Highly Diastereofacial <i>Anti</i>-Aldol Reaction: Practical Synthesis of Optically Active <i>anti</i>-2-Alkyl-3-Hydroxycarboxylic Acid Ester Units
作者:Michio Kurosu、Miguel Lorca
DOI:10.1021/jo001293h
日期:2001.2.1
variety of esters derived from commercially available norephedrine were used in diastereoselective anti-aldol reactions. The aldolreaction of designed 2-(N-2-methylbenzyl-N-2,4,6-trimethylbenzyl)amino-1-phenylpropanol esters 4a-d with aldehydes furnished anti-2-alkyl-3-hydroxycarboxylic acid esters in excellent diastereomeric ratios (>98:2) when LDA-Cp2ZrCl2 (0.3 equiv) was used for enolization, followed
Asymmetric cross- and self-aldol reactions of aldehydes in water with a polystyrene-supported triazolylproline organocatalyst
作者:Patricia Llanes、Sonia Sayalero、Carles Rodríguez-Escrich、Miquel A. Pericàs
DOI:10.1039/c6gc00792a
日期:——
A polystyrene-immobilized triazolylproline has been prepared by a bottom-up approach involving co-polymerization with full regiocontrol. The resulting PS resin swells in water and has been applied to the enantioselective cross-aldol...
The reduction of α-alkyl-β-hydroxy ketones is highly syn-selective if carried out in THF on their Ti-alcoholate complexes with LiBH4 or L-Selectride® or N-selectride® depending on the bulkiness of the group bound to the carbonyl group.
Attainment of syn-selectivity for boron-mediated asymmetric aldol reactions of carboxylic esters
作者:Ji-Feng Liu、Atsushi Abiko、Zhonghua Pei、Dana C Buske、Satoru Masamune
DOI:10.1016/s0040-4039(98)00123-3
日期:1998.4
reagent for syn-selective aldolreactions has been developed based on the recent finding that the stereochemistry of the boron-mediatedaldolreaction of a carboxylic ester is controlled by the bulkiness of the alcohol moiety of the ester, by the proper choice of reagents, and by the enolization conditions. This readily available, inexpensive reagent has been utilized in studies directed towards the synthesis
Highly stereoselective radical addition to 3-hydroxy-1-(methylthio)-1-(p-tolylsulfonyl)-1-alkenes and its application to the preparation of optically active compounds
Efficient1,2-asymmetricinduction was realized in the addition of a 1-hydroxyalkyl radical (R2C-OH) to 3-hydroxy-1-(methylthio)-1-(p-tolylsulfonyl)-1-alkenes and their acetates (1): Irradiation of 1 and benzophenone in an alcohol (R2CHOH) gave an adduct (2) with a high syn selectivity. Optically active 1 is easily obtainable by means of Lipase PS-catalyzed transesterification and, therefore, the present