We report the stereoselective synthesis of (3S)- and (3R)-coreoside D. The conjugated diyne in the C1–C14 moiety was synthesized through two types of palladium-catalyzed cross-coupling reaction. The introduction of the glucopyranose was achieved by a glycosylation reaction using an imidate derivative in the presence of a Lewis acid. The asymmetric center at the C3-position was constructed by the chiral-pool method using d-malic acid. The stereochemistry at the C3-position of the natural product was determined to be R by comparing the [α]D values of the synthetic stereoisomers with that reported for the natural product.
We investigated the synthesis and herbicidal activity of 23 toxoflavin analogs, 1a-w, in which aromatic rings (R) were introduced into the C-3 position. In paddy field conditions, 1k (R=2-CF 3 -C 6 H 4 ) and 1w (R=2-thienyl) showed excellent herbicidal activity. Under upland field conditions, we found that toxoflavin analogs 1a (R=C 6 H 5 ), 1n (R=2-CH 3 O-C 6 H 4 ), and 1p (R=4-CH 3 O-C 6 H 4 ) exhibited wide herbicidal spectrum against Echinochloa crus-galli (L) var. crus-galli (ECHCG), Chenopodium album, and Amaranthus viridis (AMAVI). The analog with the 2-fluoro group on benzene ring 1b also showed high herbicidal activity against both ECHCG and AMAVI.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.