

Angew Chem Int Ed Engl. 2017 Jan 16;56(3):821-826. doi: 10.1002/anie.201611444. Epub 2016 Dec 20.

Abstract

A highly chemo-, diastereo- and enantioselective catalytic method that efficiently combines a silyl hydride, vinyl-B(pin) (pin=pinacolato) and (E)-1,2-disubstituted allylic phosphates is introduced. Reactions, best promoted by a Cu-based complex with a chiral sulfonate-containing N-heterocyclic carbene, are broadly applicable. Aryl-, heteroaryl-, alkenyl-, alkynyl- and alkyl-substituted allylic phosphates may thus be converted to the corresponding homoallylic boronates and then alcohols (after C-B bond oxidation) in 46-91 % yield and in up to >98 % SN 2':SN 2 ratio, 96:4 diastereomeric ratio and 98:2 enantiomeric ratio. The reasons why an NHC-Cu catalyst is uniquely effective (vs. the corresponding phosphine systems) and the basis for different trends in stereoselectivity are provided with the aid of DFT calculations.

Keywords: boron; copper; enantioselective catalysis; enantioselective synthesis; multicomponent reactions.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Alcohols / chemical synthesis*
  • Alcohols / chemistry
  • Allyl Compounds / chemistry*
  • Boronic Acids / chemical synthesis*
  • Boronic Acids / chemistry
  • Catalysis
  • Copper / chemistry*
  • Heterocyclic Compounds / chemistry
  • Hydrogen / chemistry*
  • Methane / analogs & derivatives
  • Methane / chemistry
  • Molecular Structure
  • Quantum Theory
  • Stereoisomerism

Substances

  • Alcohols
  • Allyl Compounds
  • Boronic Acids
  • Heterocyclic Compounds
  • carbene
  • Copper
  • Hydrogen
  • Methane