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Cu(II)/Vasicine Promoted Intramolecular C-O Formation: Synthesis of Benzoxazoles in EtOH

[ Vol. 18 , Issue. 3 ]

Author(s):

Minxin Li, Meiling Li, Yanling Tang, Yun Sun*, Lu Qu and Zewei Mao*   Pages 310 - 315 ( 6 )

Abstract:


Aims and Objectives: Benzoxazoles are valuable bicyclic aromatic compounds; the construction of benzoxazoles via C-O cross-coupling reactions has attracted more and more attention.

Materials and Methods: The best condition of C-O bond formation from o-haloanilides was carried out, taking Cu(OTf)2 (5 mol%) and vasicine (10 mol%) as the catalysts in EtOH in the presence of K2CO3 (2 eq.) for 12 h at 90°C.

Results: A series of 2-substituted benzoxazoles have been prepared in high yields from 2-bromoanilides and 2- iodioanilides under mild conditions.

Conclusion: We have developed an efficient Cu-vasicine catalytic system for intramolecular C-O bond formation. This strategy is applicable to the synthesis of a wide variety of 2-substituted benzoxazoles by intramolecular O-arylation of o-haloanilides.

Keywords:

Cu(II)-vasicine, intramolecular O-arylation, o-haloanilides, benzoxazoles, EtOH, cross-coupling reactions.

Affiliation:

College of Pharmaceutical Science, Yunnan University of Chinese Medicine, Kunming 650500, College of Pharmaceutical Science, Yunnan University of Chinese Medicine, Kunming 650500, College of Pharmaceutical Science, Yunnan University of Chinese Medicine, Kunming 650500, College of Pharmaceutical Science, Yunnan University of Chinese Medicine, Kunming 650500, College of Pharmaceutical Science, Yunnan University of Chinese Medicine, Kunming 650500, College of Pharmaceutical Science, Yunnan University of Chinese Medicine, Kunming 650500

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