Study On The Total Synthesis Of Natural Product (±)-Gracilioether H

Natural products of gracilioether family were firstly isolated from Agelas gracilis in 2009.This family has been isolated from the sponges Plakinastrella mamillaris.Structually,these compounds generally feature a tricyclic skeleton.Many of the compounds in this family show antibacterial activity in vitro.Due to the fact that gracilioether H have high antimalarial activity,we attempted to synthesize this compound.This thesis use ethyl 2-bromobutyrate as the starting material to synthesize lactone compound 128.The compound 128 was then substituted with2-bromomethyl-1-butene to afford 129.Hydroboration oxidation and Dess-Martin oxidation of 129 gave aldehyde 130,which was allowed to react with propyl ylide to afford olefin 131.Compound 131 under went Heck reaction to give 124,and Carbonyl reduction of 124,followed by singlet oxygen Diels-Alder reaction,afforded 1,2-dioxane ring structure 133.The double bond of compound 133 was reduced to afford 134.Target compound 135 was obtained by oxidation of 134.