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Allan–Robinson reaction

Lianyungang Klinechem Co.,Ltd | Updated: Nov 28, 2018

The Allan–Robinson reaction is the chemical reaction of o-hydroxyaryl ketones with aromatic anhydrides to form flavones (or isoflavones).[1][2][3][4]

If aliphatic anhydrides are used, coumarins can also be formed. (See Kostanecki acylation)

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Reaction Overview

Mechanism

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The first step is an enolization which is a proton transfer created a hydroxide instead of a carbonyl and an alkene instead of an alkane. The second step is an acylation in which the newly formed bond from the enolization attacks an electrophilic carbon in the anhydride. The third step displays the carboxylate functionality leaving since it is the best leaving group. As a result the resulting carboxylate attacks an alpha hydrogen to create the enol functionality again in step four. The fifth step shows the nucleophilic hydroxide attacking the carbonyl carbon to create a new six membered heterocyclic ring. The resulting structure undergoes a proton transfer in step 6 to achieve the final product. All six of these steps occur in the reaction flask in the presence of heat. [4] [5]

References

1.     Jump up^ Allan, J.; Robinson, R. J. Chem. Soc. 1924125, 2192.

2.     Jump up^ Dyke, S. F.; Ollis, W. D.; Sainsbury, M. J. Org. Chem. 196126, 2453. (doi:10.1021/jo01351a072)

3.     Jump up^ Wheller, T. S. (1952). "Flavone"Organic Syntheses32: 72. doi:10.15227/orgsyn.032.0072.

4.     Jump up to:a b Jie Jack Li (2009). Name Reactions. A Collection of Detailed Reaction Mechanisms 4th Edition. Berlin, De: Springer. ISBN 978-3-642-01052-1.

5.     Jump up^ Graham,, Solomons, T. W. Organic chemistry. Fryhle, Craig B.,, Snyder, S. A. (Scott A.), (11e ed.). Hoboken, NJ. ISBN 9781118147399OCLC 820665397.

See also

·         Baker–Venkataraman rearrangement

·         Kostanecki acylation

·         Robert Robinson (organic chemist)


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