serious synthetic problems, is poorly recognized. We report herein a protocol for the preparation of disubstituted lupane saponins (betulin bidesmosides) by treatment of their benzoates with potassium carbonate in dichloromethane / methanol solution. Cytotoxicity of all compounds was tested in vitro for a series of cancer cell lines, as well as normal human skin BJ fibroblasts. Presence of l-rhamnose moiety