Copper(I)-catalyzed regioselective propargylic substitution involving Si-B bond activation.

The silicon nucleophile generated by copper(I)-catalyzed Si-B bond activation allows several γ-selective propargylic substitutions. The regioselectivity (γ:α ratio) is strongly dependent on the propargylic leaving group. Chloride is superior to oxygen leaving groups in linear substrates (γ:α > 99:1), and it is only the phosphate group that also shows promising regiocontrol (γ:α = 90:10). That leaving group produces superb γ-selectivity (γ:α > 99:1) in α-branched propargylic systems, and enantioenriched substrates react with excellent central-to-axial chirality transfer.