64932-46-3Relevant academic research and scientific papers
Rh-DuPHOS-catalyzed enantioselective hydrogenation of enol esters. Application to the synthesis of highly enantioenriched α-hydroxy esters and 1,2-diols
Burk, Mark J.,Kalberg, Christopher S.,Pizzano, Antonio
, p. 4345 - 4353 (2007/10/03)
The asymmetric hydrogenation of α-(acetyloxy)- and α- (benzoyloxy)acrylates 4 catalyzed by cationic rhodium-DuPHOS complexes has been examined. A wide range of substrates (4) were prepared via a convenient Horner-Emmons condensation protocol, and subsequently hydrogenated under mild conditions (60 psi of H2) at substrate-to-catalyst ratios (S/C) of 500. Overall, enol ester substrates 4 were reduced by the cationic Et-DuPHOS-Rh catalysts with very high levels of enantioselectivity (93-99% ee). Importantly, substrates 4 bearing β-substituents could be employed as E/Z isomeric mixtures with no detrimental effect on the selectivity. Labeling studies indicated that no significant E/Z isomerization of the substrates occurs during the course of these reactions. Details concerning optimization of the reaction, interesting solvent effects, and deprotection procedures for the synthesis of highly enantioenriched α-hydroxy esters and 1,2-diols also are provided.
A CONVENIENT METHOD FOR THE PREPARATION OF ENOL ACETATES OF α-KETO ESTERS BY THE ALKYLATION OF CYANOHYDRIN SILYL ETHERS DERIVED FROM GLYOXYLIC ESTERS WITH BENZYL AND ALLYL HALIDES
Mukaiyama, Teruaki,Oriyama, Takeshi,Murakami, Masahiro
, p. 985 - 988 (2007/10/02)
Cyanohydrin silyl ethers, prepared by trimethylsilylcyanation of glyoxylic esters, smoothly react with LDA (lithium diisopropylamide) to yield the lithium salts, which in turn react with alkyl halides such as allyl bromide to give, after acetylation, the corresponding enol acetates of α-keto esters in good yields.
Asymmetric catalysis
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, (2008/06/13)
Catalytic asymmetric hydrogenation of a compound of the formula STR1 wherein R, R1 and R2 each independently represent hydrogen, substituted or unsubstituted alkyl having from 1 to 5 carbon atoms or substituted or unsubstituted aryl,
