Total Synthesis of Cardenolides Acospectoside A and Acovenoside B.

Acospectoside A () and acovenoside B (), two cytotoxic cardenolides extracted from the venomous South African bush , are distinguished by their unique structural motifs of the l-acovenose moiety at C-3 and a 1β--acetylated cardenolide aglycone. Here, we report the synthesis of these cardiac glycosides featuring delicate introductions of the 1--acetyl group under acid-catalyzed conditions, 14β-OH by Mukaiyama hydration, and a C17-butenolide moiety by Stille coupling.

Synthesis of Acovenosides: Cardiac Glycosides with Potent Antitumor Activities.

Acovenoside A (), a cardiac glycoside featuring a unique l-acovenose at C-3 and a 1β,3β,14β-trihydroxy aglycone (namely, acovenosigenin A), shows promising antiproliferative activities. Herein, we report the synthesis of acovenoside A () together with a panel of its congeners. The synthesis features the stereoselective introduction of the 1β,14β-OH and C17-butenolide moieties starting from androstenedione () and gold(I)-catalyzed glycosylation with superarmed glycosyl -alkynylbenzoates as donors.

Chemical Synthesis of Fucosylated Chondroitin Sulfate Oligosaccharides.

Fucosylated chondroitin sulfates (FuCSs) are a unique type of polysaccharides occurring in sea cucumber that show a variety of biological activities. In particular, well-defined FuCS oligosaccharides, consisting of a trisaccharide repeating unit of β-d-GalNAc(4,6-diS)-(1→4)-[α-l-Fuc(2,4-diS)-(1→3)]-β-d-GlcUA, display potent anticoagulant activity via selective inhibition of the intrinsic tenase, which could be developed into anticoagulant drugs without bleeding risk. Herein, we report an effective approach to the synthesis of FuCS oligosaccharides, as demonstrated by the successful elaboration of FuCS tri-, hexa-, and nonasaccharides.