α-amino acid monomer (5) derived from (S)-tryptophan was copolymerized with styrene and divinylbenzene under radical polymerization conditions to give a polymer-supported N-sulfonyl-(S)-tryptophan (6). Treatment of the polymer-supported chiral ligand with 3,5-bis(trifluoromethyl)phenyl boron dichloride afforded a polymeric Lewisacid catalyst (16) effective for asymmetric Mukaiyamaaldolreaction of silyl
Direct Asymmetric Aldol Reaction of Aryl Ketones with Aryl Aldehydes Catalyzed by Chiral BINOL-Derived Zincate Catalyst
作者:Hong Li、Chao-Shan Da、Yu-Hua Xiao、Xiao Li、Ya-Ning Su
DOI:10.1021/jo801182n
日期:2008.9.19
Directasymmetricaldol reaction of aryl ketones with aryl aldehydes catalyzed by chiral metal complex is reported for the first time herein. Two novel semicrown chiral ligands 1a and 1b were synthesized from (S)- and (R)-BINOL, respectively, and then employed to catalyze the directasymmetricaldol addition of aryl ketones to aryl aldehydes. Introduced with 2.0 equiv of diethylzinc, 1b had higher
Direct asymmetric aldol reaction of acetophenones with aromatic aldehydes catalyzed by chiral Al/Zn heterobimetallic compounds
作者:Xiao Li、Lei Zhang、Yu-Hua Xiao、Qi-Peng Guo、Chao-Shan Da、Hong Li、Xiaoju Liu、Xiangrong Ma、Yajun Ma
DOI:10.1134/s1070363216080247
日期:2016.8
Chiral Al/Zn heterobimetallic complexes are effective catalysts for the direct highly enantioselective aldol reaction of acetophenones with aromatic aldehydes. The Al site in the complex acts as a Lewis acid to activate aldehyde, whereas ethylzinc alkoxide plays a role of a Brønsted base to form a reactive zinc enolate with acetophenone. Distinct nature of two different metals contributes to the efficient
<i>N</i>-Triflylthiophosphoramide Catalyzed Enantioselective Mukaiyama Aldol Reaction of Aldehydes with Silyl Enol Ethers of Ketones
作者:Cheol Hong Cheon、Hisashi Yamamoto
DOI:10.1021/ol100233t
日期:2010.6.4
The first Brønsted acid catalyzed asymmetric Mukaiyama aldol reaction of aldehydes using silylenolethers of ketones as nucleophiles has been reported. A variety of aldehydes and silylenolethers of ketones afforded the aldol products in excellent yields and good to excellent enantioselectivities. Mechanistic studies revealed that the actual catalyst may be changed from the silylated Brønsted acid
A (S)-pyrrolidine sulfonamidecatalyzed asymmetric direct aldol reaction of aryl methyl ketones with aromatic aldehydes has been developed with moderate to good enantioselectivities. The study considerably broadens the substrate scope of chiral amines promoted aldol processes.