Allan–Robinson reaction
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Chemical reaction
The Allan–Robinson reaction is the
If
aliphatic anhydrides are used, coumarins can also be formed. (See Kostanecki acylation
.)
Reaction overview
Mechanism
The o-hydroxyaryl ketone first undergoes tautomerization to form the respective enol. The pi electrons of the double bond then attack the electrophilic carbon of the anhydride; a carboxylate anion is subsequently lost as a leaving group. The carboxylate anion then attacks an alpha hydrogen to form an enol. The nucleophilic hydroxyl group then attacks the carbonyl carbon to form a six-membered heterocyclic ring. A proton is abstracted from the hydroxyl group of the enol to form a ketone, and the remaining hydroxyl group is lost as a leaving group in a concerted step to afford the final product.[4][5]
See also
- Baker–Venkataraman rearrangement
- Kostanecki acylation
- Robert Robinson (organic chemist)
References
- J. Chem. Soc.1924, 125, 2192.
- )
- .
- ^ ISBN 978-3-642-01052-1.
- )
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