Asymmetric hydrogenation of C&z.dbd; C double bonds using Rh-complex under homogeneous, heterogeneous and continuous mode conditions

• Published in: Green chemistry : an international journal and green chemistry resource : GC Vol. 14; no. 4; pp. 1146 - 1151
• Main Authors: Balogh, Szabolcs, Farkas, Gergely, Madarasz, Jozsef, Szollosy, Aron, Kovacs, Jozsef, Darvas, Ferenc, Uerge, Laszlo, Bakos, Jozsef
• Format: Journal Article
• Language: English
• Published: 01.04.2012
• Subjects: Catalysts
• ISSN: 1463-9262; 1463-9270
• DOI: 10.1039/c2gc16447g

A green process for enantioselective hydrogenation of dehydroamino acid derivatives and dimethyl itaconate with a rhodium catalyst modified by a new phosphine-phosphoramidite has been developed providing 97.7-99.8% enantioselectivity in green solvents such as ethylene carbonate and propylene carbonate. The l-DOPA precursor was obtained by simple filtration in 71% yield with 99.5% ee. Dimethyl itaconate was hydrogenated under solvent-free condition at 50 degree C with 98.7% ee. The new rhodium complex was heterogenized on a mesoporous Al sub(2)O sub(3) support using phosphotungstic acid (PTA) as an anchoring agent and tested in heterogeneous batch and flow reaction modes. The supported catalyst was reused eight times in the batch mode with over 97% eeand used over 12 hours in the flow reaction mode with an average of 97% eein the asymmetric hydrogenation reaction of (Z)- alpha -acetamidocinnamic acid methyl ester.