BINOL-catalyzed highly enantioselective terminal alkyne additions to aromatic aldehydes

[GRAPHICS] The readily available BINOL ligand in combination with Ti((OPr)-Pr-i)(4) was found to catalyze the highly enantioselective reaction (92-98% ee) of terminal alkynes with aromatic aldehydes that contain a variety of substituents and substitution patterns. After the preparation of the zinc acetylide reagent, the catalytic asymmetric addition to aldehydes proceeded at room temperature with excellent stereocontrol. This simple catalyst system is practical for the asymmetric synthesis of chiral propargylic alcohols.