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