Chelate-Assisted Oxidative Coupling Reaction of Arylamides and Unactivated Alkenes: Mechanistic Evidence for Vinyl C−H Bond Activation Promoted by an Electrophilic Ruthenium Hydride Catalyst

Kwon, Ki Hyeok; Lee, Do W.; Yi, Chae S.

doi:10.1021/om100764c

Cited by 86 publications

(43 citation statements)

References 36 publications

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“…Oxidative couplings of arenes with allyl esters 17,25 have been reported to form mixtures of branched and linear isomers, and directed olefinations of benzamides with isobutylene or cyclopentene occur in low yield and generate large amounts of alkylarene side-products. 19 The olefinations of tolyltriazole N-oxide, 29 benzothiazole, 28 and thiophene 25 with 1-octene have been reported, but just one example of each was described, and all formed complex mixtures of products in low yield.…”

Section: ■ Introductionmentioning

confidence: 99%

Iridium-Catalyzed Oxidative Olefination of Furans with Unactivated Alkenes

Sevov

Hartwig

2014

J. Am. Chem. Soc.

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The oxidative coupling of arenes and alkenes is an attractive strategy for the synthesis of vinylarenes, but reactions with unactivated alkenes have typically occurred in low yield. We report an Ir-catalyzed oxidative coupling of furans with unactivated olefins to generate branched vinylfuran products in high yields and with high selectivities with a second alkene as the hydrogen acceptor. Detailed mechanistic experiments revealed catalyst decomposition pathways that were alleviated by the judicious selection of reaction conditions and application of new ligands.

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Section: ■ Introductionmentioning

confidence: 99%

Iridium-Catalyzed Oxidative Olefination of Furans with Unactivated Alkenes

Sevov

Hartwig

2014

J. Am. Chem. Soc.

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“…26 Catalytic methods to fulvenes and related benzocyclic compounds have not been extensively developed, although this group and others have recently reported catalytic C–H coupling methods to synthesize fulvene and structurally related indene derivatives. 21a,27 From a synthetic point of view, one of the most salient features of our intramolecular coupling method is that synthetically valuable indene and fulvene derivatives are efficiently constructed without employing any reactive reagents or additives.…”

Section: Resultsmentioning

confidence: 99%

“…21 We observed an unusual selectivity pattern of the catalyst 1 in mediating these coupling reactions in that C–H and C=O olefination products are directly resulted from the coupling of arylketones with alkenes, 21c instead of the ortho -arene C–H insertion products typically observed in Ru-catalyzed C–H activation reactions. 22 We have been able to extend the synthetic utility of the C–H olefination method to the conjugate addition reaction of α,β-unsaturated carbonyl compounds in affording tetrasubstituted olefins.…”

Section: Introductionmentioning

confidence: 97%

Scope and Mechanistic Study of the Coupling Reaction of α,β-Unsaturated Carbonyl Compounds with Alkenes: Uncovering Electronic Effects on Alkene Insertion vs Oxidative Coupling Pathways

Kwon

Lee

2011

Organometallics

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The cationic ruthenium-hydride complex [(C6H6)(PCy3)(CO)RuH]+BF4− (1) was found to be a highly effective catalyst for the intermolecular conjugate addition of simple alkenes to α,β-unsaturated carbonyl compounds to give (Z)-selective tetrasubstituted olefin products. The analogous coupling reaction of cinnamides with electron-deficient olefins led to the oxidative coupling of two olefinic C–H bonds in forming (E)-selective diene products. The intramolecular version of the coupling reaction efficiently produced indene and bicyclic fulvene derivatives. The empirical rate law for the coupling reaction of ethyl cinnamate with propene was determined as: rate = k[1]1[propene]0[cinnamate]−1. A negligible deuterium kinetic isotope effect (kH/kD = 1.1±0.1) was measured from both (E)-C6H5CH=C(CH3)CONHCH3 and (E)-C6H5CD=C(CH3)CONHCH3 with styrene. In contrast, a significant normal isotope effect (kH/kD = 1.7±0.1) was observed from the reaction of (E)-C6H5CH=C(CH3)CONHCH3 with styrene and styrene-d10. A pronounced carbon isotope effect was measured from the coupling reaction of (E)-C6H5CH=CHCO2Et with propene (13C(recovered)/13C(virgin) at Cβ = 1.019(6)), while a negligible carbon isotope effect (13C(recovered)/13C(virgin) at Cβ = 0.999(4)) was obtained from the reaction of (E)-C6H5CH=C(CH3)CONHCH3 with styrene. Hammett plots from the correlation of para-substituted p-X-C6H4CH=CHCO2Et (X = OCH3, CH3, H, F, Cl, CO2Me, CF3) with propene and from the treatment of (E)-C6H5CH=CHCO2Et with a series of para-substituted styrenes p-Y-C6H4CH=CH2 (Y = OCH3, CH3, H, F, Cl, CF3) gave the positive slopes for both cases (ρ = +1.1±0.1 and +1.5±0.1, respectively). Eyring analysis of the coupling reaction led to the thermodynamic parameters, Δ H‡ = 20±2 kcal mol−1 and S‡ = −42±5 e.u. Two separate mechanistic pathways for the coupling reaction have been proposed on the basis of these kinetic and spectroscopic studies.

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“…[12] Bereits in früheren Studien wurde dieser monomere Ru-Komplex, der rçntgenkristallographisch und durch Mehrkern-NMR-Spektroskopie charakterisiert wurde, als Katalysator für die C-H-aktivierende Kupplung von Alkenen und Arylketonen, [13] Arylamiden, [14] Alkenen [15] und -was am bemerkenswertesten ist -primären Alkoholen eingesetzt. [12] Bereits in früheren Studien wurde dieser monomere Ru-Komplex, der rçntgenkristallographisch und durch Mehrkern-NMR-Spektroskopie charakterisiert wurde, als Katalysator für die C-H-aktivierende Kupplung von Alkenen und Arylketonen, [13] Arylamiden, [14] Alkenen [15] und -was am bemerkenswertesten ist -primären Alkoholen eingesetzt.…”

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