Organocatalytic Asymmetric Alkylation of Aldehydes by SN1-Type Reaction of Alcohols
作者:Pier Giorgio Cozzi、Fides Benfatti、Luca Zoli
DOI:10.1002/anie.200805423
日期:2009.2.2
Work‐alcoholic! The elusive enantioselective catalytic α‐alkylation of aldehydes, a widely sought transformation, was brought to execution by the use of alcohols capable of forming stabilized carbocations (see scheme, TFA=trifluoroacetic acid).
Pyrrolidine-derived functionalizedchiralionicliquids (FCILs) have been found to catalyzeasymmetric S N 1 α-alkylations of ketones and aldehydes with up to 99 % yield, >99:1 dr and 87 % ee. The FCIL catalysts enable S N 1 α-alkylations of cyclicketones, particularly of 3- and 4-substituted cyclohexanones with excellent diastereoselectivity and good enantioselectivity, featuring unprecedented desymmetrization
已发现吡咯烷衍生的官能化手性离子液体 (FCIL) 可催化酮和醛的不对称 SN 1 α-烷基化反应,产率高达 99%,>99:1 dr 和 87% ee。FCIL 催化剂使环酮,特别是 3-和 4-取代环己酮的 SN 1 α-烷基化具有优异的非对映选择性和良好的对映选择性,为这些类型的不对称反应提供了前所未有的去对称化和动力学拆分过程。介绍了这项研究的全部细节以及提议的烯胺过渡态。
Organocatalytic Stereoselective α-Alkylation of Aldehydes with Stable Carbocations
作者:Fides Benfatti、Elena Benedetto、Pier Giorgio Cozzi
DOI:10.1002/asia.201000160
日期:2010.9.3
stereoselective alkylation of aldehydes is carried out with the four stable carbocations 1, 2, 3, 4 in the presence of a catalytic amount (20 mol%) of MacMillan imidazolidinones 5, 6. In all reactions, lutidine was used as a base. The alkylation reactions are investigated at different temperatures with linear and branched aldehydes. In the case of carbocation tropyliumfluoroborate, an interesting
Silyl‐Modified Analogues of 2‐Tritylpyrrolidine: Synthesis and Applications in Asymmetric Organocatalysis
作者:Jonathan O. Bauer、Julian Stiller、Eugenia Marqués‐López、Katja Strohfeldt、Mathias Christmann、Carsten Strohmann
DOI:10.1002/chem.201002166
日期:2010.11.8
Silicon‐based organocatalysts: In an effort to study the effects of substituting carbon by silicon within the catalyst backbone, we developed an efficient synthesis of (S)‐2‐triphenylsilylpyrrolidine [(S)‐2]. The evaluation of (S)‐2 against its carbon analogue (S)‐1 in two organocatalytic reactions is complemented by computational studies.
Electricity-driven enantioselective cross-dehydrogenative coupling of two C(sp3)-H bonds enabled by organocatalysis
作者:Yuemin Chen、Yunqi Wu、Guoao Wang、Feihu Cui、Haitao Tang、Yingming Pan
DOI:10.1016/j.cclet.2023.109445
日期:2024.9
without additional oxidants for the cross-dehydrogenativecouplingreaction (CDC) of two C(sp)-H bonds is reported. A series of aldehydes including natural products and various substrates containing C(sp)-H bonds including xanthenes, acridines, cycloheptatrienes and even diarylmethane have been shown to undergo asymmetric CDC to afford a series of carbon-carbon bondcoupling products with up to 94% yield