Abstract
The asymmetric reduction of keto esters accompanied by simultaneous dynamic and static resolution of chiral centers can be achieved by using a novel enzyme, YKER- I (Yeast Keto Ester Reductase- I). This reaction affords the corresponding hydroxy esters having three chiral centers. In the reduction of sec-alkyl 2-methyl-3-oxobutanoates, YKER-I affords the corresponding (2R, 3S, 1′R) -hydroxy esters selectively. Particularly, the reduction of 1, 3-dithianyl derivative affords the (2R, 3S, 1′R) -hydroxy ester in more than 95% purity out of possible eight stereoisomers. The reduction of dimethyl 2-acetyl -3-methylglutarate with this enzyme gives the corresponding (2R, 3R, 1′S) -hydroxy ester in more than 98% purity out of possible eight stereoisomers. This enzyme can introduce the three consecutive chiral centers in one stage of the reaction. No enzyme has been reported on the discrimination of remote and multichiral centers in acyclic compounds that have flexible skeletons.
