Synthesis of the cytotoxic gitogenin 3β-O-[2-O-(α-L-rhamnopyranosyl)-β-D-galactopyranoside] and its congeners

(25R)-5a-Spirostan-2a,3b-diol (gitogenin) 3 beta-O-[2-O(alpha-L-rhamnopyranosyl)-beta-D-galactopyranoside] (1), a cytotoxic spirostan saponin isolated from the underground parts of Hosta longipes (Liliaceae), was concisely synthesized. In this context, its congeners 2-4 were also prepared. All four Compounds showed comparable potency to dioscin in inhibition against the growth of tumor cells.