Generation of (<i>E</i>)-Silylketene Acetals in a Rhodium-DuPhos Catalyzed Two-Step Reductive Aldol Reaction
作者:Cun-Xiang Zhao、Jonathan Bass、James P. Morken
DOI:10.1021/ol016279l
日期:2001.9.1
[GRAPHICS]Mechanistic studies employing in situ NMR analysis implicate intermediate silicon enolates as reactive intermediates in the Rh-DuPhos catalyzed two-step reductive aldol reaction with Cl2MeSiH. These enolates undergo noncatalyzed reaction with a variety of aldehydes to give the derived syn-aldol adduct in high yields and diastereoselection.
Chelation-controlled ester-derived titanium enolate aldol reaction: diastereoselective syn-aldols with mono- and bidentate aldehydes
作者:Arun K Ghosh、Jae-Hun Kim
DOI:10.1016/s0040-4039(02)01113-9
日期:2002.8
A chelation-controlled and highly diastereoselective synthesis of syn-aldols is described. Aldol reaction of (S)-valinolderived ester with a variety of aldehydes proceeded with high syn-diastercoselectivities (up to 99:1) and isolated yields (94%). (C) 2002 Elsevier Science Ltd. All rights reserved.
Asymmetric Aldol Reaction with Diisopinocampheyl Enolborinates of Propionates
A convenient and general, reagent-controlled, diastereo- and enantioselective aldol reaction of diisopinocampheylboron enolates of esters, followed by reduction, has been developed as an alternative to crotylboration-ozonolysis. This protocol was then exploited for the double diastereoselective synthesis of the C11-C17 subunit of (-)-dictyostatin.
The chemistry of enoxysilacyclobutanes: highly selective, uncatalyzed aldol additions
作者:Scott E. Denmark、Brian D. Griedel、Diane M. Coe
DOI:10.1021/jo00057a002
日期:1993.2
O-(Silacyclobutyl)ketene acetals derived from esters, thiol esters, and amides reacted with a variety of aldehydes at room temperature without the need for catalysts. The O,O-ketene acetal of E-configuration reacted rapidly to afford the syn aldol products with high diastereoselectivity (93/7-99/1).
Lipase catalyzed enantioselective hydrolysis of 2-methyl 3-acetoxy esters