Synthesis of 2-aminobenzoxazoles from elemental sulfur mediated cyclization of 2-aminophenols and aryl isothiocyanates

Tran, Danh T.; Huynh, Tan N.; Nguyen, Phuc H.; Phan, Nam T. S.; Nguyen, Tung T.

doi:10.1016/j.tetlet.2023.154510

Cited by 4 publications

(3 citation statements)

References 20 publications

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“…We then turned our attention to extending the scope of 2-nitrophenols, as this is the major improvement compared with previous methods. 5 The results are shown in Scheme 3 . To our expectation, an array of 2-aminobenzoxazoles bearing useful functionalities has been successfully isolated.…”

Section: Resultsmentioning

confidence: 99%

“…These molecules were hardly obtained from methods starting with 2-aminophenols. 5 2-Aminobenzoxazole derived from 4-hydroxy-3-nitropyridine was obtained in moderate yield (3oa), somewhat indicating that heteroaryl-based 2-nitrophenols were also competent substrates. Attempt to use 2-nitroaniline to couple with phenyl isothiocyanate was not successful at this moment.…”

Section: Resultsmentioning

confidence: 99%

“… 3 Given the importance of the aforesaid N,O-heterocycles in bio-related studies, 4 substantial studies have been devoted to extension of substrate scope. 5 Notably, 2-aminophenols attached with varied functionalities are neither commercially available nor viably prepared. Herein we would like to report a method for synthesis of 2-aminobenzoxazoles from annulation of 2-nitrophenols and aryl isothiocyanates.…”

Section: Introductionmentioning

confidence: 99%

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Utilization of 2-nitrophenols in annulations with aryl isothiocyanates towards the synthesis of 2-aminobenzoxazoles

et al. 2023

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Utilization of 2-nitrophenols in annulations with aryl isothiocyanates towards the synthesis of 2-aminobenzoxazoles

et al. 2023

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HFIP‐Mediated Cyclodesulfurization Approach for the Synthesis of 2‐Aminobenzoxazole and 2‐Aminobenzothiazole Derivatives

Kant,

Patel,

Banerjee

et al. 2024

Asian J Org Chem

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A straightforward strategy for the synthesis of pharmaceutically active 2‐aminobenzoxazoles and 2‐aminobenzothiazoles is described by using 2‐aminophenols, 2‐aminothiophenols, and functionalized phenylisothiocyanates as the model substrates. The developed method proceeds through the HFIP‐promoted cyclodesulfurization process which allows for the efficient synthesis of these scaffolds at 60 °C of reaction temperature without the addition of a transition metal‐catalyst or hazardous solvents with excellent yields (up to 92%) of product formation. This process involves HFIP‐mediated hydrogen bonding interactions with the hydroxyl and thiol moieties, leading to bond breaking and formation during the reaction, resulting in the compounds of interest and the in situ release of H2S gas.

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Elemental Sulfur Promoted Cyclization of Aryl Hydrazones and Aryl Isothiocyanates Yielding 2-Imino-1,3,4-thiadiazoles

Huynh,

Ong,

Dinh

et al. 2024

J. Org. Chem.

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We report a method for using elemental sulfur to facilitate the cyclization of aryl hydrazones and aryl isothiocyanates, affording biorelated 2-imino-1,3,4-thiadiazoles. Reactions progressed in the presence of elemental sulfur, N-methylmorpholine base, and DMSO solvent, while were tolerant of a wide range of functionalities including halogen, nitro, cyano, methylsulfonyl, and heterocyclic groups. The method appears to offer a general pathway for using simple, cheap, and stable reagents to afford triaryl-substituted 2-imino-1,3,4-thiadiazoles under relatively mild conditions.

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Synthesis of 2-aminobenzoxazoles from elemental sulfur mediated cyclization of 2-aminophenols and aryl isothiocyanates

Cited by 4 publications

References 20 publications

Utilization of 2-nitrophenols in annulations with aryl isothiocyanates towards the synthesis of 2-aminobenzoxazoles

Utilization of 2-nitrophenols in annulations with aryl isothiocyanates towards the synthesis of 2-aminobenzoxazoles

HFIP‐Mediated Cyclodesulfurization Approach for the Synthesis of 2‐Aminobenzoxazole and 2‐Aminobenzothiazole Derivatives

Elemental Sulfur Promoted Cyclization of Aryl Hydrazones and Aryl Isothiocyanates Yielding 2-Imino-1,3,4-thiadiazoles

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