@Article{JCatal_194_445, author = {T. B{\"u}rgi and A. Baiker}, title = {{Model for enantioselective hydrogenation of $\alpha$-ketoesters over chirally modified Pt revisited: Influence of a-ketoester conformation}}, journal= {J. Catal.}, ISSN = {0021-9517}, volume= {194}, number= {2}, pages = {445-451}, url = {http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6WHJ-45D32KD-10&_user=9565874&_coverDate=09%2F10%2F2000&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_acct=C000043220&_version=1&_urlVersion=0&_userid=9565874&md5=abaa9ccd5f7908e8fcd386899237ad30&searchtype=a}, doi= {10.1006/jcat.2000.2958}, abstract = {{Interaction complexes between cinchonidine modifier and methyl pyruvate reactant proposed for the enantioselective hydrogenation over platinum catalysts have been calculated using {\em ab initio} methods. For {\em s-trans}-methyl pyruvate it was found that the complex yielding ({\em R})-methyl lactate upon hydrogenation was more stable than the corresponding pro-({\em S}) complex. The calculated energy difference of 1.8 kcal/mol corresponds to an enantiomeric excess of 92%, in good agreement with experiment. For the analogous complexes of {\em s-cis}-methyl pyruvate the energy difference is only 0.2 kcal/mol in favour of pro-({\em R}), corresponding to 17% enantiomeric excess. Due to the larger dipole moment of the {\em s-cis} conformer of methyl pyruvate its hydrogen-bonded complexes with cinchonidine are considerably more stable than the corresponding {\em s-trans} complexes. However, the predicted low enantiomeric excess for the {\em s-cis} conformer is in contrast with experiment. Possible reasons for this behaviour are discussed.}}, year = {2000} }