Chiral rhodium(bisoxazolinylphenyl) complexes (1 mol %) efficiently catalyze the asymmetric reductive aldol reaction of aldehydes and alpha,beta-unsaturated esters at 50 degrees C for ca. 0.5-1.0 h with several hydrosilanes to give the corresponding beta-hydroxypropionates with extremely high anti-selectivity (up to 98%) and enantioselectivity (up to 96% ee). The stereochemical outcome is likely due
ClickFerrophos families and tested for the Cu(I)-catalyzed asymmetric reductivealdolreaction of ketones and aldehydes with an acrylic ester in the presence of phenylsilane. The Cu(I)-ClickFerrophos complex is efficient for the reaction of ketones with methylacrylate to afford the erythro adducts both highlydiastereo- and enantioselectively; the diastereomeric ratio of erythrolthreo is improved when compared
(Diisopinocampheyl)borane-Mediated Reductive Aldol Reactions of Acrylate Esters: Enantioselective Synthesis of <i>Anti</i>-Aldols
作者:Christophe Allais、Philippe Nuhant、William R. Roush
DOI:10.1021/ol401679g
日期:2013.8.2
The (diisopinocampheyl)borane promoted reductive aldol reaction of acrylate esters 4 is described. Isomerization of the kinetically formed Z(O)-enolborinate 5Z to the thermodynamic E(O)-enolborinate 5E via 1,3-boratropic shifts, followed by treatment with representative achiral aldehydes, leads to anti-alpha-methyl-beta-hydroxy esters 9 or 10 with excellent diastereo- (up to >= 20:1 dr) and enantioselectivity (up to 87% ee). The results of double asymmetric reactions of 5E with several chiral aldehydes are also presented.
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.