From Wikipedia, the free encyclopedia
Auwers synthesis | |
---|---|
Named after | Karl von Auwers |
Reaction type | Coupling reaction |
Identifiers | |
RSC ontology ID | RXNO:0000474 |
The Auwers synthesis is a series of organic reactions forming a flavonol from a coumarone. This reaction was first reported by Karl von Auwers in 1908.[1][2][3][4][5]

The first step in this procedure is an acid catalyzed aldol condensation between benzaldehyde and a 3-cyclooxapentanone to an o-hydroxychalcone. Bromination of the alkene group gives a dibromo-adduct which rearranges to the flavonol by reaction with potassium hydroxide.
Mechanism
[edit]A possible mechanism for the rearrangement step is shown below:

See also
[edit]References
[edit]- ^ K. Auwers, K. Müller, "Umwandlung von Benzal-cumaranonen in Flavonole", Ber. Dtsch. Chem. Ges., 41, 4233–4241 (1908) (doi:10.1002/cber.190804103137).
- ^ K. v. Auwers, P. Pohl, "Über die Umwandlung von Benzalcumaranonen in Flavonole", Liebigs Ann. Chem., 405, 243–294 (1914) (doi:10.1002/jlac.19144050302).
- ^ K. v. Auwers, P. Pohl, "Eine Synthese des Fisetins", Ber. Dtsch. Chem. Ges., 48, 85–90 (1915) (doi:10.1002/cber.19150480114).
- ^ K. v. Auwers, "Zur Bildung von Flavonolen aus Benzal-cumaranonen", Ber. Dtsch. Chem. Ges., 49, 809–819 (1916) (doi:10.1002/cber.19160490188).
- ^ K. v. Auwers, E. Auffenberg, "Über Cumaranone und Hydrindone", Ber. Dtsch. Chem. Ges., 52, 92-113 (1919) (doi:10.1002/cber.19190520114).
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url
url