Highly Enantioselective Synthesis of γ‐Hydroxy‐α,β‐acetylenic Esters by Asymmetric Alkyne Addition to Aldehydes

Alkynoates are added to aromatic and α,β-unsaturated aldehydes in the synthesis of the title compounds in optically active form. This highly enantioselective and useful method is carried out under mild reaction conditions and employs the readily available chiral 1,1′-bi-2-naphthol (binol) ligand and the metal reagents Et2Zn and [Ti(OiPr)4] (see scheme; HMPA=hexamethylphosphoramide).