title: Synthesis of icariin from kaempferol through regioselective methylation and para-Claisen-Cope rearrangement.
abstract: The hemisynthesis of the naturally occurring bioactive flavonoid glycoside icariin (1) has been accomplished in eleven steps with 7% overall yield from kaempferol. The 4'-OH methylation of kaempferol, the 8-prenylation of 3-O-methoxymethyl-4'-O-methyl-5-O-prenyl-7-O-benzylkaempferol (8) via para-Claisen-Cope rearrangement catalyzed by Eu(fod)3 in the presence of NaHCO3, and the glycosylation of icaritin (3) are the key steps.
authors.affiliation: Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, China ; Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences, Chengdu 610041, China.
authors.forename: Qinggang
authors.initials: Q
authors.lastname: Mei
authors.affiliation: Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, China.
authors.forename: Chun
authors.initials: C
authors.lastname: Wang
authors.affiliation: College of Chemistry and Environmental Protection Engineering, Southwest University for Nationalities, Chengdu 610041, China.
authors.forename: Zhigang
authors.initials: Z
authors.lastname: Zhao
authors.affiliation: Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences, Chengdu 610041, China.
authors.forename: Weicheng
authors.initials: W
authors.lastname: Yuan
authors.affiliation: Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, China.
authors.forename: Guolin
authors.initials: G
authors.lastname: Zhang
keywords: Claisen–Cope rearrangement; flavonol; icariin; prenylation; regioselectivity