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The Kostanecki acylation is a method used in organic synthesis to form chromones or coumarins by acylation of O-hydroxyaryl ketones with aliphatic acid anhydrides, followed by cyclization. If benzoic anhydride (or benzoyl chloride) is used, a particular type of chromone called a flavone is obtained.
Contents
Mechanism
The mechanism consists of three well-differentiated reactions:
- Phenol O-acylation with formation of a tetrahedral intermediate
- Intramolecular aldol condensation to cyclize and to form a hydroxydihydrochromone
- Elimination of the hydroxyl group to form the chromone (or coumarin)
Examples
References
Kostanecki acylation Wikipedia(Text) CC BY-SA