Enantioselective Alkynylation of Trifluoromethyl Ketones Catalyzed by Cation-Binding Salen Nickel Complexes

Angew Chem Int Ed Engl. 2020 Jan 7;59(2):775-779. doi: 10.1002/anie.201913057. Epub 2019 Dec 2.

Abstract

Cation-binding salen nickel catalysts were developed for the enantioselective alkynylation of trifluoromethyl ketones in high yield (up to 99 %) and high enantioselectivity (up to 97 % ee). The reaction proceeds with substoichiometric quantities of base (10-20 mol % KOt-Bu) and open to air. In the case of trifluoromethyl vinyl ketones, excellent chemo-selectivity was observed, generating 1,2-addition products exclusively over 1,4-addition products. UV-vis analysis revealed the pendant oligo-ether group of the catalyst strongly binds to the potassium cation (K+ ) with 1:1 binding stoichiometry (Ka =6.6×105 m-1 ).

Keywords: alkynylation; bifunctional catalysis; nickel; trifluoromethylketones.

Publication types

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

MeSH terms

  • Catalysis
  • Ketones / chemistry*
  • Molecular Structure
  • Nickel / chemistry*
  • Stereoisomerism

Substances

  • Ketones
  • Nickel