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
Contrasting steric effects of the ketones and aldehydes in the reactions of the diisopinocampheyl enolborinates of methyl ketones with aldehydes
作者:P.Veeraraghavan Ramachandran、Wei-chu Xu、Herbert C. Brown
DOI:10.1016/0040-4039(96)00969-0
日期:1996.7
representative series of aldehydes, both of differing steric requirements provides aldols whose enantiomeric purities depend on the steric requirements of both the ketones and the aldehydes. This study has shown that increasing the steric requirements of the R group in the ketones has a pernicious effect on the ee, while increasing the steric requirements of the R group in the aldehydes exerts a beneficial
The Role of β-Bulky Substituents in Aldol Reactions of Boron Enolates of Methylketones with Aldehydes: Experimental and Theoretical Studies by DFT Analysis
作者:Luiz C. Dias、Emílio C. de Lucca、Marco A. B. Ferreira、Danilo C. Garcia、Cláudio F. Tormena
DOI:10.1021/jo2023119
日期:2012.2.17
5-stereoselectivities of aldolreactions of boronenolates generated from β-alkoxy methylketones with aldehydes. Excellent levels of 1,5-syn stereoinduction were obtained when the β-protecting group is a silicon ether. This remarkable selectivity is attributed to the volume of the β-bulky substituent of the corresponding boronenolate. We have investigated a stereochemical model using DFT analysis to
Chiral 1,3-oxazolidines are readily prepared from methyl ketones and chiral norephedrine. Formation of stannous azaenolates from the oxazolidines and reaction with aldehydes followed by removal of the chiral auxiliary lead to the aldol products in high level of enantiomeric purity.
Thiazolidine-based organocatalysts for a highly enantioselective direct aldol reaction
作者:Raoní S. Rambo、Paulo H. Schneider
DOI:10.1016/j.tetasy.2010.07.028
日期:2010.9
exhibits the highest catalytic performance working in an aqueous medium. It catalyzed the directcatalyticasymmetric intermolecular aldolreaction between unmodifiedketones and an aldehyde with excellent stereocontrol and furnished the corresponding aldol products in up to 99% ee. Compound 3a also showed excellent asymmetriccatalytic activity in the asymmetric Michael reaction (up to 99% ee).