Enantioselective hydrogenation over other

Enantioselective hydrogenation over other supported metals... 

Here we focus on the hydrogenation of trifluoromethyl ketones over a Pt/alumina catalyst modified by cinchonidine (CD) and some of its simple derivatives. Our recent research has revealed interesting similarities and dissimilarities in the enantioselective hydrogenation of trifluoromethyl ketones and other activated ketones, which observations may be useful for a future mechanistic study. 

Further studies for the hydrogenation of other prochiral ami-doacrylic acids confirmed that the high enantioselectivity of the catalyst is quite general. Several (Z)-2-acetamido-3-arylacrylic acids were hydrogenated with this catalyst and in all cases the desired products were found to have ee values of over 97%. More detailed data are summarized in Table 1. 

Enantioselective hydrogenation of MePy at RT and 10 bar of hydrogen over 6.3% Pt-silica modified with brucine resulted in (S)-MeLa with an ee of 20%, but no enantioselectivity was found in the hydrogenation of butane-2,3-dione. According to Wells et al. brucine adsorbs on a Pt surface to form cavities for the enantioselective adsorption of MePy but not for the diketone. On the other hand, Pt catalyst modified with the morphine alkaloid, oxycodone, works as an enantioselective catalyst in the hydrogenations of both MePy and... 

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