Base promoted coupling of α-ketoacids and 2-substituted aromatic amines: Green synthesis of diverse benzoxazoles, benzothiazoles, quinoxalinones and benzoxazinones and its practical application

Synthesis of 2-aryl substituted benzoxazoles, benzothiazoles, and quinoxalinones via decarboxylative coupling of α-keto acids with 2-aminophenol, 2-aminothiophenol, and OPD (o-phenylenediamine), using K2CO3 as a base in water at room temperature, and as well as solvent-free grinding and the synthesi...

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Bibliographic Details
Published in:Synthetic communications 2024-01, Vol.54 (1), p.50-65
Main Authors: Mathavan, Sivagami, Ramesh, Subburethinam, Yamajala, Rajesh B. R. D.
Format: Article
Language:English
Subjects:
Amines
Aminophenol
Coupling
Functional groups
Oxazole
Phenylenediamine
Room temperature
Substitutes
Synthesis
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Summary:Synthesis of 2-aryl substituted benzoxazoles, benzothiazoles, and quinoxalinones via decarboxylative coupling of α-keto acids with 2-aminophenol, 2-aminothiophenol, and OPD (o-phenylenediamine), using K2CO3 as a base in water at room temperature, and as well as solvent-free grinding and the synthesis of benzoxazinones from the reaction of α-keto acids with 2-aminophenol at 60 °C have been reported. Both the protocols afforded a wide range of desired products with excellent functional group tolerance in yields of 87–99%. The major advantages of these approaches are catalyst-free protocol, short reaction times, straightforward workup, and chromatography-free processing of the products. Additionally, to test the translational demand of this methodology, the synthesis of 2-(3,5-dichlorophenyl)-6-methylbenzo[d]oxazole was carried out which is a key structure of tafamidis, a commercially available drug.
ISSN:0039-7911
1532-2432
DOI:10.1080/00397911.2023.2280599