Alcohols react with arenes in the presence of cationic iron(III) porphyrin catalyst. The reaction involves the formation of the C–C bond via dehydration, which is formal Lewis acid catalyzed Friedel–Craftsreaction.
Calcium-Catalyzed Friedel-Crafts Alkylation at Room Temperature
作者:Meike Niggemann、Matthias J. Meel
DOI:10.1002/anie.200907227
日期:2010.5.10
A novel calcium catalyst was found to efficiently functionalize electron‐rich arenes with secondary and tertiary benzylic, propargylic, and allylic alcohols under very mild reaction conditions. The new catalyst system significantly enlarges the scope of the reaction, which was previously limited except for the few examples with secondary benzylicalcohols.
Supercritical Carbon Dioxide: A Promoter of Carbon-Halogen Bond Heterolysis
作者:Thais Delgado-Abad、Jaime Martínez-Ferrer、Ana Caballero、Andrea Olmos、Rossella Mello、María Elena González-Núñez、Pedro J. Pérez、Gregorio Asensio
DOI:10.1002/anie.201303819
日期:2013.12.9
Amazing reaction medium: Supercritical carbon dioxide, with zero dipole moment, lower dielectric constant than pentane, and non‐hydrogen‐bonding behavior, ionizes carbon–halogen bonds, dissociates the resulting ion pairs, and escapes from capture by the carbocation intermediates at temperatures above 40 °C. These properties allow the observation of carbocation chemistry in the absence of acids.
S<sub>N</sub>1 reactions in supercritical carbon dioxide in the presence of alcohols: the role of preferential solvation
作者:Thais Delgado-Abad、Jaime Martínez-Ferrer、Rafael Acerete、Gregorio Asensio、Rossella Mello、María Elena González-Núñez
DOI:10.1039/c6ob01097k
日期:——
Ethanol (3b) inhibits SN1reactions of alkyl halides 1 in supercritical carbon dioxide (scCO2) and gives no ethers as products. The unexpected behaviour of alcohols 3 in the reaction of alkyl halides 1 with 1,3-dimethoxybenzene (2) in scCO2 under different conditions is rationalised in terms of Brønsted and Lewis acid–base equilibria of reagents, intermediates, additives and products in a singular
乙醇(3b)抑制烷基卤化物1在超临界二氧化碳(sc CO 2)中的S N 1反应,并且不产生醚类产物。酒精3在卤代烃1与1,3-二甲氧基苯(2)在sc CO 2中的不同条件下反应的意外行为,通过Brønsted和Lewis酸碱平衡试剂,中间体,添加剂和产物的合理化得到了合理化。一种具有以下特征的奇异溶剂:(i)二氧化碳的强四极杆和路易斯酸特性,阻碍了S N通过强力溶解基本溶质的2条路径; (ii)二氧化碳的弱路易斯碱特性,阻止其表现为质子吸收体;(iii)sc CO 2的可压缩性质,其在溶剂需求速率确定步骤中增强了优先溶剂化对二氧化碳可利用性的影响。
Graphene-Catalyzed Direct Friedel–Crafts Alkylation Reactions: Mechanism, Selectivity, and Synthetic Utility
Transition-metal-catalyzed alkylation reactions of arenes have become a central transformation in organic synthesis. Herein, we report the first general strategy for alkylation of arenes with styrenes and alcohols catalyzed by carbon-based materials, exploiting the unique property of graphenes to produce valuable diarylalkane products in high yields and excellent regioselectivity. The protocol is characterized
芳烃的过渡金属催化烷基化反应已成为有机合成的核心转化。在此,我们报告了第一个由碳基材料催化的芳烃与苯乙烯和醇类烷基化的一般策略,利用石墨烯的独特性质以高产率和优异的区域选择性生产有价值的二芳基烷烃产品。该协议的特点是广泛的底物范围和出色的官能团耐受性。值得注意的是,该过程构成了石墨烯的第一个普遍应用,以利用锚定在 GO 表面上的极性官能团促进直接 CC 键的形成,从而为使用良性且易于获得的石墨烯材料进行一系列官能团烷基化打开了大门。