Studies On Total Synthesis Of A Novel 8-O-4′Neolignan

Lignans are a significant secondary metabolite which is widely spread within the plant kingdom.These compounds exhibit an enormous class of physiologically activities such as anti-tumor,antibacterial,antiviral and antioxidant.Lignans are classified into two groups,classical lignans and neolignans,on the basis of their structure patterns.Classical lignans and neolignans are also classified into various subtypes.8-O-4 ′ neolignans are a significant subgroup within the neolignans.Mariamide A,isolated from the seeds of Silybum marianum,is classified under 8-O-4 ′ neolignans,which has good antioxidant and α-glucosidase inhibitory activity.In this paper,the first total synthesis of 8-O-4 ′ neolignan mariamide A is described.Using vanillin as the starting material,the synthesis of mariamide A is completed in nine steps.The key steps for the preparation of mariamide A involve an iodine-catalyzed bromomethoxylation reactions of an alkene group,a nucleophilic substitution followed by a sequential elimination reactions and a monoacylation reactions.This paper is divided into three parts:In the first part,the definition,structure classification,isolation and extraction,physiologically activities,biosynthesis of lignans and the synthesis review of 8-O-4′neolignans are decribed in detail.In the second part,the retrosynthetic analysis of 8-O-4 ′ neolignan mariamide A,the design of the synthetic route,the specific experimental operation,and the NMR data spectrum of the corresponding compound are explained in detail.In the third part,the key steps involved in the synthetic route is analyzed and discussed.Such as the design and optimization of I2-catalyzed bromomethoxylation reactions of an alkene group,a nucleophilic substitution followed by a sequential elimination reactions and a monoacylation reactions of 1,4-butanediamine.