Of .3 - Methoxyflavone New Synthetic Studies

Flavonoids from a class of polyphenos which are ubiquitous in nature, possess wide spectrum and importance of biological and pharmacological activities, such as antioxidant, anticarcinogenic, antiallergic, antimicrobial, antiinflammatory activity as well as anticardiovascular and analgesic properties. Due to specific antiviral activity and antitumor activity of 3-methoxyflavones, tremendous attentions are given to the synthesis of 3-methoxyflavones.In this paper, the process of preapring the 3-methoxyflavones was described concisely as follows. Firstly, chalcones were prepared from o-hydroxyacetophenone derivations and benzaldehyde derivations by Claisen-Schmidt reaction, which were oxidative cyclized under the effect of SeO2 to give flavones. Then, flavones were converted to 3-bromo?avones by selective bromination with Pyridinium bromide perbromide. At last, 3-methoxyflavones were obtained from 3-bromo?avones via methoxylation with sodium methoxide.Chalcones were prepared from o-hydroxyacetophenone derivations and benzal -dehyde derivations by Claisen-Schmidt reaction in 20% KOH solution and taking TBAB as catalyst, the yields were about 60%⁸0%; Meanwhile, 2-nitrochalcone was obtained by gringing method.The synthetic route for flavones were proposed. Under the condition of 2 equivalen SeO2 and octanol as solvent, a series of flavones were obtained, the yields were about 40%⁶0%.The transformation of flavones into the corresponding 3-bromo derivatives proceeded smoothly using the pyridinium bromide perbromide, the yields were about 70%⁹0%.The methoxylation is the key step of the whole reaction route. Under the effect of sodium methylate and TBAB as catalyst, 3-bromoflavones were converted to 3-methoxyflavones, the yields were about 40%⁶0%.In the process of achieving the main objective(flavones were convert to 3-methoxyflavones) of the thesis, some of flavonoids, such as chalcones,flavones,3-bromoflavones,3-methoxyflavones were synthesised, which were laid substantial material foundation for further study of the biological activity or structure-activity relationship.The structures of the target compounds and key intermediates were confirmed by IR, ¹H NMR and ¹³C NMR.