Chiral Bicyclic NHC/Cu Complexes for Catalytic Asymmetric Borylation of α,β-Unsaturated Esters
作者:Yuya Miwa、Takumi Kamimura、Kiyoaki Sato、Daichi Shishido、Kazuhiro Yoshida
DOI:10.1021/acs.joc.9b02096
日期:2019.11.1
The potential of using chiral bicyclic NHC ligands that exhibit modularity was investigated in the Cu-catalyzed asymmetric borylation reaction of α,β-unsaturatedesters. After screening for ligands and optimization of the reaction conditions, the corresponding products were afforded with good enantioselectivities (up to 85% ee).
Configuration Sampling With Five‐Membered Atropisomeric
<i>P</i>
,
<i>N</i>
‐Ligands
作者:Gaurav Dahiya、Mukesh Pappoppula、Aaron Aponick
DOI:10.1002/anie.202102642
日期:2021.9
systematic variation of atropisomeric C1-symmetric P,Nligands to incrementally change the position of the groups within the chiral pocket without modifying their steric parameters. More specifically, the effects of systematic modification of the nitrogen heterocycle in atropisomeric C1-symmetric stack ligands have been investigated in this study. The versatility and applicability of this approach
在这里,我们报告了一种对阻转异构体 C 1对称 P,N 配体进行系统变异的策略,以逐步改变手性袋中基团的位置,而不修改它们的空间参数。更具体地,本研究已经研究了阻转异构C 1对称堆叠配体中氮杂环的系统修饰的影响。这种方法的多功能性和适用性已在机械上不同的催化对映选择性转化中得到证明,从而鉴定了用于高度对映选择性合成有机硼烷的 P,N-配体。
Well-Defined Chiral Copper NHC Complex in the Asymmetric Conjugated β-Borylation and One-Pot Metathesis-Asymmetric β-Borylation Reactions
Highly stereoselective conjugate β‐borylation, using a new chiral NHC‐based copper catalyst, has been achieved. The chiral NHC copper complex was prepared in gram scale and showed high enantioselectivity and activity (up to 10 000 turnovers at 100 ppm of catalyst loading). This method was employed in the synthesis of a chiral β‐borylated ester from simple unconjugated alkenes though an unprecedented
Facile Synthesis of Chiral Benzimidazolium Salts and the Application in Asymmetric Catalytic Borylation
作者:Zhihua Sun、Jie Zhou、Xiaohui Liu
DOI:10.3987/com-16-13434
日期:——
A synthetic method towards chiral benzimidazolium salts is developed. The stereocenter is introduced by direct aromatic substitution of 2-fluoronitrobenzene with optically pure amines. After nitro group reduction, selective arylation of the primary amine is achieved via copper catalyzed Chan-Lam coupling reaction. Finally, cyclization of the diamine with HC(OMe)(3) afforded the desired chiral benzimidazolium salts. In situ generated benzimidazole carbenes show potential application for asymmetric catalytic borylation of alpha,beta-unsaturated esters, providing up to 85% ee value with a catalyst loading of only 0.5 mol%.