Iron-Catalyzed Highly Regio- and Stereoselective Conjugate Addition of 2,3-Allenoates with Grignard Reagents
作者:Zhan Lu、Guobi Chai、Shengming Ma
DOI:10.1021/ja075750o
日期:2007.11.28
An efficient highly regio- and stereoselective iron-catalyzed conjugate addition of 2,3-allenoates with primary or secondary alkyl, phenyl, or vinyl Grignardreagents to synthesize multi-substituted β,γ-unsaturated enoates has been reported. The in situ formed magnesium dienolate may readily react with different electrophilic reagents to construct an allylic quaternary carbon at the α-position of the
Controllable Highly Stereoselective Reaction of <i>in situ</i> Generated Magnesium Dienolate Intermediates with Different Electrophiles
作者:Zhan Lu、Guobi Chai、Xiaobing Zhang、Shengming Ma
DOI:10.1021/ol8012815
日期:2008.8.21
In this paper, we have described an efficient controllable stereoselective a-acylation and -allylation reaction of the magnesium dienolate intermediates generated in situ from the Fe(III)-catalyzed reaction between 2,3-allenoates and Grignard reagents with different electrophiles to afford 2-acylated or allylated 3(Z)- or (E)-alkenoates depending on the nature of the electrophiles and reaction conditions. The distinct stereoselectivity may be caused by the isomerization of metallic Z-1,3-dienoate to E-1,3-dienoate via the intermediacy of anti-allylic MgCl and syn-metallic species.