Enantioselective Radical Cyclization for Construction of 5-Membered Ring Structures by Metalloradical C–H Alkylation
作者:Yong Wang、Xin Wen、Xin Cui、X. Peter Zhang
DOI:10.1021/jacs.8b01662
日期:2018.4.11
use of unsaturated substrates. Guided by the concept of metalloradicalcatalysis, a different mode of radical cyclization that can employ saturated C-H substrates is demonstrated through the development of a Co(II)-based system for catalytic activation of aliphatic diazo compounds for enantioselective radical alkylation of various C(sp3)-H bonds. It allows for efficient construction of chiral pyrrolidines
自由基环化代表了构建环状结构的强大策略。传统的自由基环化以自由基加成为关键步骤,需要使用不饱和底物。在金属自由基催化概念的指导下,通过开发基于Co(II)的系统,展示了一种可以使用饱和CH底物的不同自由基环化模式,该系统用于催化活化脂肪族重氮化合物,以实现各种C(sp3)的对映选择性自由基烷基化)-H键。它可以有效构建手性吡咯烷和其他有价值的五元环状化合物。这种自由基环化的替代策略提供了一种新的逆合成范例,通过 CH 和 C=O 元素的结合形成 CC 键,从容易获得的开链醛制备五元环状分子。
Manganese catalyzed reductive amination of aldehydes using hydrogen as a reductant
作者:Duo Wei、Antoine Bruneau-Voisine、Dmitry A. Valyaev、Noël Lugan、Jean-Baptiste Sortais
DOI:10.1039/c8cc01787e
日期:——
A one-pot two-step procedure was developed for the alkylation of aminesvia reductive amination of aldehydes using molecular dihydrogen as a reductant in the presence of a manganese pyridinyl-phosphine complex as a pre-catalyst. After the initial condensation step, the reduction of imines formed in situ is performed under mild conditions (50–100 °C) with 2 mol% of catalyst and 5 mol% of tBuOK under
Cyclometallated imine complexes with oxygen-functionalised side-chains: Effect of the nature of the functional group, chain length and charge on coordination of the oxygen
作者:David L. Davies、Omar Al-Duaij、John Fawcett、Kuldip Singh
DOI:10.1016/j.jorganchem.2007.12.012
日期:2008.3
undergo cyclometallation with [Pd(OAc)2]3 (in some cases the dimeric products 2 were isolated) and subsequently react with lithium chloride to give chloride complexes, which are dimeric 3a–c, or monomeric for the C3H6OH-functionalised complexes 4d,e which have a C,N,O tridentate imine. The chloride complexes subsequently react with triphenylphosphine, and in some cases pyridine, to give mononuclear complexes
衍生自苯甲醛或3,4-二甲氧基苯甲醛和醚或醇官能化胺H 2 NR(R = C 2 H 4 OMe,C 3 H 6 OMe,C 2 H 4 OH,C 3 H 6的亚胺1a – e OH,)全部与[Pd(OAc)2 ] 3进行环金属化反应(在某些情况下,分离出二聚产物2),然后与氯化锂反应生成氯化物络合物,该络合物为二聚体3a – c或对C 3而言是单体高6具有C,N,O三齿亚胺的OH-官能化的络合物4d,e。氯化物络合物随后与三苯基膦反应,在某些情况下与吡啶反应,分别与双齿C,N亚胺反应生成单核络合物5和6。用银盐处理5会导致阳离子,系链的长度(C2或C3)和供体的性质(醚或醇)以及抗衡离子均会影响氧的配位情况。