Direct and practical synthesis of 2-arylbenzoxazoles promoted by activated carbon

Organic Letters

Volumn 5, Issue 20, 2003, Pages 3713-3715

  Kawashita, Yuka ^a   Nakamichi, Natsuki ^a   Kawabata, Hirotoshi ^a   Hayashi, Masahiko ^a  

^a KOBE UNIVERSITY   (Japan)

Author keywords

[No Author keywords available]

Indexed keywords

BENZOXAZOLE DERIVATIVE; CARBON;

ARTICLE; ATMOSPHERE; SUBSTITUTION REACTION; SYNTHESIS;

EID: 0142106411     PISSN: 15237060     EISSN: None     Source Type: Journal    
DOI: 10.1021/ol035393w     Document Type: Article

References (20)

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16. Typical Procedure (see entry 1 in Table 2). A mixture of 2-aminophenol (873 mg, 8 mmol), benzaldehyde (849 mg, 8 mmol), and Darco KB (1 g) in xylene (15 mL) was placed in a 100 mL three-necked flask under an oxygen atmosphere and stirred at 120°C for 4 h. The reaction mixture was then filtered using Celite. After the filtrate was concentrated, the product was isolated by silica gel column chromatography to give a pale yellow crystalline solid 1.2 g (78%). When 0.2 g of activated carbon (Darco KB) was used in the above reaction (in the same substrate scale), a longer reaction time was required (18 h, 85%).
17. Even with Darco G-60, the product could be obtained in 96% yield with a longer reaction time (27 h).
18. (a) Singh, M. P.; Sasmal, S.; Lu, W.; Chatterjee, M. N. Synthesis 2000, 1380-1390.
19. (b) Beaulieu, P. L.; Haché, B.; Moos, E. Synthesis 2003, 1521-1530.
20. Present activated carbon-oxygen (or air) system was also applied to the oxidative aromatization of 1,3,5-trisubstituted pyrazolines and Hantzsch 1,4-dihydropyridines. The details will be reported soon.