Studies On Synthesis Of Dihydrobenzofuran Lignans

Lignans are naturally occurring plant phenols that are derived biosynthetically from phenylpropanoids. Most lignans occur freely in plants, but a small proportion of them co-exist with sugars to form glycosides in wood and resin of plants. Lignans can be classified in many types according to their structures, such as dibenzocyclooctadiene lignans, tetrahydrofuran lignans, arylnaphthalenes lignan et al.In this paper, we focused on the total synthesis of two benzofuran neolignans including the following three parts:Part one is the summary, we systematically introduced the the current study status and research progress of of lianan compounds about its definition, classification,metabolism, physicochemical properties, extraction and separation appraisal methods and physiological and pharmacological activities. This section simply expounded about the recent researches on total synthesis of the natural lignans and dihydrobenzofuran lignans. Then we put forward the research topic combined with the current research situation of dihydrobenzofuran lignans.The second part introduced the total synthesis of two benzofuran neolignans in detail. In this thesis, the benzofuran skeleton of target compounds was obtained,starting from cheaper diethyl malonate, via saponification reaction, Knoevenagel reaction, biomimetic oxidative coupling reaction followed by the protection of hydroxyl group with DHP. Then, using LiAlH4/AlCl3 as catalystwe, we got two different diol compounds which respectively reaction with acetyl chloride in pyridine to generate two new esters. Finally, after the DHP protecting group was removed, two target compounds were obtained.The third part, the important reactions and problems were explored, including synthesis of ferulic acid ethyl ester, ring opening of benzofuran skeleton et al and madethe thorough analysis to results. We expect that the synthetic strategy could be applied to the synthesis of other lignans with similar structures.