Aktivierte Chinone: O- versus C-Addition von Phenolen; eine neue, regiospezifische Synthese von Xanthonen, Thioxanthonen und N-Methyl-9-acridonen
✍ Scribed by Peter Müller; Thomas Venakis; Conrad Hans Eugster
- Publisher
- John Wiley and Sons
- Year
- 1979
- Tongue
- German
- Weight
- 700 KB
- Volume
- 62
- Category
- Article
- ISSN
- 0018-019X
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✦ Synopsis
Activated quinones: O‐ versus C‐addition of phenols. New regiospecific syntheses of xanthones, thioxanthones and N‐methyl‐9‐acridones
The acid catalyzed reaction of phenols with activated quinones, e.g. 2‐methoxycarbonyl‐1, 4‐benzoquinone or 2‐acetyl‐1, 4‐benzoquinone, leads to substituted biphenylderivatives (C, C‐addition) as has been previously described [1]. O, C‐Addition of phenols has now been achieved by using 2‐methoxypyridin or 4‐dimethyl‐aminopyridin [4] as basic catalysts. The resulting substituted diphenylethers can serve as convenient starting materials for regiospecific syntheses of substituted xanthones, especially for 1, 4‐dimethoxyxanthones.
Arylthiols and N‐methyl‐N‐arylamines also react readily with activated quinones to give substituted di‐aryl‐thioethers and N‐methyl‐N, N‐diarylamines respectively; both types of compounds are convenient materials for regiospecific syntheses of substituted thioxanthones and N‐methyl‐9‐acridones.