Copper(I)-Catalyzed Regioselective Propargylic Substitution Involving Si–B Bond Activation
作者:Devendra J. Vyas、Chinmoy K. Hazra、Martin Oestreich
DOI:10.1021/ol201811d
日期:2011.8.19
The silicon nucleophile generated by copper(I)-catalyzed Si-B bond activation allows several gamma-selective propargylic substitutions. The regioselectivity (gamma:alpha ratio) Is strongly dependent on the propargylic leaving group. Chloride Is superior to oxygen leaving groups in linear substrates (gamma:alpha > 99:1), and it is only the phosphate group that also shows promising regiocontrol (gamma:alpha = 90:10). That leaving group produces superb gamma-selectivity (gamma:alpha > 99:1) in alpha-branched propargylic systems, and enantioenriched substrates react with excellent central-to-axial chirality transfer.
Copper(I)-Catalyzed Regio- and Chemoselective Single and Double Addition of Nucleophilic Silicon to Propargylic Chlorides and Phosphates
作者:Chinmoy K. Hazra、Martin Oestreich
DOI:10.1021/ol301827t
日期:2012.8.3
Copper(I)-catalyzed propargylic substitution of linear precursors with (Me2PhSi)2Zn predominantly yields the γ isomer independent of the propargylic leaving group. The thus formed allenylic silane reacts regioselectively with another equivalent of (Me2PhSi)2Zn, yielding a bifunctional building block with allylic and vinylic silicon groups. The reaction rates of both steps are well-balanced for chloride