system was mainly suitable for aromatic allylicalcohols, and the yield was excellent as determined via gram-scale synthesis. The main product was double bond near the side of a more electron-rich aryl group when allylicalcohols featuring different substituents at the 1 and 3 positions were used as the substrates. Deuterium-labelled experiments clearly demonstrated that the hydrogen source was the
实现了由布朗斯台德酸催化的高活性烯丙醇的直接无金属脱氧,避免了繁琐的反应步骤并消除了金属污染。通过考察一系列布朗斯台德酸、醇、反应温度等,以10 mol% TsOH·H 2 O为催化剂,2当量时,收率高达94%。以对甲基苯甲醇为还原剂,在 80 °C 反应 2 h。该体系主要适用于芳香族烯丙醇,收率良好克级合成。当使用在 1 位和 3 位具有不同取代基的烯丙醇作为底物时,主要产物是靠近更富电子的芳基一侧的双键。氘标记实验清楚地表明氢源是对甲基苯甲醇的亚甲基,其他对照实验表明存在两种醚中间体。有趣的是,烯丙基苄基醚的原位氢转移是一个关键过程,但动力学同位素效应研究 ( k H / k D= 1.28)表明C-H键断裂不是速率决定步骤。提出了一种可能的机制,涉及碳正离子、醚中间体和氢转移。
Palladium-catalyzed cross-couplings of allylic carbonates with triarylbismuths as multi-coupling atom-efficient organometallic nucleophiles
作者:Maddali L.N. Rao、Debasis Banerjee、Somnath Giri
DOI:10.1016/j.jorganchem.2010.03.010
日期:2010.5
Allylic carbonates were efficiently cross-coupled with triarylbismuthsunderpalladiumcatalysis. Using the optimized protocol, arylations of various allylic carbonates were carried out with triarylbismuths to afford high yields of 1,3-disubstituted propenes in regio- and chemo-selective manner. Triarylbismuths were employed as multi-coupling atom-efficient organometallic nucleophiles in sub-stoichiometric
Heck-type Benzylation of Olefins with Benzyl Trifluoroacetates
作者:Hirohisa Narahashi、Akio Yamamoto、Isao Shimizu
DOI:10.1246/cl.2004.348
日期:2004.3
A new synthetic method for 1-aryl-2-alkenes from 1-olefins by benzylation treating with benzyl trifluoroacetates using palladium-catalyst is developed on the basis of oxidative addition of benzyl carboxylates to Pd(0) complexes to give benzyl(carboxylato)palladium(II) complexes with cleavage of benzyl–oxygen bond.
Synthesis of benzylpalladium complexes through C–O bond cleavage of benzylic carboxylates: Development of a novel palladium-catalyzed benzylation of olefins
作者:Hirohisa Narahashi、Isao Shimizu、Akio Yamamoto
DOI:10.1016/j.jorganchem.2007.10.051
日期:2008.1
tertiary phosphines to give benzylpalladium(II) carboxylate complexes with cleavage of the benzyl-oxygen bond. The benzylpalladium complexes having the trifluoroacetato ligand react with olefins such as ethyl acrylate to give olefin benzylation products. On the basis of these studies a novel palladium-catalyzed benzylation of olefins was developed without using organic halides as the starting materials