Design and Synthesis of C2-Symmetric N-Heterocyclic Carbene Precursors and Metal Carbenoids
摘要:
Chiral, C-2-symmetric imidazolium and imidazolinium ions, as well as the corresponding copper- or silver-bound carbenoids, have been prepared. Structural study of these compounds by X-ray crystallography reveals a chiral pocket that surrounds the putative carbene site or the metal carbene bond, at carbon 2, in three of the four ligands prepared. Preliminary investigation into the application of these complexes has shown one of them to be highly enantioselective in the hydrosilylation of acetophenone.
Copper-Catalyzed Enantioselective Markovnikov Protoboration of α-Olefins Enabled by a Buttressed N-Heterocyclic Carbene Ligand
作者:Yuan Cai、Xin-Tuo Yang、Shuo-Qing Zhang、Feng Li、Yu-Qing Li、Lin-Xin Ruan、Xin Hong、Shi-Liang Shi
DOI:10.1002/anie.201711229
日期:2018.1.26
Reported is a highly enantioselective copper‐catalyzed Markovnikov protoboration of unactivatedterminalalkenes. A variety of simple and abundant feedstock α‐olefins bearing a diverse array of functional groups and heterocyclic substituents can be used as substrates, and the reaction proceeds under mild reaction conditions at ambient temperature to provide expedient access to enantioenriched alkylboronic
Acid-Catalyzed <i>ortho</i>-Alkylation of Anilines with Styrenes: An Improved Route to Chiral Anilines with Bulky Substituents
作者:Anna E. Cherian、Gregory J. Domski、Jeffrey M. Rose、Emil B. Lobkovsky、Geoffrey W. Coates
DOI:10.1021/ol051916j
日期:2005.11.1
[reaction: see text] Reaction of para-substituted anilines with styrene derivatives at elevated temperatures, when catalyzed by CF3SO3H, results in highly chemoselective ortho-alkylation of the aniline. When R = H, dialkylation can be achieved by varying the ratio of styrene to aniline. Several different substituted anilines and styrenes were examined, and good yields (42-87%) were obtained, except
A Chiral Naphthyridine Diimine Ligand Enables Nickel‐Catalyzed Asymmetric Alkylidenecyclopropanations
作者:Elena Braconi、Nicolai Cramer
DOI:10.1002/anie.202006082
日期:2020.9.14
A novel class of chiral naphthyridine diimine ligands (NDI*) readily accessible from C2‐symmetric 2,6‐di‐(1‐arylethyl)anilines is described. The utility of these ligands, particularly one with fluorinated aryl side arms, is demonstrated by a reductive Ni‐catalyzed enantioselective alkylidene transfer reaction from 1,1‐dichloroalkenes to olefins. This transformation provides direct access to a broad