Up to 96% Enantioselectivities in the Hydrogenation of Fluorine Substituted (E)-2,3-Diphenylpropenoic Acids over Cinchonidine-Modified Palladium Catalyst
High enantioselectivities, up to 96%, were obtained in the hydrogenation of some disubstituted derivatives, unprecedented in the hydrogenation of prochiral unsaturated carboxylicacidsovermodified heterogeneous catalyst. The best optical purities were reached in the hydrogenation of derivates bearing a para-substituent on the β phenyl and an ortho-substituent on the α phenyl ring, respectively. The
Asymmetric transfer hydrogenation of 2,3-diphenylpropenoic acids over heterogeneous palladium catalysts modified by cinchona alkaloids
作者:György Szőllősi、Vivien Erzsébet Resch、Vanessza Judit Kolcsár
DOI:10.1016/j.jcat.2024.115290
日期:2024.1
supported palladium catalysts modified by dihydrocinchonidine carried out in ordinary laboratory glassware using easily available, cheap hydrogen donor, potassium formate. High conversions and good enantioselectivities were obtained in transfer hydrogenations of various acids substituted on phenyl rings. Results obtained with various acid derivatives and with few cinchona alkaloid modifiers indicated that
Heterogeneous Enantioselective Hydrogenation of Hydroxy-substituted (E)-2,3-diphenylpropenoic Acids over Pd/Al2O3 Modified by Cinchonidine
作者:György Szőllősi
DOI:10.1007/s10562-012-0777-5
日期:2012.3
The enantioselectivehydrogenation of (E)-2,3-diphenylpropenoic acids substituted by hydroxyl group has been studied over Pd/Al2O3 catalyst modified by cinchonidine. The effect of the acidic hydroxyl substituents was compared with that of the methoxy group in the same position. The para-hydroxyl substituent on the 3-phenyl ring had similar effect on the enantioselectivity as the methoxy group, whereas
enyl)propenoic acid showed 92%ee with an activity increase of 230%. It is considered that the difference is caused by the ortho-methoxy substituent on the α-phenyl ring. The substituent effect of the ortho-substituent on the α-phenyl ring demands the presence of an electron-donor substituent on the β-phenyl ring. A remarkable substituent effect was observed with 3-(p-methoxyphenyl)-2-(o-methoxyphenyl)propenoic