2024-03-29T10:07:30Zhttp://digital.csic.es/dspace-oai/requestoai:digital.csic.es:10261/191472009-11-29T23:00:00Zcom_10261_31com_10261_3col_10261_284
Carmona, Daniel
Lamata, M. Pilar
Viguri, Fernando
RodrÃguez, Ricardo
Lahoz, Fernando J.
Oro, Luis A.
2009-11-30T11:23:10Z
2009-11-30T11:23:10Z
2007-10-30
Chemistry - A European Journal 13(35): 9746-9756 (2007)
http://hdl.handle.net/10261/19147
10.1002/chem.200701140
Cationic half-sandwich complexes containing the [(5-C5Me5)M(Diphos*)] moiety (M=Rh, Ir; Diphos*=chiral diphosphine ligand) catalyze the cycloaddition of the nitrone 3,4-dihydroisoquinoline N-oxide (A) to methacrylonitrile (B) with excellent regio and endo selectivity and low-to-moderate enantioselectivity. The most active and selective catalyst, (SRh,RC)-[(5-C5Me5)Rh{(R)-Prophos)} (NC(Me)CCH2)](SbF6)2, has been isolated and fully characterized including the determination of the molecular structure by X-ray diffraction. The R-at-metal epimers of the complexes [(5-C5Me5)M{(R)-Prophos)}(NC(Me)CCH2)](SbF6)2 (M=Rh, Ir) isomerize to the corresponding S-at-metal diastereomers. The stoichiometric cycloaddition of A with B is catalyzed by diastereopure (SM,RC)-[(5-C5Me5)M{(R)-Prophos)}(NC(Me)CCH2)](SbF6)2 with perfect regio and endo selectivity and very good (up to 95 %) ee. The catalyst can be recycled up to nine times without significant loss of either activity or selectivity.
eng
closedAccess
Asymmetric catalysis
Cycloaddition
Iridium
Methacrylonitrile
Rhodium
Nitrones
Half-Sandwich Rhodium (and Iridium) Complexes as Enantioselective Catalysts for the 1,3-Dipolar Cycloaddition of 3,4-Dihydroisoquinoline N-Oxide to Methacrylonitrile.
artÃculo