Asymmetric Organocatalytic Direct Aldol Reactions of Ketones with α-Keto Acids and Their Application to the Synthesis of 2-Hydroxy-γ-butyrolactones
作者:Xiao-Ying Xu、Zhuo Tang、Yan-Zhao Wang、Shi-Wei Luo、Lin-Feng Cun、Liu-Zhu Gong
DOI:10.1021/jo701868t
日期:2007.12.1
of organocatalysts for the asymmetric direct aldolreactions of ketones with α-keto acids were designed on the basis of molecular recognition and prepared from proline and aminopyridines. The organic molecule 8e, derived from proline and 6-methyl-2-amino pyridine, was the best catalyst, affording excellent enantioselectivities (up to 98% ee) for the direct aldolreactions of acetone or 2-butanone with
Asymmetric Direct Aldol Reaction of α-Keto Esters and Acetone Catalyzed by Bifunctional Organocatalysts
作者:Fei Wang、Yan Xiong、Xiaohua Liu、Xiaoming Feng
DOI:10.1002/adsc.200700285
日期:2007.12.10
A type of C2-symmetrical bisprolinamide has been developed for the asymmetricaldolreaction between acetone and α-ketoesters, which furnishes the chiral tertiary alcohols in high yields (up to 99 %) with high enantioselectivities (up to 94 % ee). Aliphatic, heteroaromatic and aromatic α-ketoesters including those with electron-donating or electron-withdrawing group substituents were found to be
Design of Highly Enantioselective Organocatalysts Based on Molecular Recognition
作者:Zhuo Tang、Lin-Feng Cun、Xin Cui、Ai-Qiao Mi、Yao-Zhong Jiang、Liu-Zhu Gong
DOI:10.1021/ol0529391
日期:2006.3.1
Various organocatalysts have been designed based on molecular recognition to catalyze the asymmetric direct aldol reaction of ketones with aryl and alkyl alpha-keto acids, affording beta-hydroxyl carboxylic acids with a tertiary stereogenic center with excellent enantioselectivities of up to 98% ee. A linear effect was observed for the reaction, demonstrating a single molecule of the catalyst involved in the catalysis.
In Situ Formed Bifunctional Primary Amine-Imine Catalyst for Asymmetric Aldol Reactions of α-Keto Esters
In prime condition: The hydrolysis of a chiral diimine precursor can be carried out by a Brønsted acid to form an in situprimaryamine–imine intermediate as a bifunctionalprimary aminocatalyst, which promoted direct asymmetricaldolreactions between α‐keto esters and ketones in high yields (up to 88 %) and with excellent enantioselectivities (see scheme; R1, R2, R4=alkyl; R3=aryl).
在最佳条件下:手性二亚胺前体的水解可通过布朗斯台德酸进行,形成原位伯胺-亚胺中间体,作为双官能伯氨基催化剂,从而促进α-酮酯与酮之间的直接不对称醛醇缩合反应。产率(高达88%)并且具有优异的对映选择性(参见方案; R 1,R 2,R 4=烷基; R 3=芳基)。