Study On Protocols Of Pd-catalyzed Synthesis Of Xanthone Derivatives

The synthetic research on xanthone derivatives can be dated to 1960 s. Pharmacological studies have shown that xanthones have a very wide range of pharmacological activities, including anti-cancer, anti-virus, anti-microbial, anti-oxidization activity, and the mechanism of their pharmacological functions are still under study and exploration. Naturally-occurring xanthones have been separated from Gamboge Branch, Gentianaceae, Polygalaceae,Sankoh and Liliaceae. There many drawbacks in tratiditional synthesis of xanthone, such as harsh conditions, low yields, unavailable starting materatial, too many chemical operations. It is still highly demanding to develop a better method using cheap materials, environmental benign and sustainability. At the same time, Synthesis and modified of natural products is an important way in discovery new lead medicinal molecular in the development of new chemical drugs.Nowadays palladium-catalyzed reactions have drawn much attention of many organic chemists. Palladium catalyst are usually high efficient to react, low price and environmentally friendly, compared to other metals, such as rhodium, ruthenium, silver, etc. Recently, excellent works of palladium-catalyzed carbonylation and C-H activation have been reported. In this thesis, palladium-catalyzed synthesis of the xanthones skeleton from 2-phenoxyiodobenzene is reported.In conclusion, a new Palladium-catalyzed synthesis of xanthones has been developed. The best conditions were set as in the presence of 5%equiv of palladium acetate, 0.2equiv of tricyclohexylphosphine, 2equiv of trimethylacetic acid and 0.5equiv of sodium trimethylacetate hydrate as 2-phenoxyiodobenzene derivatives reacted smoothly. Altogether Six xanthone derivatives have been synthesized in the moderate yield. All the compounds were characterized by 1H and 13 C spectroscopy. Thus, we believe that this novel methodology will be a practical alternative to existing procedures for the synthesis of bioactive xanthones. Further studies on substrate scope and mechanism are currently underway and will be reported in due course.