Synthesis Of Racemic Bisabolane Sesquiterpenes And Heliannuol D

The aromatic bisabolene sesquiterpenoids are members widely distributed in nature.Man y of them possess good biological activities,such as antitumor, antibacterial,antioxidation.Hel iannuols D ,which has unique benzo-fused seven-membered cyclic ether structure and exhibit s good allelopathic activity,was isolated from the extracts of cultivated sunflowers. Based on t his,we studied the synthesis of these two types of compounds. We were the first successful ap plication of Johnson-Claisen rearrangement to construct the key intermediate of these two co mpounds. The synthesis of targets was completed and the reaction conditions were optimized.The main results were as follows:1,Studies on the synthesis of bisabolene sesquiterpenoids Five bisabolene sesquiterpenoids were synthesized from substituted acetophenones in six steps,which involved vinyl bromide grignard reaction,Johnson-Claisen rearrangement,catalyti c hydrogenation, iodomethane grignard reaction,dehydration,demethylation of aryl methyl eth ers. The structures of the compounds were confirmed by the spectrum data of NMR,MS,IR an d were found to be consistented with reported data.2,Studies on the synthesis of Heliannuol D The synthesis of the key intermediate 6d has been achieved from 2-methylhydroquinone, which involved methylation protection, Friedel-Crafts acylation, demethylation of aryl meth yl ethers promoted by AlCl3, benzyl Protection and then the same routes as the synthesis of bisabolene sesquiterpenoids.The seven ring closure product was obtained under the conditio n of K₂CO₃/MeOH after the epoxidation of 6d protected by TBS. Unfortunately,the isomers can not be separated by column chromatography.