General and Mild Ni<sup>0</sup>-Catalyzed α-Arylation of Ketones Using Aryl Chlorides
作者:José A. Fernández-Salas、Enrico Marelli、David B. Cordes、Alexandra M. Z. Slawin、Steven P. Nolan
DOI:10.1002/chem.201406457
日期:2015.3.2
A general methodology for the α‐arylation of ketones using a nickel catalyst has been developed. The new well‐defined [Ni(IPr*)(cin)Cl] (1 c) pre‐catalyst showed great efficiency for this transformation, allowing the coupling of a wide range of ketones, including acetophenone derivatives, with various functionalised arylchlorides. This cinnamyl‐based Ni–N‐heterocyclic carbene (NHC) complex has demonstrated
已经开发了使用镍催化剂对酮进行α-芳基化的一般方法。定义明确的新型[Ni(IPr *)(cin)Cl](1 c)预催化剂显示出极高的转化效率,使各种酮(包括苯乙酮衍生物)与各种官能化的芳基氯化物偶合。这种基于肉桂基的Ni-N-杂环卡宾(NHC)配合物表现出与以前报道的NHC-Ni催化剂不同的行为。初步的机理研究表明,Ni 0 / Ni II催化循环起作用。
Environmentally benign contemporary Friedel–Crafts acylation of 1-halo-2-methoxynaphthalenes and its related compounds under conventional and nonconventional conditions
作者:K. Rajendar Reddy、K.C. Rajanna、K. Uppalaiah
DOI:10.1016/j.tetlet.2013.04.075
日期:2013.6
Environmentally benign simple and practical method has been developed in cationic micellar media for the selective acylations of 1-halo-2-methoxynaphthalenes, 2-methoxynaphthalene, anisole, 2-methoxypyridine, and 2-methoxypyrimidine. Developed protocols afforded good to excellent yields of products in the presence of a catalytic amount of cationic micelles (CTAB and CTAC) under conventional and nonconventional
with electron-rich or sterically congested arylbromides. Better yields were obtained for this reaction with electron-rich or sterically congested arylbromides than with electron-poor arylbromides. This observation suggests that with these β-substituted enol ethers the rate-limiting step of the catalytic cycle is not the oxidative addition of the arylbromide to the palladium complex.
顺式,顺式,顺式-1,2,3,4-四(二苯基膦甲基)环戊烷/ [PdCl(C 3 H 5)] 2有效催化β-取代的烯醇醚与芳基溴的Heck反应。在所有情况下,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,均能观察到这些烯醇醚的区域选择性α-芳基化作用,并且通常获得Z和E异构体的混合物,在许多情况下,经分离后生成单一的酮产物酸处理。该反应的立体选择性取决于空间和电子因素,有利于Z的更好的立体选择性在富含电子或空间上富集的芳基溴化物中观察到异构体。用富电子或空间拥挤的芳基溴化物比用贫电子的芳基溴化物能获得更好的收率。该观察结果表明,对于这些β-取代的烯醇醚,催化循环的限速步骤不是将芳基溴化物氧化加成到钯配合物中。
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
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