- Flavones
Flavones are a class of
flavonoid s based on the backbone of 2-phenylchromen-4-one (2-phenyl-1-benzopyran-4-one) shown on the right.Natural flavones include
Apigenin (4',5,7-trihydroxyflavone),Luteolin (3',4',5,7-tetrahydroxyflavone) andTangeritin (4',5,6,7,8-pentamethoxyflavone). Synthetic flavones areDiosmin andFlavoxate Organic chemistry
In
organic chemistry several methods exist for the synthesis of flavones:
* theAllan-Robinson reaction
* theAuwers synthesis
* theBaker-Venkataraman rearrangement
* theAlgar-Flynn-Oyamada reaction Another method is the dehydrative cyclization of certain 1,3-diaryl diketones ["A facile synthesis of flavones using recyclable ionic liquid under microwave irradiation" Swapnil R. Sarda, Mohsin Y. Pathan, Vijaykumar V. Paike, Pandurang R. Pachmase, Wamanrao N. Jadhav, and Rajendra P. Pawar
ARKIVOC 2006 (xvi) 43-48 [http://www.arkat-usa.org/ARKIVOC/JOURNAL_CONTENT/manuscripts/2006/06-2210HP%20as%20published%20mainmanuscript.pdf Link] :]this particular study making use of an
ionic liquid solvent and microwave irradiation.Wessely-Moser rearrangement
The Wessely-Moser rearrangement (1930) [Wessely, F.; Moser, G. H. Monatsh. Chem. 1930, 56, 97.] has been an important tool in structure elucidation of flavonoids. It involves the conversion of 5,7,8-trimethoxyflavone into 5,6,7-trihydroxyflavone on hydrolysis of the
methoxy groups tophenol groups. It also has synthetic potential for example ["A Convenient Extension of the Wessely±Moser Rearrangement for the Synthesis of Substituted Alkylamino¯avones as Neuroprotective Agents In Vitro" Ronan Larget, Brian Lockhart, Pierre Renard and Martine Largeron Bioorganic & Medicinal Chemistry Letters 10 (2000) 835±838] ::
This
rearrangement reaction takes place in several steps: A ring opening to thediketone , B bond rotation with formation of a favorableacetylacetone -like phenyl-ketone interaction and C hydrolysis of two methoxy groups and ring closure.External links
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References
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