Auwers synthesis
The Auwers synthesis or Auwers flavonol synthesis is a name reaction from the field of organic chemistry . The reaction is named after the chemist Karl Friedrich von Auwers , who first published it in 1908.
The reaction makes it possible to produce flavonols, a subgroup of the flavonoids , from dibromo- coumarones .
Reaction mechanism
No mechanistic studies are available on Auwers flavonol synthesis. However, the following mechanism is suggested in the literature:
In the first reaction step, the oxonium ion 2 is formed with the deposition of a bromide ion . This is followed by the nucleophilic addition of a hydroxide ion to the carbonyl carbon . The intermediate product 3 is deprotonated, as a result of which the ring opens. As a result of an intramolecular Michael addition, 4 recycles to 5 . In the last step, the second bromide ion is released, creating the flavonol 6 .
Individual evidence
- ↑ K. Auwers, K. Müller, "Conversion of Benzal-Coumaranonen in Flavonole", Ber. German Chem. Ges. , 41 , 4233-4241 (1908) ( doi : 10.1002 / cber.190804103137 ).
- ↑ K. v. Auwers, P. Pohl, "On the Conversion of Benzal Coumaranones into Flavonols", Liebigs Ann. Chem. , 405 , 243-294 (1914) ( doi : 10.1002 / jlac.19144050302 ).
- ↑ K. v. Auwers, P. Pohl, "A Synthesis of Fisetins", Ber. German Chem. Ges. , 48 , 85-90 (1915) ( doi : 10.1002 / cber.19150480114 ).
- ↑ K. v. Auwers, "On the formation of flavonols from benzal-coumaranones", Ber. German Chem. Ges. , 49 , 809-819 (1916) ( doi : 10.1002 / cber.19160490188 ).
- ↑ K. v. Auwers, E. Auffenberg, "About Coumaranones and Hydrindones", Ber. German Chem. Ges. , 52 , 92-113 (1919) ( doi : 10.1002 / cber.19190520114 ).
- ↑ a b Li, JJ: Auwers Flavone Synthesis in: Name Reactions in Heterocyclic Chemistry Li, JJ; Wiley & Sons; Hoboken, NJ, 2005 , pp. 262-265.
