1-Phenyl-1,2-propanedione enantiomeric excess

In the present study we are mainly concerned with regioselectivity, therefore enan-tioselectivity aspects of 1-phenyl, 1,2-propanedione will be mentioned only briefly. The enantiomeric excess (ee) of the main product B is defined as follows... 

Figure 3 Regioselectivity (rs) and enantiomeric excess (ee) in the hydrogenation of 1-phenyl-1,2-propanedione in ethyl acetate at 15°C. Catalyst 5wt.% Pt/Al203 modified in situ with different amounts of cinchonidine. Symbols ( ) regioselectivity and (O) enantiomeric excess.

Pt-MCM-41 with three different Pt contents was synthesized, characterized and tested in enantioselective hydrogenation of l-phenyl-l,2-propanedione. The maximum enantiomeric excess (ee) of (i )-l-hydroxy-1-phenylpropanone was 44% with the 15 wt.% Pt-MCM-41 modified with (-)-cinchonidine (compared to 54% obtained with 5 wt.% Pt/Al203). The highest ee obtained with 15 wt.% Pt-MCM-41 was due to the slightly larger Pt particles. Further optimization of the reaction conditions is a very important task in order to utilize mesoporous materials in enantioselective hydrogenation. 

Fig. 7. 23 Dependence of enantiomeric excess on solvent-dielectric constant in hydrogenation of 1-phenyl-1,2-propanedione. (From Toukoniitty, P. Maki-Arvela, J. Kuusisto, V. Nieminen, J. Paivarinta, M. Hotokka, T. Salmi, D.Yu. Murzin, J. Mol. Catal. A Chem. 192 (2003) 135. Copyright 2003 Elsevier).

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See also in sourсe #XX -- [ , ]

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