2024-03-29T00:30:13Zhttp://digital.csic.es/dspace-oai/requestoai:digital.csic.es:10261/557332020-05-26T08:59:41Zcom_10261_31com_10261_3col_10261_284
Study of the recycling possibilities for azabis(oxazoline)–cobalt complexes as catalysts for enantioselective conjugate reduction
Aldea, Luis
Fraile, José M.
García-Marín, Héctor
García, José I.
Herrerías, Clara I.
Mayoral, José A.
Pérez, Ignacio
6 páginas, 2 figuras, 6 tablas, 3 esquemas.
Azabis(oxazoline)–cobalt(II) complexes have been tested in multiphasic catalytic systems for enantioselective conjugate reduction of (E)-3-phenylbut-2-enoate with NaBH4. Immobilization by electrostatic interactions with laponite clay leads to excellent results in the first run, as a consequence of the role of the clay as an anion. However most of the reaction takes place in solution due to leaching of active complex, and the solids are not reusable. Covalent immobilization to Merrifield's resin does not allow the high enantioselectivity obtained in solution to be reached, and heterogeneous catalysts are again not reusable. Only the use of biphasic liquid systems allows an efficient recovery of the catalyst. The combination of a new ditopic ligand and 1,3-bis(2,2,2-trifluoroethoxy)propan-2-ol as a solvent for the catalyst phase is optimal to recycle the catalytic system with 90–96% ee for 5 runs.
Financial support from the European Union (project Solvsafe,
NMP2-CT-2005-011774), the Spanish Ministerio de Ciencia e
Innovación (projects CTQ2008-05138 and Consolider Ingenio
2010 CSD2006-0003), and the Diputación General de Aragón
(E11 Group co-financed by the European Regional Development
Funds) is gratefully acknowledged.
Peer reviewed
2012-09-07T07:02:11Z
2012-09-07T07:02:11Z
2010
artículo
http://purl.org/coar/resource_type/c_6501
Green Chemistry 12(3): 435-440 (2010)
1463-9262
http://hdl.handle.net/10261/55733
10.1039/B923137D
1463-9270
en
http://dx.doi.org/10.1039/B923137D
open
Royal Society of Chemistry (UK)