One-Pot Formation of Functionalized Indole and Benzofuran Derivatives Using a Single Bifunctional Ruthenium Catalyst

Nair, Reji N.; Lee, Paul J.; Grotjahn, Douglas B.

doi:10.1007/s11244-010-9529-1

Cited by 15 publications

(6 citation statements)

References 25 publications

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“…[5] Alternatively, additive-free methods are possible with cooperative [6] catalysts that contain a Brønsted base as part of a supporting ligand. [7] We have systematically studied structure-performance relationships of [Ru(Cp/Cp*)(P R 2 N R' 2 )(MeCN)]PF 6 (1, Cp; 2, Cp*) catalysts that contain the cooperative P R 2 N R' 2 (1,5-R'-3,7-R-1,5diaza-3,7-diphosphacyclooctane) ligand (Figure 1a). [8] The pendent amine groups effectively promote proton transfer steps if the amine is moderately basic (i. e. R'=Ph).…”

Section: Introductionmentioning

confidence: 99%

Origin of Stability and Inhibition of Cooperative Alkyne Hydrofunctionalization Catalysts

2021

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New entries to the [Ru(Cp/Cp*)(P R 2 N R' 2 )(MeCN)]PF 6 catalyst family were synthesized, including a Cp complex (R=Cy; R'=Ph) and two Cp* complexes (R=Cy, Ph; R'=Ph). These and other derivatives were used for the intramolecular hydroamination of 2-ethynylaniline to elucidate trends in catalytic lifetime and rate. The readily accessible [Ru(Cp)(P Cy 2 N Ph 2 )(MeCN)]PF 6 derivative showed comparable lifetime to [Ru(Cp)(P tÀ Bu 2 N Ph 2 )(MeCN)] PF 6 , the previous optimal catalyst. Donor-free 'active' catalysts, [Ru(Cp/Cp*)(P Cy 2 N Ph 2 )]PF 6 , were prepared and their thermal stability was assessed. The relatively high stability of the Cp derivative was explained by the capacity of the P Cy 2 N Ph 2 ligand to coordinate in a k 3 -(P,P,Ar) mode, which protects the lowcoordinate species. This coordination mode is inaccessible with the Cp* derivative. Additionally, [Ru(Cp*)(P Cy 2 N Ph 2 )]PF 6 readily activated the CÀ Cl bond of the solvent dichloromethane. Variable time normalization analysis (VTNA) revealed that the indole product inhibited the catalyst [Ru(Cp)(P Cy 2 N Ph 2 )(MeCN)] PF 6 , which slowed catalytic rates.

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Section: Introductionmentioning

confidence: 99%

Origin of Stability and Inhibition of Cooperative Alkyne Hydrofunctionalization Catalysts

2021

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“…Furthermore, deuterated compounds are widely used in various research fields (e.g., synthetic chemistry, pharmaceutical science, and materials science) and the D-alkyne functional group is valuable for the synthesis of other deuterated functional groups, such as D-alkenes or D-alkanes, 13,27-29 D-ketones, 30 and D-aromatics. 31 Our findings related to D/H exchange of terminal alkynes provide further insights for the synthesis of D-labeled compounds using D-alkynes.…”

Section: Discussionmentioning

confidence: 72%

Deuteration of terminal alkynes realizes simultaneous live cell Raman imaging of similar alkyne-tagged biomolecules

et al. 2021

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“…The formation of dihydropyrans was proposed to involve Ru–vinylidene species as intermediates. In the same year, Grotjahn and co‐workers reported one‐pot catalytic conversions of aniline‐ and phenol‐tethered alkynes into functionalized indoles and benzofurans, respectively using a single bifunctional Ru catalyst (Scheme ) . The Ru catalyst itself can induce cyclizations of aniline‐ and phenol‐tethered alkynes while the pyridine groups on the phosphine ligand serve as proton shuttles.…”

Section: Recent Progress Of Ruthenium‐induced Cyclization Of Alkynesmentioning

confidence: 99%

“… Ru‐catalyzed cyclizations of aniline‐ and phenol‐tethered alkynes into indoles and benzofurans, respectively developed by Grotjahn and co‐workers …”

Section: Recent Progress Of Ruthenium‐induced Cyclization Of Alkynesmentioning

confidence: 99%

“…In the same year,G rotjahn and co-workersr eported one-pot catalytic conversions of aniline-and phenol-tethered alkynes into functionalized indoles and benzofurans,r espectively using as ingle bifunctional Ru catalyst( Scheme7). [11,12] The Ru catalyst itself can inducec yclizations of aniline-a nd phenol-tethered alkynes while the pyridine groups on the phosphine ligand serve as proton shuttles. The cyclizations were proposed to stem from Ru-vinylidene intermediacy.…”

Section: Catalytic Ru II -Mediated Cyclizations Of N/o-functionalizedmentioning

confidence: 99%

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Ruthenium‐Induced Cyclization of Heteroatom‐Functionalized Alkynes: Progress, Challenges and Perspectives

Chung

Yeung

Wong

2020

Chemistry A European J

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Metal-induced cyclization of functionalized alkynes represents one of the most general approaches to prepare organic heterocycles. AlthoughR u II centers are well-established to promote alkyne to vinylidener earrangements and many Ru II -mediated alkyne cyclizations have been rationalized to be the resultso fp ost-vinylidene transformations, recent discoveries indicate that Ru II centers can serve as electrophiles and induce alkyne cyclizationsw ithoutv inylidene intermediacy. In this Minireview,a no verview of the Ru II -induced cyclization of heteroatom-functionalized alkynes in the last decadei sp rovided, with an emphasis on the discoveries and validations of the unconventional "non-vinylidene-involving" pathways. Recent Progress of Ruthenium-Induced Cyclization of AlkynesResearcho nt he activation of heteroatom-functionalizeda lkynes by Ru II complexes for oxygen-and nitrogen-containing heterocycles of different ring sizes (5-to 8-membered) continues unabated. Most reported Ru complexes ares upported by Cp (Cp = cyclopentadienyl) or structurally analogous h 5 -ligands, amine-or mixed amine/phosphine-basedc helates. In general, the catalyst loadings are almost lower than 10 mol %a nd can be as low as 0.5 mol %. Although the cyclizations are mostly demonstrated with terminala lkynes, there are increasing number of successful reports on cyclizing internal alkynes.T he use of proton shuttles( internal or external bases which facilitate protont ransfer) has been found to be critical in many of these catalytic reactions. Noteworthy,s everal recent studies clearly indicatet hat the "vinylidene-involving" and "non-vinylidene-involving" pathwaysd epicted in Scheme 1are competing mechanisms. In this section, Ru-catalyzedc yclization of heteroatom-functionalized alkynes in the last decade is discussed in chronological order,e xcept in the cases of certain serial or outlying works. Catalytic Ru II -mediated cyclizations of N/O-functionalized alkynesthrough "vinylidene-involving" pathwaysThe successful isolations of Fe-, Ru-, and Os-oxacarbene complexesf rom the reactions between homopropargylic/bis-ho-Scheme1.(a) Established mechanisms for the formation of Ru-vinylidene species. (b) Electrophilic cyclizationso fheteroatom-functionalized alkynes induced by Ru.[a] Dr.Scheme8.Ru-catalyzed cycloisomerizations of alkynols into 5-, 6-and 7membered oxacycles developed by Jia and co-workers. [13,14] Scheme7.Ru-catalyzed cyclizationso fa niline-and phenol-tethered alkynes into indoles and benzofurans, respectively developed by Grotjahn and coworkers. [11,12] Scheme9.Ru-catalyzed cycloisomerizations of hydroxyl-and amine-substituteda lkynes into isochromenes, indolesa nd isoquinolinones developedby Blacquiereand co-workers. [15][16][17] Scheme10. Ru-catalyzed cycloisomerizations of alcohol-tethered alkynes developedb yWen and co-workers. [18] Chem.E ur.Scheme20. Isolation of, and proposed formation mechanism for 4a.The synthesis of 4b is also depictedf or reference [31].Scheme21. Isolation of, and proposed formation mechanism for...

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One-Pot Formation of Functionalized Indole and Benzofuran Derivatives Using a Single Bifunctional Ruthenium Catalyst

Cited by 15 publications

References 25 publications

Origin of Stability and Inhibition of Cooperative Alkyne Hydrofunctionalization Catalysts

Origin of Stability and Inhibition of Cooperative Alkyne Hydrofunctionalization Catalysts

Deuteration of terminal alkynes realizes simultaneous live cell Raman imaging of similar alkyne-tagged biomolecules

Ruthenium‐Induced Cyclization of Heteroatom‐Functionalized Alkynes: Progress, Challenges and Perspectives

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