Studies On Total Synthesis Of Natural Product 1,4-benzodioxane Lignans Cadensin G

1,4-Benzodioxane lignans are a class of lignans that are widely found in plant roots,stems and callus.1,4-Benzodioxane lignans have unique physiological activities such as insecticidal,liver-protective,anti-oxidant,anti-tumor,etc.Therefore,the agricultural and pharmaceutical industries have broad application prospects.The direct extraction of such lignans from plants has difficulties such as difficult extraction and complicated separation.However,the advantages of its many reaction sites and the ease of structural modification have attracted the attention of drug development researchers.Therefore,more and more researchers have turned their attention to total synthesis research.Nowadays,1,4-benzodioxane lignan synthesis technology mainly includes biological coupling method,bionic coupling method and chemical synthesis method.The first part is an introduction,which summarizes the definition,isolation and purification methods,biological activity,and synthesis of lignans in detail.Based on an in-depth analysis of the background and significance of the topic,the structure of the target compound was reverse-synthesized,and a total synthetic route of Cadensin G was designed.The second part is the experimental part,which introduces the optimal synthesis route of Cadensin G.For the synthesis of Cadensin G,syringaldehyde was used as the raw material,and the intermediate?E?-sinapyl alcohol was obtained through Knoevenagal condensation reaction and ester group reduction.Intermediate5,6-Dihydroxy-3-?methoxymethoxy?-9-oxo-9H-xanthen-1-yl acetate was obtained by using 2,3,4-trihydroxybenzoic acid as raw material through Friedel–Crafts reaction and selective protection of phenolic hydroxyl group.The two were coupled by K₃[Fe?CN?₆]to realize the total synthesis of Cadensin G.The third part is the result and analysis.This section analyzes and discusses the reaction mechanism,side reactions and reagents used in the key reaction steps in the entire synthetic route.We separately discussed the synthesis of?E?-3-?4-hydroxy-3,5-dimethoxyphenyl?prop-2-enoate,reduction reaction,the synthesis of 1,3,5,6-tetrahydroxyxanthone,selective protection of phenolic hydroxyl groups and biomimetic oxidative coupling.