Improved Conditions for the Proline-Catalyzed Aldol Reaction of Acetone with Aliphatic Aldehydes
作者:Benjamin List、Alberto Martínez、Kristina Zumbansen、Arno Döhring、Manuel van Gemmeren
DOI:10.1055/s-0033-1340919
日期:——
The proline-catalyzed asymmetric aldol reaction between aliphatic aldehydes and acetone has, to date, remained underdeveloped. Challenges in controlling this reaction include avoiding undesired side reactions such as aldol condensation and self-aldolization. In recent years we have developed optimized conditions, which enable high yields and good to excellent enantioselectivities, and which are presented
Metal-Free Catalytic Boration at the β-Position of α,β-Unsaturated Compounds: A Challenging Asymmetric Induction
作者:Amadeu Bonet、Henrik Gulyás、Elena Fernández
DOI:10.1002/anie.201001198
日期:——
Enantiomerically enriched secondary organoboronates containing β‐carbonyl functional groups have been prepared using an unprecedented organocatalytic system (see scheme). The use of chiral tertiary phosphorus compounds induced ee values of up to 95 % in the absence of transition metals.
Proline-Catalyzed Asymmetric Aldol Reactions between Ketones and α-Unsubstituted Aldehydes
作者:Benjamin List、Peter Pojarliev、Chris Castello
DOI:10.1021/ol006976y
日期:2001.2.1
[reaction: see text] With this communication we extend the methodology of proline-catalyzed direct asymmetric aldol reactions to include alpha-unsubstituted aldehydes as acceptors. This important aldehyde class gives the corresponding aldols in 22-77% yield and up to 95% ee when the reactions are performed in pure acetone or in ketone/chloroform mixtures. On the basis of these results we have developed
An enantioselective synthesis of (+)-(S)-[n]-gingerols via the l-proline-catalyzed aldol reaction
作者:Shichao Ma、Shilei Zhang、Wenhu Duan、Wei Wang
DOI:10.1016/j.bmcl.2009.03.081
日期:2009.7
An enantioselective approach to (+)-(S)-[n]-gingerols (1a–c) has been developed. The requisite stereogenic centers of target molecules are facilely constructed by the proline-catalyzed cross-aldol reaction from readily available achiral starting materials.
对(+)-(S)-[ n ]-姜酚(1a – c)的对映选择性方法已经开发出来。靶分子的必需立体异构中心是由脯氨酸催化的交叉羟醛缩合反应轻松地从容易获得的非手性原料中构建的。
Efficient asymmetric catalysis of chiral organoaluminum complex for enantioselective ene reactions of aldehydes
Chiral organoaluminum complex 1 efficiently catalyzed the asymmetric hetero-ene reaction of commercially available 2-methoxypropene (2) with aldehydes under mild conditions to give the corresponding β-hydroxymethyl ketones 3 in good to excellent chemical yields with high enantiomeric excesses. The asymmetriccatalysis of 1 was further applied to the carbonyl addition of methallylsilanes, where exclusive