Resolution through chiral ketones

Enantioselective enolate formation can also be achieved by kinetic resolution through preferential reaction of one of the enantiomers of a racemic chiral ketone such as 2-(f-butyl)cyclohcxanone (see Section 2.1.8 of Part A to review the principles of kinetic resolution). 

Furthermore, yeast treatment of the a-acetoxy ketone 53, bearing two oxygen substituents ( ) at a and affords the carbinol 54 in 20 % yield, somewhat less than 10 % of the (2R) diastereoisomer, and 70 % of recovered starting material. From the carbinol 54, crystalline 55 is obtained, which may be converted through suitable manipulation of the protecting groups and ozonolysis, into A-deoxy-D-talo-hexose 56. The minor diastereoisomer similarly affords A-deoxy-D-xylo-hexose 57. Thus, in the yeast treatment of 53, as the results of the enzymic kinetic resolution, the (2S, 4S, 5R) diol 55, a carbohydrate-like chiral synthon, is accessible out of eight possible isomers. 

In this communication we report a study of the stereochemical features of this catalytic process and the use of chiral diphosphine modified catalysts for the enantioselective synthesis of certain naturally ocurring lactones through kinetic resolution of a racemic mixture of the starting ketones. 

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