Study On The Synthesis Of Natural Flavones

Flavonoids, a major class of polyphenolic natural products found in plants. They include flavones, isoflavones, flavonols and so on. Many studies have shown that they are biologically active molecules exhibiting antiviral, antiinflammatory, hepatoprotective, antioxidant, antithrombotic, vasodilating, antiviral and anticarcinogenic activities. However, the amount of flavonoids which isolated from plants are very limited, it is unable to meet people’s need. Therefore, the study on the synthesis of flavonoids from available materials will have a bright future.We reported two new methods of the synthesis of flavonoid compounds which we need on the basis of our previous work. At the same time, we performed some experiments on the synthesis of isoflavones. It would help us to obtain the isoflavones such as genistein.This paper was composed of three sections as follows:Part one The synthesis of apigenin Method one:An efficient synthesis of apigenin using1,3,5-trimethoxybenzene and anisaldehyde as starting materials is described, involving Friedel-Crafts acylation, selective demethylation, Clai sen-Schmidt condensation, cyclisation, and demethylation.Method two:Firstly, we get the compound2’,4,4’,6’-tetramethoxychalcone from1,3,5-trimethoxybenzene via Friedel-Crafts acylation and Claisen-Schmidt condensation, then followed by selective demethylation, cyclisation and demethylation to obtain apigenin.Part two The synthesis of chrysin and luteolinMethod one:Chrysin was synthesized by a reaction sequence starting from1,3,5-trimethoxybenzene via Friedel-Crafts acylation, selective demethylation, Claisen-Schmidt condensation, cyclisation and demethylation. The synthesis of luteolin was the same as chrysin.Method two:1,3,5-trimethoxybenzene was used as the starting material, respectively react with cinnamic acid and3,4-dimethoxycinnamic acid via "one pot" reaction, cyclisation and demethylation to obtain chrysin and luteolin.Part three The synthesis of genisteinGenistein was synthesized by starting from1,3,5-trimethoxybenzene and4-methoxyphenylacetic acid via Friedel-Crafts acylation, Vilsmeier reaction and "one pot" reaction.