Access to Hindered Homopropargylic Tertiary Alcohols via Nucleophilic Addition of Chiral Copper Species Forming an All-Carbon Quaternary Center.

We report the nucleophilic addition of chiral organocopper species derived from 1,3-enynes to carbonyl compounds, including ketones and aldehydes, providing efficient access to homopropargyl diols bearing an adjacent chiral all-carbon quaternary center. The reaction proceeds through γ-selective addition of an axially chiral allenylcopper intermediate, producing encumbered alcohol products via axial-to-point chirality transfer. A broad range of ketones was accommodated under mild conditions, affording alcohols bearing vicinal quaternary centers in good yields and enantioselectivities up to >99:1.