3,4-Benzotropolone and Related Compounds. V. Bromo- and Hydroxy-2,3-benzotropones
- 1 December 1968
- journal article
- research article
- Published by Oxford University Press (OUP) in Bulletin of the Chemical Society of Japan
- Vol. 41 (12) , 2942-2948
- https://doi.org/10.1246/bcsj.41.2942
Abstract
Isomeric 5,7- and 4,7-dibromo-2,3-benzotropones were prepared, not via 2,3-benzotropone, but by the bromination and subsequent dehydrobromination of 2,3-benzocycloheptenone. The tropone structure of these compounds was based on spectral data and hydrogenation to 2,3-benzocycloheptenone. The dibromo-2,3-benzotropones, when treated with hydroxylamine, underwent cine-reaction to 5- and 4-bromo-6-hydroxylamino-2,3-benzotropone oximes, which were then hydrolyzed and debrominated to the same 6-hydroxy-2,3-benzotropone. 5,7,5′-Tribromo-2,3-benzotropone was obtained by the drastic bromination, followed by the dehydrobromination, of 2,3-benzocycloheptenone. The position of a hydroxyl group in 6-hydroxy-2,3-benzotropone was confirmed by oxidation to o-carboxycinnamic acid, while that of the 5′-bromo substituent in 5,7,5′-tribromo-2,3-benzotropone was confirmed by hydrogenation to 5′-bromo-2,3-benzocycloheptenone.Keywords
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