On the enantioselective hydrogenation of isomeric β-acylamido β-alkylacrylates with chiral Rh(I) complexes—comparison of phosphine ligands and substrates

✍ Scribed by Detlef Heller; Jens Holz; Igor Komarov; Hans-Joachim Drexler; Jingsong You; Karheinz Drauz; Armin Börner

• Book ID: 104359532
• Publisher: Elsevier Science
• Year: 2002
• Tongue: English
• Weight: 231 KB
• Volume: 13
• Category: Article
• ISSN: 0957-4166
• DOI: 10.1016/s0957-4166(02)00717-6

✦ Synopsis

The rhodium(I)-catalyzed enantioselective hydrogenation of E-and Z-configured b-acylamido b-alkylacrylates as well as of isomeric mixtures has been investigated. As ligands 1,2-bisphospholanes like DuPHOS, BPE and Me 4 -BASPHOS have been tested, but also diphosphines forming seven-membered chelates such as DIOP. The effect of additional oxy groups in the diphosphine ligand on rate and enantioselectivity was likewise elucidated. In general, with all catalysts screened the hydrogenation is strongly sensitive to the E/Z-geometry of the substrate. E-Substrates are converted with good or excellent enantioselectivites into the desired b-amino acid derivatives. The hydrogenation of Z-substrates showed the known H 2 -pressure dependency of the ee.