Synthesis of Indenes by the Palladium-Catalyzed Carboannulation of Internal Alkynes

Zhang, Dao Hua; Yum, Eul Kgun; Liu, Zhijian; Larock, Richard C.

doi:10.1021/ol051907a

Cited by 64 publications

(37 citation statements)

References 29 publications

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“…When ethyl 4‐iodobenzoate ( 1 a ) was allowed to react with 1‐phenylpropyne ( 2 b ) and aryne precursor 3 a , only one isomeric phenanthrene was obtained in 56 % yield (Table 2, entry 12). Similar regioselectivity for this alkyne has been observed in our earlier work 14. Ethyl 3‐phenylpropiolate ( 2 c ) afforded two isomers, 4 n and 4 o , in a 1:6 ratio (Table 2, entry 13).…”

Section: Optimization Of the Palladium‐catalyzed Three‐component Crossupporting

confidence: 83%

Palladium‐Catalyzed, Sequential, Three‐Component Cross‐Coupling of Aryl Halides, Alkynes, and Arynes

2007

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Alkynes have been frequently used as substrates for palladium-catalyzed carbopalladation by functionally substituted aryl and vinylic halides.[1] Aryl halides have also been treated with alkynes in the presence of a palladium catalyst to generate naphthalenes.[2] Arynes [3] are very reactive substrates compared to ordinary alkynes. Although there are a number of examples of stoichiometric transition-metal aryne complexes being employed creatively in organic synthesis, [4] arynes [5] have only recently been reported to undergo palladium-catalyzed conversion. Thus, the cyclotrimerization of arynes [6] and the co-cyclotrimerization of arynes with alkynes [7] are catalyzed by palladium. Yamamoto and coworkers have established that p-allylpalladium species are very effective for the intermolecular carbopalladation of arynes and can be employed in a three-component coupling with alkynes to produce naphthalenes.[8] Until the recent demonstration that an aryne can react with benzyl bromide in the presence of a palladium catalyst and undergo a subsequent Heck reaction, [9] all examples of the carbopalladation of arynes have involved very stable p-allylpalladium intermediates. [8, 10] Recently, we reported that aryl and vinylic halides can be employed in the catalytic carbopalladation of arynes.[11] Our experience in aryne and alkyne chemistry led us to consider the possibility of using palladium to catalyze the stepwise carbopalladation of alkynes and arynes using aryl halides. Herein, we wish to report preliminary results on the palladium-catalyzed, three-component, sequential intermolecular coupling of aryl halides, alkynes, and arynes [Eq. (1); TMS = trimethylsilyl, OTf = OS(O) 2 CF 3 ].We first allowed ethyl 4-iodobenzoate (1 a) to react with 2.0 equiv of diphenyl acetylene (2 a), 2.0 equiv of the silylaryl triflate 3 a, 5 mol % of [Pd(dba) 2 ] (dba = dibenzylidenacetone), 5 mol % of 1,1'-bis(diphenylphosphino)ferrocene (dppf), and 3.0 equiv of CsF in 2.0 mL of MeCN and 2.0 mL of toluene at 90 8C for 24 h. Surprisingly, we obtained only product 4 a in a 22 % yield, and compound 5 a was not detected [Eq.

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Section: Optimization Of the Palladium‐catalyzed Three‐component Crossupporting

confidence: 83%

Palladium‐Catalyzed, Sequential, Three‐Component Cross‐Coupling of Aryl Halides, Alkynes, and Arynes

2007

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“…(46)) [476]. Indenes were formed by a palladium-catalyzed reaction of internal alkynes and (2-halophenyl)-substituted activated methylene compounds [477]. Oxidative addition to 2-iodo-4-(phenylchalcogenyl)-1-butenes followed alkyne insertion and Sonogashira termination was reported (Eq.…”

Section: Carbon-carbon Bond Formation Via Insertion Of Alkynesmentioning

confidence: 99%

Transition metals in organic synthesis: Highlights for the year 2005

Söderberg

2008

Coordination Chemistry Reviews

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“…The carbo‐ and heterocyclic compounds constitutes an important class due to their presence in a large number of drug molecules, which acquire a remarkable pharmaceutical activity . For instance, indene skeleton with an exo ‐alkylidene moiety is embedded in Sulindac ( 1 ), which is a non‐steroidal anti‐inflammatory drug, Dimethindene ( 2 ), an oral antihistamine agent, and Donepezil ( 3 ), an anti‐Alzheimer drug (Figure ) .…”

Section: Figurementioning

confidence: 99%

Regioselective 5‐endo‐dig Electrophilic Iodocyclization of Enediynes: A Convenient Route to Iodo‐substituted Indenes and Cyclopenta‐Fused Arenes

Saunthwal

Danodia

Patel

et al. 2016

Chemistry An Asian Journal

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An efficient iodine-mediated regioselective tandem approach for the synthesis of symmetric and asymmetric iodo-substituted indenes and stereoselective cyclopenta [b]pyridine/thiophenes from easily accessible enediynes that proceeds by in situ formation of an iodonium intermediate followed by a regioselective 5-endo-dig cyclization has been described. The intramolecular electrophilic iodocyclization was selectively triggered by a distribution of electronic density along the alkyne bond. Subsequently, the iodo-substituted indenes were diversified by employing palladium-catalyzed cross-coupling reactions and the coupled products were further confirmed by X-ray crystallographic studies.

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Synthesis of Indenes by the Palladium-Catalyzed Carboannulation of Internal Alkynes

Cited by 64 publications

References 29 publications

Palladium‐Catalyzed, Sequential, Three‐Component Cross‐Coupling of Aryl Halides, Alkynes, and Arynes

Palladium‐Catalyzed, Sequential, Three‐Component Cross‐Coupling of Aryl Halides, Alkynes, and Arynes

Transition metals in organic synthesis: Highlights for the year 2005

Regioselective 5‐endo‐dig Electrophilic Iodocyclization of Enediynes: A Convenient Route to Iodo‐substituted Indenes and Cyclopenta‐Fused Arenes

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