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Microwave-Assisted Improved Regioselective Synthesis of 12H-Benzopyrano[3,2-c][1]benzopyran-5-ones by Radical Cyclisation
Joint Authors
Basu, Pradipta Kumar
Ghosh, Amrita
Source
Organic Chemistry International
Issue
Vol. 2011, Issue 2011 (31 Dec. 2011), pp.1-6, 6 p.
Publisher
Hindawi Publishing Corporation
Publication Date
2011-09-15
Country of Publication
Egypt
No. of Pages
6
Main Subjects
Abstract EN
Two new effective methodologies have been adopted for the preparation of 4-(2′-bromobenzyloxy)benzopyran-7-ones 3(a–h).
In the first methodology, 4-hydroxy[1]benzopyran-2-ones 1(a–d) was alkylated with 2-bromobenzyl bromide 2a or 2-bromo-5-methoxy benzyl bromide 2b under phase transfer catalysis condition using lithium hydroxide/tetrabutyl ammonium bromide in N,N-dimethylformamide at 40–50°C and in the second method the microwave irradiation protocol has been exploited by simply mixing of 4-hydroxy[1]benzopyran-2-ones 1(a–d) with 25% excess of 2-bromobenzyl bromide 2a or 2-bromo-5-methoxy benzyl bromide 2b.
A catalytic amount of TBAB and potassium carbonate were added and irradiated in an open Erlenmeyer flask in a microwave oven for 4–10 min.
The tributyltin-hydride-mediated radical cyclisation of 3(a–h) was carried out under microwave irradiation to generate 12H-benzopyrano[3,2-c][1]benzopyran-5-ones 4(a–h) in 78–88% yield and in this technique yields were significantly improved and reaction time was shortened compared to the previously reported conventional radical cyclisation method.
American Psychological Association (APA)
Basu, Pradipta Kumar& Ghosh, Amrita. 2011. Microwave-Assisted Improved Regioselective Synthesis of 12H-Benzopyrano[3,2-c][1]benzopyran-5-ones by Radical Cyclisation. Organic Chemistry International،Vol. 2011, no. 2011, pp.1-6.
https://search.emarefa.net/detail/BIM-468689
Modern Language Association (MLA)
Basu, Pradipta Kumar& Ghosh, Amrita. Microwave-Assisted Improved Regioselective Synthesis of 12H-Benzopyrano[3,2-c][1]benzopyran-5-ones by Radical Cyclisation. Organic Chemistry International No. 2011 (2011), pp.1-6.
https://search.emarefa.net/detail/BIM-468689
American Medical Association (AMA)
Basu, Pradipta Kumar& Ghosh, Amrita. Microwave-Assisted Improved Regioselective Synthesis of 12H-Benzopyrano[3,2-c][1]benzopyran-5-ones by Radical Cyclisation. Organic Chemistry International. 2011. Vol. 2011, no. 2011, pp.1-6.
https://search.emarefa.net/detail/BIM-468689
Data Type
Journal Articles
Language
English
Notes
Includes bibliographical references
Record ID
BIM-468689