Michael addition to α,β-unsaturated arene ruthenium(II) cyclopentadiene complexes: endo nucleophilic addition

Moriarty, Robert M.; Enache, Livia A.; Gould, George L.; Wink, Donald J.; Gilardi, Richard

doi:10.1039/a707386k

Cited by 17 publications

(4 citation statements)

References 11 publications

(1 reference statement)

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“…Though not as thoroughly investigated, related arene-Ru(II) complexes also possess many attributes desirable in synthetic building blocks, such as ease of preparation and stability ,, This property has been exploited to great effect in the synthesis of a number of macrocyclic biaryl ethers and related materials from CpRu(II) building blocks (Cp = η 5 -cyclopentadienyl) …”

Section: Introductionmentioning

confidence: 99%

Functionalized Spiro- and Fused-Ring Heterocycles via Oxidative Demetalation of Cyclohexadienyl Ruthenium Complexes

2004

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Electron-rich alkoxy- and chloro-substituted azaspirocyclic cyclohexadienyl Ru(II) complexes have been converted to either azaspiro[4.5]decane derivatives or functionalized tetrahydroisoquinolines by treatment with suitable oxidizing agents. Copper(II) chloride was found to provide demetalated products in high yield relative to the other oxidants examined (FeCl(3), DDQ, CAN, [Cp(2)Fe][PF(6)], phenyliodine diacetate, IBX). In certain instances, the efficiency of oxidative demetalation was enhanced by the inclusion of chloride ion additives in the reaction. Pyridinium dichromate (PDC) was also found to effect the demetalation of a wide range of cyclohexadienyl Ru complexes; however, isolated yields of metal-free products were exceedingly low. The cyclohexadienyl ruthenium complexes used in this study were prepared from (arene)Ru(II) precursors; thus, the isolation of alicyclic cyclohexadienone derivatives upon demetalation constitutes completion of a Ru-mediated dearomatization process.

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Section: Introductionmentioning

confidence: 99%

Functionalized Spiro- and Fused-Ring Heterocycles via Oxidative Demetalation of Cyclohexadienyl Ruthenium Complexes

2004

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“…In summary, our mechanistic data strongly suggest that the ruthenium-catalyzed anti-Markovnikov hydroamination of arenes occurs by a new mechanism involving a rare example of catalytic chemistry through π-arene complexes. These findings suggest that further catalytic processes can be developed through Michael-type additions of nucleophiles other than amines to (η 6 -alkenylarene)metal complexes . Detailed studies on the effect of the electronic and steric properties of phosphine ligand, further modification of the catalyst to improve activity, and the use of this metal fragment for further catalytic reactions through π-arene intermediates are in progress.…”

mentioning

confidence: 98%

“…The most likely mechanism for the formation of 3a is direct nucleophilic attack of morpholine on the terminus of the styrene .…”

mentioning

confidence: 99%

Mechanistic Studies of Ruthenium-Catalyzed Anti-Markovnikov Hydroamination of Vinylarenes: Intermediates and Evidence for Catalysis through π-Arene Complexes

2005

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Studies are described that reveal the steps of the anti-Markovnikov hydroamination of vinylarenes with alkylamines catalyzed by Ru(COD)(2-methylallyl)2, bis(diphenylphosphino)pentane, and TfOH. Treatment of the catalyst components with an excess of styrene under the catalytic reaction conditions afforded a new ruthenium eta6-styrene complex with an ancillary tridentate PCP ligand. This ruthenium complex was active as catalyst for the hydroamination of styrene with morpholine to give the anti-Markovnikov adduct as a single regioisomer in high yield. Studies of the reactivity of the eta6-styrene complex revealed two reactions that comprise a catalytic cycle for anti-Markovnikov hydroamination: nucleophilic addition of morpholine to the ruthenium eta6-styrene complex to afford a ruthenium eta6-(2-aminoethyl)benzene complex and arene exchange of the ruthenium eta6-(2-aminoethyl)benzene complex with styrene to regenerate the ruthenium eta6-styrene complex. The addition of morpholine and the exchange of arene occurred with comparable rates. These results strongly suggest that the ruthenium-catalyzed anti-Markovnikov addition of alkylamines to vinylarenes occurs by a new reaction mechanism for hydroamination involving nucleophilic attack on the eta6-vinylarene complex and exchange of the aminoalkylarene complex product with free vinylarene. This mechanism is a rare example of catalytic chemistry through pi-arene complexes. These mechanistic data were used to select derivatives of the DPPP ligand that improve the rates of the catalytic process.

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“…In contrast, formation of 3 and 4 occurs readilydespite the geometrical constraints associated with the linear acetylene group and the strained nature of the resulting propenyl bridge (see below). This intramolecular hydroalkylation also represents the first known instance of a conjugate addition reaction at a metal-complexed phenylacetylene ligand 1 …”

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confidence: 91%

Intramolecular Hydroalkylation as a Route to Strained Dicationic Bis(arene) [3]Ruthenocyclophanes

et al. 2002

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Base-promoted intramolecular hydroalkylation of the carbon−carbon triple bond in the ruthenium bis(arene) complexes [(p-cymene)Ru(η 6-C6H5C⋮CR)][OTf]2 (1, R = Et; 2, R = Ph; OTf = O3SCF3) generates the strained [3]ruthenocyclophane complexes 3 and 4, in which a propenyl (−CH2CRCH−) group bridges the two arene ligands. The presence of the propenyl bridge results in a bent-metallocene structure for the [3]ruthenocyclophane cation in 4, with an angle of 11.8° between the arene ligands.

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Michael addition to α,β-unsaturated arene ruthenium(II) cyclopentadiene complexes: endo nucleophilic addition

Cited by 17 publications

References 11 publications

Functionalized Spiro- and Fused-Ring Heterocycles via Oxidative Demetalation of Cyclohexadienyl Ruthenium Complexes

Functionalized Spiro- and Fused-Ring Heterocycles via Oxidative Demetalation of Cyclohexadienyl Ruthenium Complexes

Mechanistic Studies of Ruthenium-Catalyzed Anti-Markovnikov Hydroamination of Vinylarenes: Intermediates and Evidence for Catalysis through π-Arene Complexes

Intramolecular Hydroalkylation as a Route to Strained Dicationic Bis(arene) [3]Ruthenocyclophanes

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