Beilstein J. Org. Chem.2015,11, 1220–1225, doi:10.3762/bjoc.11.135
, Southwest University for Nationalities, Chengdu 610041, China 10.3762/bjoc.11.135 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.
Keywords: Claisen–Cope rearrangement; flavonol; icariin; prenylation; regioselectivity
, amnesia, arthritis, asthenia, impotence, infertility, lumbago and other chronic illnesses [1][2]. Icariin (1), a 3,7-diglycosylflavone (Figure 1), is recognized as the major pharmacologically active ingredient of these plants [3][4], and has been used as the index for quality control of the herbs and
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Graphical Abstract
Figure 1:
Structures of icariin (1), icariside I (2) and icaritin (3).