Enantioselective alkynylation of aromatic aldehydes catalyzed by readily available chiral amino alcohol-based ligands

The asymmetric alkynylation reaction catalyzed by amino alcohol derived ligands (1R,2S)-3 or (1S,2R)-4 with dimethylzinc provides a simple and practical method to make chiral propargylic alcohols, and it is complementary to the asymmetric reduction methods. In the presence of 10 mol% (1R,2S)-3 or (1S,2R)4, a variety of aromatic aldehydes were converted to the corresponding chiral propargylic alcohols with very good enantioselectivities and yields. This one-pot asymmetric reaction is carried out under mild reaction conditions. Neither strong base nor transmetallation is required. It is an efficient reaction, greatly accelerated by the added chiral ligand. Preliminary mechanistic and NMR studies have also been carried out.