Access to C4-arylated benzoxazoles from 2-amidophenol through C–H activation

Sahoo, K. K.; Pradhan, Priyanka; Panda, Niranjan

doi:10.1039/d0ob00061b

Cited by 13 publications

(7 citation statements)

References 51 publications

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“…The benzoxazole core is an important pharmacophore in drug discovery. The product ortho-acetamido phenol 3a was subjected to palladiumcatalyzed conditions 19 in the presence of aryl iodide delivered benzoxazole derivative 6 in 76% yield (Scheme 4c).…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Breaking the Monotony: Cobalt and Maleimide as an Entrant to the Olefin-Mediated Ortho C–H Functionalization

et al. 2022

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A catalytic system is discovered for the intramolecular C–H amidation of N-phenoxy acetamide derivatives. Herein, a cobalt catalyst has been employed for the olefin-mediated ortho C–H functionalization. Moreover, a monocyclic olefin, maleimide, has been used as a transient mediator instead of well-established bicyclic norbornenes. Maleimide promotes a Co(III) intermediate to undergo oxidative addition into the O–N bond to form a Co(V) nitrene species and subsequently directs nitrene addition to the ortho position. Mechanistic study and density functional theory (DFT) study support the proposed mechanism. The products derived from this methodology have been demonstrated as a ligand in the C–H olefination reaction. Furthermore, the synthetic utility of this methodology was demonstrated via the ortho-amidation of estrone.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Breaking the Monotony: Cobalt and Maleimide as an Entrant to the Olefin-Mediated Ortho C–H Functionalization

et al. 2022

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“…Recently, the Panda’s group developed a method for the synthesis of 4-arylbenzo[ d ]oxazoles 15 based on palladium-catalyzed cross-coupling of N -(2-hydroxyaryl)amides 14 with aryl iodides in the presence of silver oxide in methanesulfonic acid. 16 4-Phenylbenzo[ d ]oxazoles 15b – k were prepared using the described procedure (Scheme 3 ).…”

Section: Table 1 Optimization Of Conditions For the Rea...mentioning

confidence: 99%

“…The preparation of benzo[ d ]oxazoles 15b – k and 2-aminobiphenyl-3-ol ( 16 ) was carried out in accordance with the previously described procedure. 16…”

mentioning

confidence: 99%

“…14b Cyclic carbamate 15l was synthesized in 74% yield by heating compound 16 with urea in DMF. 17 The reaction of 2-aminobiphenyl-3-ol (16) with acetyl isothiocyanate 18 afforded acetylthiourea 17. The latter underwent intramolecular cyclization by the action of an aqueous solution of hydrogen peroxide followed by hydrolysis of the acetamide group to form 4-phenylbenzo [d]oxazol-2-amine (15m) in 53% yield (Scheme 4).…”

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confidence: 99%

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A Rearrangement of 4-Phenylbenzo[d]oxazoles to Phenanthridin-4-ols

Fisyuk,

Shatsauskas,

Keyn

et al. 2023

Synthesis

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“…Benzoxazole core is an important pharmacophore in drug discovery. The product ortho-acetamido phenol 3a subjected to palladium catalyzed condition 20 in the presence of aryl iodide delivered benzoxazole derivative 6 in 76% yield (Scheme 3c). Scheme 3.…”

Section: Synthetic Utilitymentioning

confidence: 99%

Breaking The Monotony: Cobalt and Maleimide as a New Entrant to the Catellani Reaction

Nanda

Banjare

Prasad

et al. 2022

Preprint

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A catalytic system was discovered for the intramolecular C-H amidation of N-phenoxy acetamide derivatives. For the first time, a cobalt catalyst was employed for the Catellani reaction. Additionally, a monocyclic olefin, maleimide, was used as a transient mediator in place of bicyclic norbornenes. Maleimide promotes a Co(III) intermediate to undergo oxidative addition into the O–N bond to form a Co(V) nitrene species and subsequently directs nitrene addition to the ortho position. A plausible mechanism for the transformation is proposed, supported by experimental and density functional theory (DFT) computational studies. Further, the synthetic utility of this methodology was demonstrated via the ortho-amidation of estrone.

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Access to C4-arylated benzoxazoles from 2-amidophenol through C–H activation

Abstract: A Pd-catalyzed aerobic approach to access C4-aryl benzoxazoles by tandem C–H ortho-arylation and acid-mediated annulation of 2-amidophenol has been presented.

Cited by 13 publications

References 51 publications

Breaking the Monotony: Cobalt and Maleimide as an Entrant to the Olefin-Mediated Ortho C–H Functionalization

Breaking the Monotony: Cobalt and Maleimide as an Entrant to the Olefin-Mediated Ortho C–H Functionalization

A Rearrangement of 4-Phenylbenzo[d]oxazoles to Phenanthridin-4-ols

Breaking The Monotony: Cobalt and Maleimide as a New Entrant to the Catellani Reaction

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