119892-40-9Relevant articles and documents
Method for preparing baicalein
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Paragraph 0016, (2017/01/12)
The invention discloses a method for preparing baicalein. According to the method, 2,6-dimethoxy-p-benzoquinone used as an initial raw material is subjected to reduction, Friedel-Crafts acetylation, claisen condensation, dehydrogenation oxidation cyclization and demethylation five reactions to obtain baicalein with high yield. The method uses low-price and easily-available initial raw material, reagent and the like, has few synthesizing steps, is easy and convenient to operate and easy for production control, has high product yield and high purity, and is suitable for large-scale preparation and production application of baicalein.
Use of acyl substituents to favour 2,3-epoxidation of 5,7-dioxygenated flavones with dimethyldioxirane
Compton, Benjamin J.,Larsen, Lesley,Weavers, Rex T.
, p. 718 - 726 (2011/03/19)
The reaction of 5,7-dimethoxyflavone with dimethyldioxirane (DMDO) gives the 2,3-epoxide rapidly at first. However, low levels of ring A hydroxylated by-products are also formed. With increasing proportions of DMDO, demethylation at C-5 becomes apparent and consumption of substrate is not matched by further significant build-up of the epoxide. Deactivation of ring A by the use of acyl groups removes this complication. 5,7-Diacylflavones give excellent yields of epoxides and monoacyl derivatives also react in good yield. Ionization potential maps derived from density functional theory calculations (B3LYP/6-31G), provide good visual indicators of the relative reactivity of the key nucleophilic loci. The epoxides may be isolated as such, or transformed into flavonols by treatment with p-toluenesulfonic acid.
A novel route to 5,7-dimethoxy-6-hydroxyflavone
Osorio-Olivares, Mauricio,Cassels, Bruce K.,Sepulveda-Boza, Silvia,Rezende, Marcos Caroli
, p. 815 - 819 (2007/10/03)
A novel route to 5,7-dimethoxy-6-hydroxyflavone is described, involving the cyclization of an intermediate phosphorane as the key step.