Stereoselective Synthesis of Coreoside D and Determination of Its Absolute Configuration

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 usingd-malic acid. The stereochemistry at the C3-position of the natural product was determined to beRby comparing the [alpha](D)values of the synthetic stereoisomers with that reported for the natural product.