Synthesis Of Key Intermediate For Flavumounes B、Calodenin A And Calodenin B

Flavonoids have a broad range of pharmacological effects, which are attracting more and more attention. However, the abundance of some flavonoids in natural plants is rare.Moreover, the separation of some flavonoids is difficult. These seriously hindered the follow-up bioassay of these compounds.Flavumounes B, Calodenin A and Calodenin B are novel flavonoids which contain benzofuran motif. They are not widely distributed in natural plants, and the chemical synthesis routes of those couponds are not reported yet.In this paper three synthetic strategies to synthesis this kind of flavonoids were tested.In the first synthetic route, the key intermediate of Flavumounes B was successfully obtained by selective protection, iodination, selective deprotection, carbonylative insertion,hydrogenation from apigenin. The second synthetic strategy tries to synthesize Calodenin B,and this paper has successfully obtained the synthesis of 2-substituted-3-carbonylbenzofuran. In the third synthetic route, this paper tried to construct the 2-substituted-3 -carbonyl scaffold by oxidative coupling with 2,4,6-Trihydroxyacetophenone and 1,3- dicarbonyl compounds. After trying a lot of conditions, this paper has got the isomers of Calodenin B.In addition, we studied the effect of protection groups on the carbonylative insertion reaction and conditions to remove the acetyl groups in different substrates. This work suggested that steric hindrance protecting group should be avoid to use in the synthesis of these kind of compounds. This work provided a good reference to synthesis these kind of compounds in the future.