Cascade reactions initiated by radical addition of tetrahydrofuran to β-bromonitrostyrenes
作者:Xin Ge、Kim Le Mai Hoang、Min Li Leow、Xue-Wei Liu
DOI:10.1039/c4ra08357a
日期:——
Silver(i) catalyzed addition of THF radical to β-bromonitrostyrenes under mild basic condition in the presence of air has been developed.
在温和碱性条件下,银(i)催化的四氢呋喃自由基加成到β-溴硝基苯乙烯中,并在空气存在下发展起来的。
Silver-Catalyzed C-H
Insertion Reactions with Donor-Acceptor Diazoacetates
作者:Carl Lovely、H. Dias、Jaime Flores、Xiaofeng Meng
DOI:10.1055/s-0028-1087377
日期:——
In this paper we describe the first examples of carbene transfer with donor-acceptor diazoacetates and the silver tris(pyrazolyl)borate complex HB[3,5-(CF3)2Pz]3}Ag(THF). These reactions generally proceed in good yields and exhibit improved selectivities compared to simple diazoacetates.
Asymmetric Catalysis via Cyclic, Aliphatic Oxocarbenium Ions
作者:Sunggi Lee、Philip S. J. Kaib、Benjamin List
DOI:10.1021/jacs.6b11993
日期:2017.2.15
A direct enantioselectivesynthesis of substituted oxygen heterocycles from lactol acetates and enolsilanes has been realized using a highly reactive and confined imidodiphosphorimidate (IDPi) catalyst. Various chiral oxygen heterocycles, including tetrahydrofurans, tetrahydropyrans, oxepanes, chromans, and dihydrobenzofurans, were obtained in excellent enantioselectivities by reacting the corresponding
C–H Insertion Catalyzed by Tetratolylporphyrinato Methyliridium via a Metal–Carbene Intermediate
作者:Bernie J. Anding、Jakoah Brgoch、Gordon J. Miller、L. Keith Woo
DOI:10.1021/om3005433
日期:2012.8.13
Kinetic studies for C–Hinsertion reactions using different substrates showed substantial differences in the rate of MPDA consumption, suggesting that carbene transfer is rate-limiting. Furthermore, primary kinetic isotopeeffects of 3.7 ± 0.3 and 2.7 ± 0.4 were measured using toluene and cyclohexane, respectively. These data are consistent with a mechanism that involves direct C–Hinsertion rather than a
四甲苯基卟啉对甲基铱(Ir(TTP)CH 3)催化不同底物与重氮试剂之间的CH插入反应。重氮唑试剂2-苯基重氮乙酸甲酯(MPDA)与含有富电子的C–H键的底物之间的反应获得了最高的收率。使用1 H NMR和UV / vis吸收光谱,鉴定出一种中间金属卟啉配合物为金属-卡宾配合物Ir(TTP)(═C[Ph] CO 2 CH 3)(CH 3)(4)。在场4通过与时间相关的DFT(6-31G(d,p)/ SBKJC基本集,PBE0功能)对吸收光谱进行计算建模来进一步支持。使用不同底物进行C–H插入反应的动力学研究表明MPDA消耗速率存在显着差异,这表明卡宾转移是限速的。此外,分别使用甲苯和环己烷测得的一次动力学同位素效应为3.7±0.3和2.7±0.4。这些数据与涉及直接C–H插入而不是根本的反弹途径的机制是一致的。
Enantioselective C–H carbene insertions with homogeneous and immobilized copper complexes
作者:José M. Fraile、Pilar López-Ram-de-Viu、José A. Mayoral、Marta Roldán、Jorge Santafé-Valero
DOI:10.1039/c1ob05499f
日期:——
The efficiency of chiral bis(oxazoline)- and azabis(oxazoline)-copper complexes in the enantioselective carbene insertion into CâH bonds of cyclic ethers in homogeneous phase strongly depends on the structure of the substrate. The immobilization on laponite clay by electrostatic interactions not only allows the recovery and reuse of the heterogeneous catalysts, but in some cases also improves enantioselectivity and overall chemoselectivity, making possible reactions that do not take place or lead to low yields in solution, even with the commonly used Rh2[S-DOSP]4 catalyst.