1,1'-Binaphthyl Ligands with Bulky 3,3'-Tertiaryalkyl Substituents for the Asymmetric Alkyne Addition to Aromatic Aldehydes.

The BINOL ligand (R)-2 that contains bulky 3,3'-tertiaryalkyl groups shows improved catalytic properties than the previously reported 3,3'-substituted BINOL ligands in the asymmetric alkyne addition to aromatic aldehydes. It can catalyze the phenylacetylene addition to aromatic aldehydes with high enantioselectivity (86 - 94% ee) and good yields without using Ti(O(i)Pr)(4) and a Lewis base additive. The catalytic properties of several analogs of (R)-2 in the asymmetric alkyne addition to aldehydes have also been studied. .