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Aktivierte Chinone: O‐ versus C ‐Addition von Phenolen; eine neue, regiospezifische Synthese von Xanthonen, Thioxanthonen und N ‐Methyl‐9‐acridonen
Author(s) -
Müller Peter,
Venakis Thomas,
Eugster Conrad Hans
Publication year - 1979
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19790620732
Subject(s) - chemistry , phenols , catalysis , benzoquinone , quinone , organic chemistry , aryl , stereochemistry , medicinal chemistry , alkyl
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.