Aluminum-Catalyzed Enantio- and Diastereoselective Carbonyl Addition of Propargylsilanes. A New Approach to Enantioenriched Vinyl Epoxides
摘要:
A new pathway involving a Lewis acid-catalyzed carbonyl addition reaction of propargylsilanes and its subsequent development into a general enantio- and diastereoselective process are described. Aliphatic propargylsilanes with both saturated and unsaturated sidechains were effective nucleophiles affording highly functionalized chiral vinyl epoxides in good enantioselectivities (85-94% ee), excellent diastereoselectivities (> 99:1 E:Z; > 99:1 anti:syn) and in moderate to good yields (49-97%).
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