Synthesis and Evaluation of the α-D-/α-L-Rhamnosyl and Amicetosyl Digitoxigenin Oligomers as Anti-tumor Agents.

A highly regio- and stereo-selective asymmetric synthesis of rhamnosyl- and amicetosyl-digitoxigenin analogues has been established via palladium-catalyzed glycosylation followed by bis-/tris-dihydroxylation or bis-/tris-diimide reduction. The α-l-rhamnose and α-l-amicetose digitoxin monosaccharide analogues displayed stronger apoptosis inducing activity and cytotoxicity against non-small cell human lung cancer cells (NCI-H460) than its d-diastereomeric isomers in a sugar-chain length dependent manner.