Non-heme iron catalysis in C C, C–H, and CH2 oxidation reactions. Oxidative transformations on terpenoids catalyzed by Fe(bpmen)(OTf)2
作者:David Clemente-Tejeda、Alejandro López-Moreno、Francisco A. Bermejo
DOI:10.1016/j.tet.2013.02.013
日期:2013.4
The oxidation of terpene olefins with hydrogen peroxide in the presence of the non-hemo catalyst 5a afforded mixtures of epoxides whose composition was dependent upon the oxidation protocol used in each case. With terpenoid enones, the mixtures obtained evolved from clean epoxidation of α-ionone 23 to the clean allylic oxidation of damascone 28 due to the progressive deactivation of the electron density
Bimetallic Radical Redox-Relay Catalysis for the Isomerization of Epoxides to Allylic Alcohols
作者:Ke-Yin Ye、Terry MCallum、Song Lin
DOI:10.1021/jacs.9b04993
日期:2019.6.19
exceptionally high reactivity. Strategically, achieving synthetically useful transformations mediated by organic radicals requires both efficient initiation and selective termination events. Here, we report a new catalytic strategy, namely, bimetallic radical redox-relay, in the regio- and stereoselectiverearrangement of epoxides to allylic alcohols. This approach exploits the rich redox chemistry of Ti
有机自由基通常是具有异常高反应性的短寿命中间体。从战略上讲,实现由有机自由基介导的合成有用的转化需要有效的引发和选择性终止事件。在这里,我们报告了一种新的催化策略,即双金属自由基氧化还原继电器,用于环氧化物向烯丙醇的区域和立体选择性重排。这种方法利用了 Ti 和 Co 配合物的丰富氧化还原化学,并将还原性环氧化物开环(引发)与氢原子转移(终止)相结合。至关重要的是,在影响关键的成键和断裂事件时,Ti 和 Co 催化剂彼此进行质子转移/电子转移以实现周转,从而构成真正协同的双催化系统。
Transition-Metal-Catalyzed Allylic Substitution and Titanocene-Catalyzed Epoxypolyene Cyclization as a Powerful Tool for the Preparation of Terpenoids
作者:Andreas Gansäuer、José Justicia、Antonio Rosales、Dennis Worgull、Björn Rinker、Juan Manuel Cuerva、Juan Enrique Oltra
DOI:10.1002/ejoc.200600389
日期:2006.9
active substances are composed of sesquiterpene units linked to aromatic structures, especially substituted phenols. Here, we describe an efficient synthetic approach to this class of natural product from commercially available substances in a short sequence. The key transformations involve allylicsubstitution reactions using a palla
Rhodium acetate-catalyzed aerobic Mukaiyama epoxidation of alkenes
作者:Dmitry Shabashov、Michael P. Doyle
DOI:10.1016/j.tet.2013.09.062
日期:2013.11
Mukaiyama epoxidation of alkenes under oxygen catalyzed by rhodium acetate with isobutyraldehyde as the reducing agent is as or more effective than previously reported procedures. A variety of alkenes, including terpenes and cholesterol derivatives, were oxidized. And high regioselectivity for mono-epoxidation was observed with neryl, geranyl, and linalyl acetates. (C) 2013 Elsevier Ltd. All rights reserved.