Synthesis of analogues of a potent antitumor saponin OSW-1

A series of side chain analogues (5a–e), a 22-glycosylated isomer (10), and 16β-O-l-arabinosyl (13a) or 16β-O-d-xylosyl (13b) analogues of OSW-1 were synthesized. All analogues were found to be less cytotoxic against breast and endometrial cancer cell lines than the natural product.