A straightforward synthesis of N-monosubstituted α-keto amides via aerobic benzylic oxidation of amides

Shao, Jun Peng; Huang, Xiaomei; Wang, Siyuan; Liu, Bingxin; Xu, Bo

doi:10.1016/j.tet.2011.11.005

Cited by 38 publications

(25 citation statements)

References 80 publications

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“…On the basis of these investigations, we proposed a plausible mechanism for this transformation as depicted in Scheme . Initially, 1a was aerobically oxidized to α‐keto amide 6 ,17 which gave the isatin product 5c after a copper‐catalyzed intramolecular amination reaction. Subsequently, the intramoleular nucleophilic attack of pyridyl to ketone afforded a tricyclic zwitterionic intermediate A .…”

Section: Methodsmentioning

confidence: 99%

“…[17] The absence of ligand also led to a diminished yield (entry 24). Trace amounts of product was detected when the reaction was conducted under a nitrogen atmosphere (entry 25) or in the absence of CuI (entry 26), which implied that atmospheric oxygen and copper salt are crucial for this transformation.…”

Section: Entrymentioning

confidence: 99%

“…To our surprise, the reaction afforded an unexpected product -6-methyl-11H-pyridoA C H T U N G T R E N N U N G [2,1-b]quinazolin-11-one (2b) -in 58% yield (Table 1, entry 1). An extensive screening concerning copper sources (entries 2-5), bases (entries 6-9), ligands (entries 10-16), additives (entries [17][18][19] and solvents (entries [20][21][22] revealed that the use of CuI and 1,10-Phen as catalyst, KOAc as base and TBAB as additive in DMF at 100 8C under air was the best choice and resulted in 2b in 87% yield (entry 22). It is worth noting that decreased yields were obtained in the absence of TBAB (entry 23), which was supposed to act as a phasetransfer catalyst for the copper ions by transmitting them in the form of complexes to the organic phase where the reaction takes place [16] or be involved in the benzylic oxidation reaction by adjusting the soluScheme 1.…”

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confidence: 99%

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Copper‐Catalyzed Aerobic Oxidative Annulation and Carbon‐Carbon Bond Cleavage of Arylacetamides: Domino Synthesis of Fused Quinazolinones

Sun,

Tan,

Yang

et al. 2014

Adv Synth Catal

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An efficient copper-catalyzed tandem aerobic oxidative annulation and carbon-carbon bond cleavage reaction was developed from easily accessible arylacetamides, which provides a direct approach for the domino synthesis of a vast array of tricyclic or tetracyclic fused quinazolinone alkaloid structures. A plausible reaction mechanism is proposed involving an aerobic benzylic oxidation/ cyclization/decarbonylation cascade.

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Section: Methodsmentioning

confidence: 99%

Section: Entrymentioning

confidence: 99%

mentioning

confidence: 99%

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Copper‐Catalyzed Aerobic Oxidative Annulation and Carbon‐Carbon Bond Cleavage of Arylacetamides: Domino Synthesis of Fused Quinazolinones

Sun,

Tan,

Yang

et al. 2014

Adv Synth Catal

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“…The detailed mechanism requires further study, however, based on the available data we have and the base-mediated aerobic oxidation involving deprotonation at the carbonyl position described 25 26 27 , a possible mechanism of the oxidation is proposed in Fig. 3 .…”

Section: Resultsmentioning

confidence: 98%

Activated carbon for aerobic oxidation: Benign approach toward 2-benzoylbenzimidazoles and 2-benzoylbenzoxazoles synthesis

Bao

Liu

et al. 2015

Sci Rep

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A general strategy involving a novel and highly efficient aerobic benzylic oxidation promoted by cheap, reusable activated carbon in water is developed. Application of this method has been demonstrated in the benign synthesis of bioactive 2-benzoylbenzimidazoles and 2-benzoylbenzoxazoles derivatives. Furthermore, the activated carbon catalyst could be recovered and reused at least three times without significantly losing its activity. Preliminary research suggests that the oxidation mechanism may involve intermediate hydroperoxidation and that a portion of the final carbonyl product is obtained through a secondary benzylic alcohol intermediate. Finally, theoretical calculations reveal that the oxidation yield is closely associated with the electric density at the benzylic position of the substrate.

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“…2‐(4‐Methoxyphenyl)‐2‐oxo‐ N ‐phenylacetamide (2g): 1l Yield 120.0 mg (94 %); yellow solid. 1 H NMR (400 MHz, CDCl 3 ): δ = 9.01 (br.…”

Section: Methodsmentioning

confidence: 99%

α‐Carbonylimine to α‐Carbonylamide: An Efficient Oxidative Amidation Approach

et al. 2015

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Our interest in generating amide bonds by employing the activated C=N system has led to the development of an efficient oxidative amidation reaction between 2‐oxoaldehyde and weak nucleophilic amines (anilines, benzamides and sulfonamides). Mechanistic studies support the involvement of α‐carbonylimine (–CO–C=N–) based compounds or intermediates as a central feature of the reaction, in which an adjacent CO moiety enhances the electrophilicity of the C=N system, which favors attack of the oxidant (TBHP or SeO2), thereby resulting in the generation of the desired products in good yields. The direct oxidative coupling of 2‐oxoaldehydes and weak nucleophilic amines has been accomplished through either MgSO4–TBHP–pyridine/CuBr, or SeO2·pyridine promoted methods. In the current study, SeO2·pyridine emerged as a versatile reagent with which to promote initial α‐carbonylimine formation between 2‐oxoaldehyde and weak nucleophilic amine, and subsequent oxidation to the corresponding α‐carbonylamide. The reported methodology constitutes one of the few reports of the synthesis of α‐ketoamides from anilines, perhaps the second report for the generation of α‐ketoimides, and the first report of the generation of 2‐oxoamides with sulfonamides.

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A straightforward synthesis of N-monosubstituted α-keto amides via aerobic benzylic oxidation of amides

Cited by 38 publications

References 80 publications

Copper‐Catalyzed Aerobic Oxidative Annulation and Carbon‐Carbon Bond Cleavage of Arylacetamides: Domino Synthesis of Fused Quinazolinones

Copper‐Catalyzed Aerobic Oxidative Annulation and Carbon‐Carbon Bond Cleavage of Arylacetamides: Domino Synthesis of Fused Quinazolinones

Activated carbon for aerobic oxidation: Benign approach toward 2-benzoylbenzimidazoles and 2-benzoylbenzoxazoles synthesis

α‐Carbonylimine to α‐Carbonylamide: An Efficient Oxidative Amidation Approach

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