Reduction of acyl enolates of .ALPHA.-substituted .BETA.-keto esters by bakers' yeast.

Reduction of Acyl Enolates of a-Substituted /?-Keto Esters by Bakers' Yeast

Enol esters of 2-substituted-3-oxoalkanoates of (Z)-configuration were reduced by bakers' yeast to chiral 2-substituted-3-hydroxyalkanoates. The sy/f-selectivities of this reaction increased compared with those of the reduction of the corresponding racemic keto esters. The reaction mayproceed via an asymmetric hydrolysis of the enol esters, followed by the reduction of the resulting carbonyl gr...

Stereochemical Control of Yeast Reduction of α-Keto Esters in an Organic Solvent

Highly effective chiral ortho-substituted BINAPO ligands (o-BINAPO): applications in Ru-catalyzed asymmetric hydrogenations of beta-aryl-substituted beta-(acylamino)acrylates and beta-keto esters.

A novel family of chiral ortho-substituted BINAPO ligands (o-BINAPO) were synthesized from BINOL, and their Ru complexes were highly efficient catalysts for asymmetric hydrogenation of beta-aryl-substituted beta-(acylamino)acrylates and beta-aryl-substituted beta-keto esters. The Ru-bisphosphinite catalysts can tolerate an E/Z mixture of beta-aryl-substituted beta-(acylamino)acrylates. These hi...

THE CALCIUM BINDING SITES OF THE BAKERS' YEAST TRANSKETOLASE

The calcium binding sites of Bakers' Yeast Transketolase (TK) was elucidated by estimating the pKa values of the functional groups that bind to calcium. These pKa's were found to be 6.25 and 7.2 relating to the pKa's of the two immidazol moieties of histidine residues on the enzyme. The rate of the binding of calcium to the enzyme was obtained separately as a function of pH. Maximum values ...

Synthesis of alpha-keto esters by the rhodium-catalysed reaction of cyanoformate with arylboronic acids.

An arylrhodium(I) species selectively reacts with the cyano group of ethyl cyanoformate to afford the corresponding alpha-keto ester in good yield.