Efficient <i>endo</i> Cycloisomerization of Terminal Alkynols Catalyzed by a New Ruthenium Complex with 8‐(Diphenylphosphino)quinoline Ligand and Mechanistic Investigation

Cai, Tao; Yu, Yang; Li, Weiwei; Qin, Wen‐Bing; Tang, Wen

doi:10.1002/chem.201703971

Cited by 27 publications

(16 citation statements)

References 127 publications

(109 reference statements)

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“…Cai et al illustrated that the cyclization selectivity can be shifted reliably in favor of the endo-dig cyclizations by changing the reaction mechanism [78]. The 5, 6, 7, and 8-endo-dig cycloisomerizations of terminal alkynols are possible under Ru-catalysis due to the formation and trapping of the Ru-vinylidene intermediate.…”

Section: Vinyl Ether Generation From Alkynesmentioning

confidence: 99%

Alkynes as Synthetic Equivalents of Ketones and Aldehydes: A Hidden Entry into Carbonyl Chemistry

et al. 2019

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The high energy packed in alkyne functional group makes alkyne reactions highly thermodynamically favorable and generally irreversible. Furthermore, the presence of two orthogonal π-bonds that can be manipulated separately enables flexible synthetic cascades stemming from alkynes. Behind these “obvious” traits, there are other more subtle, often concealed aspects of this functional group’s appeal. This review is focused on yet another interesting but underappreciated alkyne feature: the fact that the CC alkyne unit has the same oxidation state as the -CH2C(O)- unit of a typical carbonyl compound. Thus, “classic carbonyl chemistry” can be accessed through alkynes, and new transformations can be engineered by unmasking the hidden carbonyl nature of alkynes. The goal of this review is to illustrate the advantages of using alkynes as an entry point to carbonyl reactions while highlighting reports from the literature where, sometimes without full appreciation, the concept of using alkynes as a hidden entry into carbonyl chemistry has been applied.

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Section: Vinyl Ether Generation From Alkynesmentioning

confidence: 99%

Alkynes as Synthetic Equivalents of Ketones and Aldehydes: A Hidden Entry into Carbonyl Chemistry

et al. 2019

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“…8-Quinolylphosphanes are competent ligands for various functional coordination compounds, because they consist of a strongly -donating phosphane donor group and a -conjugated quinoline moiety and form a stable planar fivemembered chelate ring on coordination to a metal center (Cai et al, 2018;Hopkins et al, 2019;Scattolin et al, 2017). In one of our previous studies, it was revealed that 8-(diphenylphosphanyl)quinoline (PQ H ) in the simplest dichloridopalladium(II) complex, [PdCl 2 (PQ H )] (3), exhibits a strong trans influence of the diphenylphosphanyl donor group and an intermolecularstacking interaction between the quinoline ring systems (Suzuki et al, 2015).…”

Section: Chemical Contextmentioning

confidence: 99%

Crystal and molecular structures of dichloridopalladium(II) containing 2-methyl- or 2-phenyl-8-(diphenyphosphanyl)quinoline

2021

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The crystal structures of dichloridopalladium(II) complexes bearing 2-methyl- and 2-phenyl-8-(diphenylphosphanyl)quinoline, namely, dichlorido[8-(diphenylphosphanyl)-2-methylquinoline-κ2 N,P]palladium(II), [PdCl2(C22H18NP)] (1) and dichlorido[8-(diphenylphosphanyl)-2-phenylquinoline-κ2 N,P]palladium(II), [PdCl2(C27H20NP)] (2), were analyzed and compared to that of the 8-(diphenylphosphanyl)quinoline (PQH) analogue (3). In all three complexes, the phosphanylquinoline moiety acts as a bidentate P,N-donating chelate ligand. In the PQH complex (3), the PdII center has a typical planar coordination environment; however, both the methyl- and phenyl-substituted phosphanylquinoline (PQMe and PQPh, respectively) complexes (1) and (2) exhibit a considerable tetrahedral distortion around the PdII center, as parameterized by the τ4 values of 0.1555 (4) and 0.1438 (4) for (1) and (2), respectively. The steric interaction from the substituted group introduced at the 2-position of the quinoline ring enforces the cis-positioned Cl ligand to be displaced from the ideal coordination plane. Also, the ideally planar phosphanylquinoline five-membered chelate ring shows a large bending deformation by the displacement of the PdII center from the quinoline plane. In addition, in the phenyl-substituted complex (3), the coordinating quinolyl and the substituted phenyl rings are not co-planar to each other, having a dihedral angle of 33.08 (7)°. This twist conformation prohibits any intermolecular π–π stacking interaction between the quinoline planes, which is observed in the crystals of complexes (1) and (2).

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“…In 2018, Wen and co-workers reported cycloisomerizations of alcohol-tethered alkynes for oxacyclesw ith different ring sizes (5-to 8-membered) by employing Ru catalysts bearing 8-(diphenylphosphino)quinoline (DPPQ) (Scheme 10). [18] The Ruoxacarbene complexes isolated from the reactions served as evidencefor the Ru-vinylidene intermediacy.…”

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

confidence: 99%

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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Efficient endo Cycloisomerization of Terminal Alkynols Catalyzed by a New Ruthenium Complex with 8‐(Diphenylphosphino)quinoline Ligand and Mechanistic Investigation

Cited by 27 publications

References 127 publications

Alkynes as Synthetic Equivalents of Ketones and Aldehydes: A Hidden Entry into Carbonyl Chemistry

Alkynes as Synthetic Equivalents of Ketones and Aldehydes: A Hidden Entry into Carbonyl Chemistry

Crystal and molecular structures of dichloridopalladium(II) containing 2-methyl- or 2-phenyl-8-(diphenyphosphanyl)quinoline

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

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