Kostanecki Acylation on:
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The Kostanecki acylation is a method used in 
organic synthesis
Organic synthesis is a special branch of chemical synthesis and is concerned with the intentional construction of organic compounds. Organic molecules are often more complex than inorganic compounds, and their synthesis has developed into one o ...
to form chromone
Chromone (or 1,4-benzopyrone) is a derivative of benzopyran with a substituted keto group on the pyran ring. It is an isomer of coumarin.
Derivatives of chromone are collectively known as ''chromones''. Most, though not all, chromones are also ...
s or coumarins
Coumarin () or 2''H''-chromen-2-one is an aromatic organic chemical compound with formula . Its molecule can be described as a benzene molecule with two adjacent hydrogen atoms replaced by a lactone-like chain , forming a second six-membered h ...
by acylation of ''O''-hydroxyaryl ketones with aliphatic acid anhydrides, followed by cyclization. If benzoic anhydride (or benzoyl chloride
Benzoyl chloride, also known as benzenecarbonyl chloride, is an organochlorine compound with the formula . It is a colourless, fuming liquid with an irritating odour, and consists of a benzene ring () with an acyl chloride () substituent. It is ...
) is used, a particular type of chromone
Chromone (or 1,4-benzopyrone) is a derivative of benzopyran with a substituted keto group on the pyran ring. It is an isomer of coumarin.
Derivatives of chromone are collectively known as ''chromones''. Most, though not all, chromones are also ...
called a flavone
Flavone is an organic compound with the formula . A white solid, flavone is a derivative of chromone with a phenyl (Ph) substituent adjacent to the ether group. The compound is of little direct practical importance, but susbstituted derivatives, t ...
is obtained.
Mechanism
The mechanism consists of three well-differentiated reactions:Ellis, G. P. (1977) ''Chromenes, Chromanones, and Chromones from The Chemistry of Heterocyclic Compounds'', Weissberger, A. and Taylor, E. C., eds.; Wiley & Sons: New York, vol. 31, p. 495. # Phenol ''O''-acylation with formation of a tetrahedral intermediate # Intramolecularaldol condensation
An aldol condensation is a condensation reaction in organic chemistry in which two carbonyl moieties (of aldehydes or ketones) react to form a β-hydroxyaldehyde or β-hydroxyketone (an aldol reaction), and this is then followed by dehydration to ...
to cyclize and to form a hydroxydihydrochromone
# Elimination of the hydroxyl
In chemistry, a hydroxy or hydroxyl group is a functional group with the chemical formula and composed of one oxygen atom covalently bonded to one hydrogen atom. In organic chemistry, alcohols and carboxylic acids contain one or more hydroxy ...
group to form the chromone (or coumarin)
Examples
* Alvocidib (flavopiridol) * Dimefline *Flavoxate
Flavoxate is an anticholinergic with antimuscarinic effects. Its muscle relaxant properties may be due to a direct action on the smooth muscle rather than by antagonizing muscarinic receptors.
Clinical uses
Flavoxate is used to treat urinary bl ...
See also
*Allan–Robinson reaction
The Allan–Robinson reaction is the chemical reaction of o-hydroxyaryl ketones with aromatic anhydrides to form flavones (or isoflavones).
If aliphatic anhydrides are used, coumarins can also be formed. (See Kostanecki acylation.)
:
Mechanism ...
* Baker–Venkataraman rearrangement The Baker–Venkataraman rearrangement is the chemical reaction of 2-acetoxyacetophenones with base to form 1,3-diketones.
This rearrangement reaction proceeds via enolate formation followed by acyl transfer. It is named after the scientists Wils ...
References
{{reflist Name reactions Organic reactions Coumarins