Asymmetric hydrogenation unfunctionalized ketones

The asymmetric hydrogenation of unfunctionalized ketones is a much more challenging task than that of functionalized ketones [3 j, 115]. Many chiral catalysts which are effective for functionalized ketones do not provide useful levels of enantioselectivity for unfunctio-nalized ketones, due to a lack of secondary coordination to the metal center. Zhang demonstrated the enantioselective hydrogenation of simple aromatic and aliphatic ketones using the electron-donating diphosphane PennPhos, which has a bulky, rigid and well-defined chiral backbone, in the presence of 2,6-lutidine and potassium bromide [36]. 

As noted previously, one of the most dramatic advances in asymmetric hydrogenation over the past tu o decades has been the development of ruthenium catalysts for the hydrogenation of ketones. Tltese hydrogenations can be divided into the hydrogenation of "functionalized" ketones and "unfunctionalized" ketones. "Functionalized" ketones... 

Hydrogenation is now the most utilized homogeneous catalytic reaction in process chemistry for the synthesis of enantioenriched material. The scope of highly enantioselective hydrogenation is spectacular. It ranges from olefins and ketones functionalized with ligating substituents to unfunctionalized alkenes and ketones. Examples of the asymmetric... 

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