Chelation-controlled ester-derived titanium enolate aldol reaction: diastereoselective syn-aldols with mono- and bidentate aldehydes
摘要:
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.
Enantio- and Diastereoselective Reductive Aldol Reactions with Iridium-Pybox Catalysts
作者:Cun-Xiang Zhao、Matthew O. Duffey、Steven J. Taylor、James P. Morken
DOI:10.1021/ol015859f
日期:2001.6.1
[see reaction]. A catalytic amount of [(cod)IrCl]2 and indane-pybox converts diethylmethylsilane, methyl acrylate, and certain aldehydes to the derived reductive aldol adduct with good enantio- and diastereocontrol.
3R)--hydroxyesters in high optical purity. The corresponding (2R,3R)- isomer was obtained, with other strains, only in mixture with the isomer. These esters are useful precursors for chiral 2-methyl-3-hydroxy-butyrolactone synthons.
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.