Heck Reactions of α- or β-Substituted Enol Ethers with Aryl Bromides Catalysed by a Tetraphosphane/Palladium Complex – Direct Access to Acetophenone or 1-Arylpropanone Derivatives
作者:Ahmed Battace、Marie Feuerstein、Mhamed Lemhadri、Touriya Zair、Henri Doucet、Maurice Santelli
DOI:10.1002/ejoc.200700152
日期:2007.7
α-arylation of these enol ethers was observed in all cases, but mixtures of (Z) and (E) isomers were generally obtained, which in many cases yielded a single ketone product after acid treatment. The stereoselectivity of this reaction depends on steric and electronic factors, and better stereoselectivities in favour of (Z) isomers were observed with electron-rich or sterically congested aryl bromides
cis,cis,cis-1,2,3,4-Tetrakis(diphenylphosphanylmethyl)cyclopentane/[PdCl(C3H5)]2 有效地催化 α- 和 β- 取代的烯醇醚与芳基溴的 Heck 反应。1-苯基-1-(三甲基甲硅烷氧基)乙烯的芳基化直接导致2-芳基-1-苯基乙酮。在富电子、缺电子或空间拥挤的芳基溴化物中观察到类似的反应速率。与苄基异丙烯基醚的Heck反应得到异构体的混合物。然而,该混合物在水解后选择性地产生1-芳基丙酮。使用 β-甲氧基苯乙烯、3-乙氧基丙烯腈或 3-甲氧基丙烯酸甲酯,在所有情况下都观察到这些烯醇醚的区域选择性 α-芳基化,但通常会得到 (Z) 和 (E) 异构体的混合物,这在许多情况下产生了酸处理后的单一酮产品。该反应的立体选择性取决于空间和电子因素,并且在富电子或空间拥挤的芳基溴化物中观察到有利于 (Z) 异构体的更好的立体选