Lewis Base Activation of Lewis Acids: Catalytic, Enantioselective Addition of Silyl Ketene Acetals to Aldehydes
作者:Scott E. Denmark、Gregory L. Beutner、Thomas Wynn、Martin D. Eastgate
DOI:10.1021/ja047339w
日期:2005.3.1
The concept of Lewisbase activation of Lewisacids has been reduced to practice for catalysis of the aldolreaction of silyl ketene acetals and silyl dienol ethers with aldehydes. The weakly acidic species, silicon tetrachloride (SiCl4), can be activated by binding of a strongly Lewis basic chiral phosphoramide, leading to in situ formation of a chiral Lewisacid. This species has proven to be a competent
Investigation of the Rh-Catalyzed Asymmetric Reductive Aldol Reaction. Expanded Scope Based on Reaction Analysis
作者:Albert E. Russell、Nathan O. Fuller、Steven J. Taylor、Pauline Aurriset、James P. Morken
DOI:10.1021/ol049591e
日期:2004.7.1
[reaction: see text] A series of experiments are described that suggest that the Rh-catalyzed reductive aldol reaction proceeds by addition of a Rh(I) hydride, generated in situ, to the reacting acrylate followed by a stereochemistry-controlling aldol addition reaction. On the basis of this hypothesis, reaction conditions are engineered that allow for increased substrate scope.
Conjugate reduction of aryl acrylates with tributyltin hydride in the presence of magnesium bromide diethyl etherate
作者:Satomi Hirasawa、Hajime Nagano、Yoko Kameda
DOI:10.1016/j.tetlet.2004.01.028
日期:2004.3
The conjugate reduction of aryl acrylates performed with tributyltinhydride in the presence of magnesium bromide diethyl etherate in dichloromethane gave the corresponding saturated esters in moderate to high yields. The reduction of α-methylene-γ-benzyloxycarboxylic acid esters proceeded syn-selectively, but α-methylene-β-oxycarboxylic acid esters afforded reductive elimination products under the
The catalytic asymmetric aldol reaction of aldehydes with unsubstituted and monosubstituted silyl ketene acetals: formation of anti-β-hydroxy-α-methyl esters
作者:Emma R. Parmee、Yaping Hong、Orin Tempkin、Satoru Masamune
DOI:10.1016/s0040-4039(00)91717-9
日期:1992.3
The title reaction with unsubstituted and monosubstituted silyl ketene acetals proceeds with high enantioselectivity, and in the latter case good diastereoselectivity favoring the anti-β-hydroxy-α-methyl esters in all reported cases.