Abstract
Regioselective electro-bromination of benzofuran (2) was achieved successfully by an adequate choice of solvents and bromide salts to afford 5-bromobenzofuran (1), 5,7-dibromobenzofuran (3), and 2,3-dibromo-2,3-dihydrobenzofuran (4), respectively. Upon electrolysis of benzofuran (2) in AcOH/H2O (100/1) containing NH4Br, substitution at the C(5)-position of benzofuran (2) proceeded smoothly to afford 5-bromobenzofuran (1). After passage of totally 4 F/mol of electricity in a similar medium, 5,7-dibromobenzofuran (3) was obtained as a sole product. On the other hand, electrolysis of benzofuran (2) in CH2Cl2/H2O (1/1) and/or AcOH/H2O (10/1) in the presence of either NaBr or NH4Br afforded 2,3-dibromo-2,3-dihydrobenzofuran (4), exclusively.
| Original language | English |
|---|---|
| Pages (from-to) | 825-831 |
| Number of pages | 7 |
| Journal | Heterocycles |
| Volume | 54 |
| Issue number | 2 |
| Publication status | Published - Feb 1 2001 |
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Keywords
- 2,3-Dibromo-2,3-dihydrobenzofuran
- 5-Bromobenzofuran
- Benzofuran
- Bromination
- Electrolysis
ASJC Scopus subject areas
- Organic Chemistry
Cite this
Tanaka, H., Kawakami, Y., Kuroboshi, M., & Torii, S. (2001). Substitution vs. addition. Regioselective electro-bromination of benzofuran. Heterocycles, 54(2), 825-831.