The versatile roles of ammonium salt catalysts in enantioselective reduction and alkylation of α,β-unsaturated aldehydes: iminium catalysis, enamine catalysis and acid catalysis
A novel strategy for highly efficient utilization of chiral ammonium salt catalysts has been described in this paper. Three kinds of catalytic functions including iminium catalysis, enaminecatalysis, and acid catalysis of chiral ammonium salt catalysts, have been achieved in the enantioselective reduction and alkylation reaction of alpha,beta-unsaturated aldehydes with alcohols.
Catalytic stereoselective benzylic C–H functionalizations by oxidative C–H activation and organocatalysis
作者:Fides Benfatti、Montse Guiteras Capdevila、Luca Zoli、Elena Benedetto、Pier Giorgio Cozzi
DOI:10.1039/b910185c
日期:——
An organocatalytic stereoselective α-alkylation reaction of aldehydes based on CâH activation is presented.
提出了一种基于C–H活化的有机催化立体选择性α-烷基化反应,用于醛类化合物。
Electro-Organocatalysis: Enantioselective α-Alkylation of Aldehydes
作者:Xuan-Huong Ho、Sun-il Mho、Hyuk Kang、Hye-Young Jang
DOI:10.1002/ejoc.201000453
日期:——
The asymmetric organocatalyzed α-alkylation of aldehydes via a cationicradical enamine intermediate was performed under environmentally benign electro-oxidation conditions without the use of chemical oxidants. To promote the desired α-alkylationreaction of aldehydes, various aldehydes with xanthene or cycloheptatriene groups were exposed to electro-organocatalytic conditions to afford optically active
An organocatalytic enantioselective intermolecular oxidative dehydrogenative α-alkylation of aldehydes via benzylic C–H bond activation has been developed. The asymmetric reaction is smoothly fulfilled by using simple and green molecular oxygen as the oxidant. Two hydrogen dissociations make this transformation more environmentally benign because of high atom efficiency.
Highly Enantioselective Intermolecular Alkylation of Aldehydes with Alcohols by Cooperative Catalysis of Diarylprolinol Silyl Ether with Brønsted Acid
作者:Jian Xiao、Kai Zhao、Teck-Peng Loh
DOI:10.1002/asia.201100692
日期:2011.11.4
Two cooperative systems: I/2,3,4‐trihydroxybenzoic acid and I/TfOH effect highlyenantioselective intermolecular α‐alkylation of aldehydes. These systems afford functionalized aldehydes in high yields, and with excellent ee and de values with broad substrate scope (see scheme; R1=alkyl, R2,R3=aryl, or R2=ferrocenyl, R3=phenyl, or R2=indolyl, R3=phenyl).