Ionic Liquid-Promoted, Highly Regioselective Heck Arylation of Electron-Rich Olefins by Aryl Halides
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- 作者：Jun Mo ; Lijin Xu ; and Jianliang Xiao
- 刊名：Journal of the American Chemical Society
- 出版年：2005
- 出版时间：January 19, 2005
- 年：2005
- 卷：127
- 期：2
- 页码：751 - 760
- 全文大小：160K
- 年卷期：v.127,no.2(January 19, 2005)
- ISSN：1520-5126
文摘
Palladium-catalyzed regioselective Heck arylation of the electron-rich olefins, vinyl ethers 1a-d, enamides 1e-g, and allyltrimethylsilane 1h, has been accomplished in imidazolium ionic liquids with awide range of aryl bromides and iodides instead of the commonly used, but commercially unavailable andexpensive, aryl triflates. The reaction proceeded with high efficiency and remarkable regioselectivity withoutthe need for costly or toxic halide scavengers, leading exclusively to substitution by aryl groups of diverseelectronic and steric properties at the olefinic carbon 
to the heteroatom of 1a-g and 
to the heteroatomof 1h. In contrast, the arylation reaction in molecular solvents led to mixtures of regioisomers under similarconditions. Several lines of evidence point to the unique regiocontrol stemming from the ionic environmentprovided by the ionic liquid that alters the reaction pathway. The chemistry provides a simple, effectivemethod for preparing branched, arylated olefins and contributes to the extension of Heck reaction to awider range of substrates.
to the heteroatom of 1a-g and to the heteroatomof 1h. In contrast, the arylation reaction in molecular solvents led to mixtures of regioisomers under similarconditions. Several lines of evidence point to the unique regiocontrol stemming from the ionic environmentprovided by the ionic liquid that alters the reaction pathway. The chemistry provides a simple, effectivemethod for preparing branched, arylated olefins and contributes to the extension of Heck reaction to awider range of substrates.