Asymmetric 1, 3-dipolar cycloaddition reactions between methacrylonitrile and nitrones catalysed by well-defined M(diphosphane) (M=Rh, Ir) complexes
Resumen: The cationic half-sandwich aqua-complexes (¿ 5-C5Me5)M(PP*)(H2O)]SbF6]2 M=Rh, Ir; PP* =(R)-Benphos, (R)-Cyphos, (2R, 4R)-Norphos] catalyse the 1, 3-dipolar cycloaddition reaction of nitrones with methacrylonitrile with perfect regioselectivity, low-to-perfect endo-selectivity and low-to-moderate enantioselectivity. The active species involved in the catalytic process, (¿ 5-C5Me5)M(PP*)(methacrylonitrile)]SbF6]2, have been isolated and characterised as mixtures of the (S)- and (R)-at-metal epimers. NMR measurements of these mixtures indicated that the (R M)-isomers epimerise to the corresponding (S M) counterparts. The molecular structure of the rhodium complex (S Rh, R C)-(¿ 5-C5Me5)Rh((R)-Benphos)(methacrylonitrile)]SbF6]2 has been determined by X-ray diffraction methods. Diastereomerically pure (S Rh, R C)-(¿ 5-C5Me5)Rh(PP*)(methacrylonitrile)]SbF6]2 compounds catalyse stoichiometrically the above mentioned dipolar cycloaddition reaction with up to 90% enantiomeric excess, thus indicating the influence of the metal handedness on the catalytic stereochemical outcome. Catalysts can be recycled up to three times without a significant loss of either activity or selectivity.
Idioma: Inglés
DOI: 10.1016/j.tetasy.2016.04.006
Año: 2016
Publicado en: Tetrahedron: Asymmetry 27, 11-12 (2016), [26 pp.]
ISSN: 0957-4166

Factor impacto JCR: 2.126 (2016)
Categ. JCR: CHEMISTRY, INORGANIC & NUCLEAR rank: 18 / 46 = 0.391 (2016) - Q2 - T2
Categ. JCR: CHEMISTRY, ORGANIC rank: 29 / 59 = 0.492 (2016) - Q2 - T2
Categ. JCR: CHEMISTRY, PHYSICAL rank: 80 / 145 = 0.552 (2016) - Q3 - T2

Factor impacto SCIMAGO: 0.754 - Inorganic Chemistry (Q2) - Physical and Theoretical Chemistry (Q2) - Organic Chemistry (Q2) - Catalysis (Q3)

Financiación: info:eu-repo/grantAgreement/ES/DGA/E63
Financiación: info:eu-repo/grantAgreement/ES/MINECO/Consolider-Ingenio/CSD2006-0015
Financiación: info:eu-repo/grantAgreement/ES/MINECO/CTQ2012-32095
Financiación: info:eu-repo/grantAgreement/ES/MINECO/CTQ2015-66079-P
Tipo y forma: Article (PostPrint)
Área (Departamento): Área Química Inorgánica (Dpto. Química Inorgánica)

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