Ofketones

Ionic liquid [bmimJPFg can be used as a solvent in yeast reduction [21]. The reduction ofketones with immobilized baker s yeast (alginate) in a 100 10 2 [bmimjPFfi ionic liquid water MeOH mix affords chiral alcohols (Figure 8.28). 

Reductions ofketones -alcohol dehydrogenase-catalyzed pNZYMES IN ORGANIC SYNTHESIS] (Vol 9)... 

Deoxygenation ofketones. Enol triflates, readily available by reaction of ketones and triflic anhydride catalyzed by this sterically hindered base, undergo rapid hydrogenolysis to the saturated hydrocarbon. Overall yields are 65-90%. ... 

A related group was developed by Gravel et al., for the protection ofketones. Thus, a diol derivative was used to form a ketal (under the usual acidic conditions), which was quite stable under acidic conditions (Scheme 13.6) [28, 29] but was, unfortunately, degraded under basic conditions. The introduction of a second aromatic group in the backbone, and provision of a single enantiomer of the diol (thus allowing the protection of chiral ketones without making pairs of diastereoisomers) partially solved the base-stability problem [30]. 

Finally, ligand 26 has been grafted onto three types of silica materials. Tu and coworkers developed a synthesis of silica bound 26 (Scheme 6.14) and applied it first to the asymmetric transfer hydrogenation ofketones [187] and later to imine 34 [184]. 

The value of the coefficient co can be determined for the chromatograph used and for the solvent in which CyOOH is dissolved. By chromatography either of the solution of pure authentic CyOOH or of the reaction solution in the initial period of the reaction when almost pure CyOOH is present in the solution and concentrations ofketone and alcohol are very low. 

Canos, A. C. Nemeth, L. T. Renz, M. Moscoso, J. G. The Oxidation ofKetones to Esters Using a Tin Substituted Zeolite Beta. 2002-00181291B, 2002. 

Istuno and coworkers reported an enantioselective reduction ofketones using a flow reactor, in which polymer-supported amino alcohol was fixed (Scheme 7.7). As butyl phenyl ketone and borane (1.2 equiv.) in THF were separately and continuously pumped into the reactor (overflow type), the desired alcohol was obtained in 84% yield with 83-93% ee. With analogous batch reactions, ee values were 81%-92%. Thus, with this reaction, both the flow and batch procedures gave similar results [41]. 

Noyori, R. and Ohkuma, T. (2001) Asymmetric catalysis by architectural and functional molecular engineering practical chemo- and stereoselective hydrogenation ofketones. Angew. Chem., Int. Ed., 40, 40-73. 

Grdger, H., Chamouleau, F., Orologas, N Rollmarm, C., Drauz, K., Hummel, W Weckbecker, A., and May, O. (2006) Enantioselective reduction ofketones with designer cells at high substrate concentrations highly efircient access to functionalized optically active alcohols. Angew. Chem., Int. Ed., 45, 5677-5681. 

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