The Study On Synthesis Of New Physiological Active Flavonoids And Flavone-O-glucosides

Flavonoids, also called bioflavoinoids, are a broad class of polyphenolic secondary metabolites abundant in plants and in human diet, Most flavonoids occur in nature as glycosides in which at least one of the OH group (most frequently, HO-C(3), HO-C(5), and HO-C(7)) of the chromophore (aglycone) is glycosylated by mono-to tetrasaccharides involving neutral sugars such as D-glycose, D-galactose, L-rhamnose, and D-xylose. Acylation of sugar OH groups by a variety of aliphaticand aromatic (p-hydroxybenzoic, p-coumaric, caffeic etc.) acids brings additional structural diversity to the flavonoid family. Nowadays, synthesis of sugar compounds to modify nature drugs has become an important field of pharmaceutical chemistry. This thesis aims at the studies on the syntheses of new flavonoids and 7-O- Flavonoid glycosides. Biological activities of flavonoids derivatives are also discussed in this thesis and three major parts are involved in this thesis.In the first part, the biological activities and the previous synthetic reports of flavonoids,Flavonoid glycosides and its application in pharmacology were introduced briefly in this thesis. Meanwhile, the classification, new extraction method, new synthesis method and structure identification method were also mentioned. The second part, the traditional Baker-Venkatarama rearrangement synthetic method of flavones is reformed and the new synthetic method of flavones simultaneity is achieved. In the new method the traditional etherification reaction and rearrangement reaction are finished by one-step in alkaline medium, two flavonoids compounds were synthesized(5a,5b)by a series synthetic steps including acetylation,esterification,rearrangement reaction. Moreover, On the basis of the designation, which Chalcone act as the key intermediates, six flavonoids compounds were synthesized(4c,5c,4d,5d,4e,5e). This method has advantages of mild reactions, easy sepration and high yields of products.In the last part, previous methods for the synthesis of flavone-O-glucosides are low-yielding. In this work, a series of 7-hydroxy flavonoid glycosides(2m,2n,4m,4n,6m,6n)have been synthesized from glucose or galactose by a series synthetic steps including acetylation,bromization,glycosidation,reduction.The synthetic procedure of glycosidation was modified by using anhydrous K2CO3 in a solvent mixture of DMF/acetone [V(DMF)/V(acetone)=(3:2)] and TBBA as a phase transfer catalyst. This method has advantages of mild reaction conditions, easy separation of products...