First Total Synthesis of an Exceptionally Potent Antitumor Saponin, OSW-1

Abstract
OSW-1 (1), an acylated disaccharide cholestane saponin from Ornithogalum saudersiae with exceptionally potent antitumor activity, was first synthesized from commercially available dehydroisoandrosterone, l-arabinose, and d-xylose in total 27 steps with the longest linear sequence of 14 steps and in 6% yield.