Synthesis of Lupane-Type Saponins Containing an Unusual α-<scp>D</scp>-Idopyranoside Fragment as Potent Cytotoxic Agents

A practical method for the preparation of benzoyl protected allyl and benzyl α-D-idopyranosides, and D-idopyranosyl trichloroacetimidate, from 1,2,3,4,6-penta-O-acetyl-α-D-idopyranose, is described. All derivatives can be prepared on a multigram scale and require only simple chromatographic purification. A concise synthesis of lupane triterpenes bearing an unusual D-idopyranoside fragment is described. All new compounds were evaluated in vitro for their cytotoxic activities. Novel saponins exhibited interesting cytotoxic activity in the micromolar range against human cancer cell lines including T-lymphoblastic leukemia CEM, breast adenocarcinoma MCF7, and cervical carcinoma HeLa, but also against normal human fibroblasts BJ.