A Palladium‐Catalyzed Oxidative Cycloaromatization of Biaryls with Alkynes Using Molecular Oxygen as the Oxidant

Shi, Zhuangzhi; Ding, Shengtao; Cui, Yuxin; Jiao, Ning

doi:10.1002/anie.200903975

Cited by 257 publications

(93 citation statements)

References 70 publications

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“…10 Following this pioneering work, Jiao developed a Pd-catalyzed cycloaromatization of 2-and 3-arylindoles with internal alkynes in the presence of molecular oxygen. 11 Chen developed an efficient construction of aza-fused polycyclic quinolines from N-arylazoles and alkynes under With the optimized reaction conditions in hand, we then explored the scope of this reaction.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Naphtho[1′,2′:4,5]imidazo[1,2-a]pyridines and Imidazo[5,1,2-cd]indolizines Through Pd-Catalyzed Cycloaromatization of 2-Phenylimidazo[1,2-a]pyridines with Alkynes

Zhang

Fan

2015

J. Org. Chem.

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In this paper, palladium-catalyzed oxidative cycloaromatization of 2-phenylimidazo[1,2-a]pyridine (PIP) with internal alkyne is studied. From this reaction, two classes of fused N-heterocycle, naphtho[1',2':4,5]imidazo[1,2-a]pyridine (NIP) and imidazo[5,1,2-cd]indolizine (IID), were formed through dehydrogenative coupling featured with cleavage of the C-H bonds located on different moiety of the PIP substrates. Moreover, when 5-methyl-2-phenylimidazo [1,2-a]pyridine or 2-mesitylimidazo[1,2-a]pyridine was used, either NIP or IID could be obtained as an exclusive product with good efficiency. Intriguingly, Pd(II) showed different action mode in promoting this reaction compared with Rh(III) and led to the formation of NIP with reversed regio-selectivity for the reaction of asymmetrical alkyne.

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Section: Introductionmentioning

confidence: 99%

Synthesis of Naphtho[1′,2′:4,5]imidazo[1,2-a]pyridines and Imidazo[5,1,2-cd]indolizines Through Pd-Catalyzed Cycloaromatization of 2-Phenylimidazo[1,2-a]pyridines with Alkynes

Zhang

Fan

2015

J. Org. Chem.

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“…62 The process involves the cleavage of two C-H bonds and lead to carbocyclic adducts. It has been proposed that the reaction proceeds through an initial electrophilic aromatic palladation followed by migratory insertion of the alkyne to give an alkenyl palladium(II) intermediate.…”

Section: (4+2) Annulationsmentioning

confidence: 99%

Metal‐Catalyzed Annulations through Activation and Cleavage of C−H Bonds

2016

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Abstract:The exponential increase in the number of catalytic transformations that involve a metal-promoted activation of hitherto considered inert C-H bonds is promoting a paradigmatic change in the field of synthetic chemistry. While most reactions involving C-H activations consist of simple functionalizations or additions, recent years have witnessed a boost on related transformations that can be formally considered as cycloaddition processes. These transformations are particularly appealing from a synthetic perspective because they allow the conversion of readily available substrates into highly valuable cyclic products in a rapid and sustainable manner. In many cases, these annulations involve the formation of metallacyclic intermediates that resemble those proposed for standard metalcatalyzed cycloadditions of unsaturated precursors.

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“…Some representative previous reactions are shown in Scheme 24. Pd-and Rh-catalysts are effective for aromatization between biaryls (73 and 75) and alkynes, 114,115 giving the aromatization compounds 74 and 76, respectively. Also, the catalysts are useful for the annulation between 77 and diphenylacetylene, and between 79 and alkynes, to give the annulation products 78 and 80, respectively.…”

Section: Scheme 18mentioning

confidence: 99%

π-Conjugated carbocycles and heterocycles via annulation through C-H and X-Y activation across CC triple bonds

Yamamoto¹,

Almansour²,

Arumugam³

et al. 2015

Arkivoc

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AbstractIn this account our own research results on the methods of annulation and hetero-annulation across alkynes are summarized, especially emphasizing the annulation and hetero-annulation through C-H and X-Y activation. A wide range of quinolines, isoquinolines, indoles, benzofurans, indenes, and benzothiophenes can be synthesized via mono-annulation of ortho-alkynylaryl derivatives using transition metal catalysts and/or iodine reagents. Benzocarbazoles, benzonaphthothiophenes, and indenochromenes can be synthesized via cascade annulation of 1,2-dialkynyl substituted benzene derivatives. Palladium-catalyzed crossover annulation of compounds bearing two vicinal CC triple bonds attached to an unsaturated ring gives dibenzopentalenes through C-H activation, and intramolecular cross annulation of bisbiarylalkynes affords 9,9-bifluorenylidenes via dual C-H activation.

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A Palladium‐Catalyzed Oxidative Cycloaromatization of Biaryls with Alkynes Using Molecular Oxygen as the Oxidant

Cited by 257 publications

References 70 publications

Synthesis of Naphtho[1′,2′:4,5]imidazo[1,2-a]pyridines and Imidazo[5,1,2-cd]indolizines Through Pd-Catalyzed Cycloaromatization of 2-Phenylimidazo[1,2-a]pyridines with Alkynes

Synthesis of Naphtho[1′,2′:4,5]imidazo[1,2-a]pyridines and Imidazo[5,1,2-cd]indolizines Through Pd-Catalyzed Cycloaromatization of 2-Phenylimidazo[1,2-a]pyridines with Alkynes

Metal‐Catalyzed Annulations through Activation and Cleavage of C−H Bonds

π-Conjugated carbocycles and heterocycles via annulation through C-H and X-Y activation across CC triple bonds

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