Construction of Chiral Quaternary Carbon through Morita-Baylis-Hillman Reaction: An Enantioselective Approach to 3-Substituted 3-Hydroxyoxindole Derivatives
作者:Xiao-Yang Guan、Yin Wei、Min Shi
DOI:10.1002/chem.201002240
日期:2010.12.10
A new enantioselectiveapproach to obtain a tetrasubstituted chiral center at the C3 position of oxindoles via a catalytic asymmetric Morita–Baylis–Hillmanreaction has been demonstrated. This reaction provides 3‐substituted 3‐hydroxy‐2‐oxindoles in good to excellent yields and ee values, which could be facilely transformed to pharmaceutically more interesting compounds.
Nucleophilic β-Carbon Activation of Propionic Acid as a 3-Carbon Synthon by Carbene Organocatalysis
作者:Zhichao Jin、Ke Jiang、Zhenqian Fu、Jaume Torres、Pengcheng Zheng、Song Yang、Bao-An Song、Yonggui Robin Chi
DOI:10.1002/chem.201501481
日期:2015.6.22
Direct β‐carbonactivation of propionic acid (C2H5CO2H) by carbene organocatalysis has been developed. This activation affords the smallest azolium homoenolate intermediate (without any substituent) as a 3‐carbon nucleophile for enantioselective reactions. Propionic acid is an excellent raw material because it is cheap, stable, and safe. This approach provides a much better solution to azolium homoenolate
已经开发了通过卡宾有机催化作用对丙酸(C 2 H 5 CO 2 H)进行直接β-碳活化。这种活化提供了最小的均氮唑鎓中间体(无任何取代基),作为对映选择性反应的3碳亲核试剂。丙酸是便宜,稳定和安全的原料,因此是一种极好的原料。这种方法比以前建立的丙烯醛(没有任何取代基的烯醛)使用昂贵,不稳定且有毒的方法提供了更好的解决方案,用于合成均氮唑鎓。
β-Functionalization of Carboxylic Anhydrides with β-Alkyl Substituents through Carbene Organocatalysis
作者:Zhichao Jin、Shaojin Chen、Yuhuang Wang、Pengcheng Zheng、Song Yang、Yonggui Robin Chi
DOI:10.1002/anie.201408604
日期:2014.12.1
The first NHC‐catalyzed functionalization of carboxylicanhydrides is described. In this reaction, the β carbon behaves as a nucleophilic carbon and undergoes asymmetric reactions with electrophiles. Anhydrides with challenging β‐alkyl substituents work effectively.
Chemoselective Intermolecular Cross-Benzoin Reaction of Aliphatic Aldehydes and Isatins via N-Heterocyclic Carbene Catalysis
作者:Haojie Ji、Jianfeng Xu、Hongjun Ren
DOI:10.1055/s-0037-1612250
日期:2019.5
cross-benzoin reaction of aliphaticaldehydes with isatins is developed, affording biologically important 3-substituted 3-hydroxyoxindoles (on gram scale) in moderate to good yields (46–90%). The employment of a morpholinone-derived pentafluorophenyl-substituted triazolium salt as the electron-deficient NHC pre-catalyst is essential to make the reaction go through the cross-benzoin reaction pathway rather
Carbene‐Catalyzed Enantioselective Aldol Reaction: Post‐Aldol Stereochemistry Control and Formation of Quaternary Stereogenic Centers
作者:Xing Yang、Pankaj Kumar Majhi、Huifang Chai、Bin Liu、Jun Sun、Ting Liu、Yonggui Liu、Liejin Zhou、Jun Xu、Jiawei Liu、Dongdong Wang、Yanli Zhao、Zhichao Jin、Yonggui Robin Chi
DOI:10.1002/anie.202008369
日期:2021.1.4
The dominated approaches for asymmetric aldol reactions have primarily focused on the aldol carbon–carbon bond‐forming events. Here we postulate and develop a new catalytic strategy that seeks to modulate the reaction thermodynamics and control the product enantioselectivities via post‐aldol processes. Specifically, an NHC catalyst is used to activate a masked enolate substrate (vinyl carbonate) to