Reactions of Aromatic S‐ and O‐Enynes with Two Methyl Substituents on the Olefinic Unit Assisted by a Ruthenium Complex: Tandem Cyclization and Product Selectivity

Feng, Yi‐Jhen; Lai, Ying-Hsuan; Lin, Ying‐Chih; Huang, Shou‐Ling; Liu, Yi-Hung

doi:10.1002/asia.201301264

Cited by 12 publications

(6 citation statements)

References 105 publications

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“…In our previous investigation, visible light promoted effectively the oxidation of metal carbenes to give aldehydes. When compared to the oxygenations of analogous carbene complexes with either a naphthothiophene14b or a benzothiophene,25 the reactions of 2a – 2c to yield 4a – 4c are less efficient. The oxygenation of 2a was checked both in the presence (Table 1, Entry 3) and in the absence of visible light (Table 1, Entry 4) for 12 h. The yield of 4a improved from 47 % in the dark to 60 % under visible light; therefore, visible light only has a slightly promotional effect.…”

Section: Resultsmentioning

confidence: 99%

Cyclizations of Aryl Enynes Containing Propargyl Alcohol and Diallylamine Groups to Yield Indolecarbaldehydes Induced by Ruthenium Complexes

Feng¹,

Tsai²,

Huang³

et al. 2014

Eur J Inorg Chem

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The reactions of RuCl(PPh 3 ) 2 Cp ([Ru]Cl, Cp = cyclopentadienyl) with aryl enynes 1a-1c containing propargyl alcohol and diallylamine groups on the aryl ring give the carbene complexes 2a-2c, each of which contains an indole group. With an additional methylene group, the aryl enyne 1d reacts with [Ru]Cl to afford the dihydroisoquinoline complex 3d. For 1a-1d, the C-N bond-forming process occurs when the triple bond is π-coordinated to the metal center. The reaction of [Ru]Cl with the aryl enyne 1e containing an isoxazole group affords the carbene complex 2e by a C-C bond forma-[a] We have recently reported the mild oxygenation of ruthenium carbene complexes with O 2 /NEt 3 to obtain high yields of aldehydes. [14] As an extension of our previous study, we further develop ruthenium-catalyzed cyclization reactions of propargyl alcohol with nitrogen-containing enynes to afford carbene complexes. Herein, we report the synthesis of these carbene complexes, each with a conjugated ring structure, and when these complexes are treated with O 2 /NEt 3 they afford aldehydes in high yields by oxidation of the carbene ligand.

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Section: Resultsmentioning

confidence: 99%

Cyclizations of Aryl Enynes Containing Propargyl Alcohol and Diallylamine Groups to Yield Indolecarbaldehydes Induced by Ruthenium Complexes

Feng¹,

Tsai²,

Huang³

et al. 2014

Eur J Inorg Chem

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“…Previously, we reported the Ru-mediated cyclization, skeletal rearrangement and cycloisomerization of enynes with propargylic functionality . For example, cyclization of several 1,8-enynes (Scheme ) consisting of the propargylic alcohol and the olefinic part containing an internal methyl group was studied . The two unsaturated functional groups are linked either by an aromatic or by a more flexible carbon chain.…”

Section: Introductionmentioning

confidence: 84%

Domino Cyclization of 1,n-Enynes (n = 7, 8, 9) Giving Derivatives of Pyrane, Chromene, Fluorene, Phenanthrene and Dibenzo[7]annulene by Ruthenium Complexes

Chen

et al. 2016

J. Org. Chem.

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Cyclization of the ether enyne 1 catalyzed by [Ru]NCCH3(+) ([Ru] = Cp(PPh3)2Ru) in CHCl3 generates a diastereomeric mixture of the substituted tetrahydropyran 11. Presumably, formation of an allenylidene complex is followed by a cyclization by nucleophilic addition of the olefinic group to Cγ of the ligand giving a boat-like six-membered ring. The diastereoselectivity is controlled by the 1,3-diaxial interaction. The vinylidene complex 7, a precursor of 11, is obtained from 1 and [Ru]Cl. In a mixture of MeOH/CHCl3, the domino cyclization of 1 further affords 14a, a chromene product catalytically. The second cyclization proceeds via nucleophilic addition of the resulting olefinic unit to Cα of 7. But the ether enyne 3 with a cyclopentyl ring on the olefinic unit undergoes only single cyclization due to steric effect. The propargyl alcohol and the two terminal methyl groups on the olefinic unit shape the cyclization. Thus, similar all-carbon 1,n-enynes (n = 7, 8, 9) 4-6 each with an aromatic linker undergo direct domino cyclization catalyzed by [Ru]NCCH3(+), to give derivatives of tricyclic fluorene, phenanthrene and dibenzo[7]annulene, respectively, with no intermediate observed.

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“… Isolation of, and proposed formation mechanisms for 3 a , 3 b and 3 c . The synthesis of 3 a’ – 3 c’ is also depicted for reference …”

Section: Validating “Non‐vinylidene‐involving” Pathways Through Isolamentioning

confidence: 99%

“…Later,t he same group reported the isolation of am ixture of Ru-benzothiophenyl-carbene (3a), -alkenyl (3b)a nd -vinylidene (3c)c omplexesf rom the reactions betweenp ropargylic thioether S3 and [CpRu(PPh 3 ) 2 Cl] (Scheme 19). [29,30] Complexes 3a and 3b were rationalized to be derived from" non-vinylidene-involving" pathway whereas 3c were from "vinylidene-involving" pathways. The analogous primedd erivatives 3a'-3c' were obtained by replacing S3 by S3'.…”

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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Reactions of Aromatic S‐ and O‐Enynes with Two Methyl Substituents on the Olefinic Unit Assisted by a Ruthenium Complex: Tandem Cyclization and Product Selectivity

Cited by 12 publications

References 105 publications

Cyclizations of Aryl Enynes Containing Propargyl Alcohol and Diallylamine Groups to Yield Indolecarbaldehydes Induced by Ruthenium Complexes

Cyclizations of Aryl Enynes Containing Propargyl Alcohol and Diallylamine Groups to Yield Indolecarbaldehydes Induced by Ruthenium Complexes

Domino Cyclization of 1,n-Enynes (n = 7, 8, 9) Giving Derivatives of Pyrane, Chromene, Fluorene, Phenanthrene and Dibenzo[7]annulene by Ruthenium Complexes

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

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