Cobalt-Promoted Dimerization of Aminoquinoline Benzamides

Grigorjeva, Liene; Daugulis, Olafs

doi:10.1021/acs.orglett.5b00155

Cited by 137 publications

(52 citation statements)

References 66 publications

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“…[1,2] Although the use of noble metals,i ncluding Pd, Rh, Ru, and Ir,h as been dominating the field of C À Ha ctivation, [3] cobalt-catalyzed C À Hactivation reactions [4,5] have also received much interest because cobalt is earth-abundant and therefore less expensive than noble metals.M oreover,o wing to its unique reactivity and functional-group tolerance,the use of cobalt catalysts for C À Hactivation provides acomplementary method to noblemetal catalysis.…”

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confidence: 99%

Diastereoselective [3+2] Annulation of Aromatic/Vinylic Amides with Bicyclic Alkenes through Cobalt‐Catalyzed C−H Activation and Intramolecular Nucleophilic Addition

2016

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A highly diastereoselective method for the synthesis of dihydroepoxybenzofluorenone derivatives from aromatic/vinylic amides and bicyclic alkenes is described. This new transformation proceeds through cobalt-catalyzed C-H activation and intramolecular nucleophilic addition to the amide functional group. Transition-metal-catalyzed C-H activation reactions of secondary amides with alkenes usually lead to [4+2] or [4+1] annulation; to the best of our knowledge, this is the first time that a [3+2] cycloaddition is described in this context. The reaction proceeds under mild conditions and tolerates a wide range of functional groups. Mechanistic studies imply that the C-H bond cleavage may be the rate-limiting step.

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Diastereoselective [3+2] Annulation of Aromatic/Vinylic Amides with Bicyclic Alkenes through Cobalt‐Catalyzed C−H Activation and Intramolecular Nucleophilic Addition

2016

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“…In this transformation, at ransitionmetal catalyzedc ross-coupling reactiono ft wo prefunctionalized materials has been well documented. [8] However,i nt heset wo cases, either Cu or Co salt was stoichiometrically required. [2] Recently, transition-metal-catalyzed homocoupling of CÀH/CÀHb onds has been developeda sa ne fficient and straightforward strategy for constructing biaryl skeletons.…”

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“…[3] This approach does not requirep refunctionalized startingm aterials, which reduces the synthetic steps and amount of byproducts. Prior to our optimization of the reaction conditions for this reaction, the research group of Daugulis [8] publishedt heir study on the same reaction. Yu and co-workersreported Cu II -mediated dimerization of 2-arylpyridines.…”

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“…[2] Recently, transition-metal-catalyzed homocoupling of CÀH/CÀHb onds has been developeda sa ne fficient and straightforward strategy for constructing biaryl skeletons. [8] However,i nt heset wo cases, either Cu or Co salt was stoichiometrically required. 2-Arylpyridines, phenylacetamides, anda ryloxazolines were proven to be effective substrates to undergo the oxidative homocoupling reaction for construction of the biaryl compounds using Pd, [4] Ru, [5] and Ni [6] catalysis.…”

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“…(1)]. Prior to our optimization of the reaction conditions for this reaction, the research group of Daugulis [8] publishedt heir study on the same reaction. The difference between co-amide complexes 3 and 4 is the different orientation of the acetylacetone anion group that is attached to the cobalt metal.…”

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Cobalt‐Catalyzed Oxidative Dimerization of 2‐Phenylpyridine Derivatives

Xie

Sun

et al. 2016

Asian J Org Chem

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The oxidative dimerizationo f2 -phenylpyridine derivatives using cobalt catalysis is reported. Three types of reaction conditions were developed with different loadings of cobalt catalyst. Cross couplingo ft wo different 2arylpyridines using cobalt catalysis proceeded with modest yields and selectivity.The biaryl moiety is one of the most important privileged structures in medicinal chemistry and is prevalent in al arge number of pharmaceuticals and biologically active molecules. [1] Many methods have been developedt op repare aryl-aryl or aryl-heteroaryl compounds. In this transformation, at ransitionmetal catalyzedc ross-coupling reactiono ft wo prefunctionalized materials has been well documented. [1] The low valent cobalt complexes, usually in situ generated, exhibit high reactivity and selectivity in the cross-coupling reaction. [2] Recently, transition-metal-catalyzed homocoupling of CÀH/CÀHb onds has been developeda sa ne fficient and straightforward strategy for constructing biaryl skeletons. [3] This approach does not requirep refunctionalized startingm aterials, which reduces the synthetic steps and amount of byproducts. 2-Arylpyridines, phenylacetamides, anda ryloxazolines were proven to be effective substrates to undergo the oxidative homocoupling reaction for construction of the biaryl compounds using Pd, [4] Ru, [5] and Ni [6] catalysis. Yu and co-workersreported Cu II -mediated dimerization of 2-arylpyridines. [7] The research group of Daugulis described the Co III -promoted dimerization of aminoquinoline benzamides. [8] However,i nt heset wo cases, either Cu or Co salt was stoichiometrically required. Herein, we report the oxidative homocoupling of 2-phenylpyridinesw ith am ore abundant and cheaper cobalt catalyst using PhI(OAc) 2 and O 2 as cooxidants.During our recent studies on cobalt-mediated ortho-CÀH functionalization of carboxamide 1,w eo bserved the formation of dimerization product 2 and isolated two types of cobaltamide complexes 3 and 4 [9] [Eq. (1)].X -ray single-crystald iffraction established the structurest ob eb iaryl-linked diamide compounds complexed with Co III metal anda na cetylacetone anion as the ligand. The difference between co-amide complexes 3 and 4 is the different orientation of the acetylacetone anion group that is attached to the cobalt metal. Prior to our optimization of the reaction conditions for this reaction, the research group of Daugulis [8] publishedt heir study on the same reaction. Therefore, we focused our attention on the dimerization of other types of substrates using cobalt catalysis. As 2phenylpyridines werew ell used as substrates in the cobalt-catalyzed coupling reaction, [10] we envisionedt hat 2-phenylpyridines could undergo an oxidativeh omocoupling reaction via cobalt catalysis under the appropriate conditions.The investigation of the oxidative homocoupling reaction employed 2-phenylpyridine 5a as the substrate. The initial reactions conditions included Co(OAc) 2 ·4 H 2 O( 10 mol %) and PhI(OAc) 2 (2 equiv) as an oxidanti nA cOH under reflux, ...

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