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Keywords:

  • asymmetric alkynylation;
  • asymmetric catalysis;
  • copper;
  • enantioselectivity;
  • α-imino ester;
  • ligand-to-metal ratio

Abstract

The first catalytic asymmetric addition of arylacetylenes to α-imino esters was carried out using chiral copper(I) complexes as catalysts under mild reaction conditions, providing the corresponding alkynylation products in good yields with 67–74 % ee values. Profound effects of the ligand-to-metal ratio and additives on the stereofacial selection were observed. Both enantiomers of a given product can be obtained with almost identical enantiomeric excess using the same chiral ligand by adjusting the ligand-to-metal ratio.