Mechanistic insight into the pyridine enhanced a-selectivity in alkyne hydrothiolation catalysed by quinolinolate–rhodium(I)–N-heterocyclic carbene complexes

Palacios, Laura ; Di Giuseppe, Andrea (Universidad de Zaragoza) ; Artigas, María José ; Polo, Victor (Universidad de Zaragoza) ; Lahoz, Fernando J. (Universidad de Zaragoza) ; Castarlenas, Ricardo (Universidad de Zaragoza) ; Pérez-Torrente, Jesús J. (Universidad de Zaragoza) ; Oro, Luis A. (Universidad de Zaragoza)

Resumen: RhI–NHC–olefin complexes bearing a N,O-quinolinolate bidentate ligand have been prepared from [Rh(µ-OH)(NHC)(¿2-olefin)]2 precursors (olefin = cyclooctene, ethylene). The disposition of the chelate ligand with regard to the carbene in the square planar derivatives is strongly influenced by the steric hindrance exerted by the coordinated olefin. These complexes efficiently catalyzed the addition of thiophenol to phenylacetylene with good selectivity to a-vinyl sulfides, which can be increased up to 97% by addition of pyridine. Several key intermediates have been detected including the ¿1-alkenyl species resulting from alkyne insertion into a Rh–H bond. DFT calculations on the mechanism support a hydrometallation pathway that entails the oxidative addition of thiol, 2,1-insertion of the alkyne into the Rh–H bond, and reductive elimination as the rate-determining step. Remarkably, coordination of pyridine to the ß-alkenyl intermediate but not to the a-alkenyl, which results in a net stabilization, is the key for the Markovnikov selectivity.

Idioma: Inglés

DOI: 10.1039/c6cy01884j

Año: 2016

Publicado en: Catalysis Science and Technology 6, 24 (2016), 8548-8561
ISSN: 2044-4753

Factor impacto JCR: 5.773 (2016)

Categ. JCR: CHEMISTRY, PHYSICAL rank: 27 / 145 = 0.186 (2016) - Q1 - T1

Factor impacto SCIMAGO: 1.81 - Catalysis (Q1)

Financiación: info:eu-repo/grantAgreement/ES/DGA/E07
Financiación: info:eu-repo/grantAgreement/ES/MINECO/Consolider-Ingenio/CSD2009-0050
Financiación: info:eu-repo/grantAgreement/ES/MINECO/CTQ2013-42532-P

Tipo y forma: Article (PostPrint)

Área (Departamento): Área Química Inorgánica (Dpto. Química Inorgánica)
Área (Departamento): Área Química Física (Dpto. Química Física)