Oxidative cleavage of 3β-acetoxy-21-oxolup-18-en-28-oic acid by ruthenium tetroxide
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3β-Acetoxy-21-oxolup-18-en-28-oic acid was used as a starting compound for oxidative cleavage by ruthenium tetroxide generated in situ from ruthenium dioxide by sodium metaperiodate in a biphasic system. Tricyclic and tetracyclic acids of baccharane type were prepared by this reaction, and their structures were confirmed using spectral data. These acids were further used for synthesis of appropriate methyl and acetoxymethyl esters. All prepared compounds were tested on cytotoxic activity against CEM tumor cell line, and several compounds showed activity in low micromolar concentrations.
Keywordslupane triterpenoids oxidation ruthenium tetroxide cleavage decarboxylation cytotoxicity
This study was supported by project MSM6198959216 of the Ministry of Education, Youth and Sport of the Czech Republic and A/CZ0046/1/0022 of FM EEA/Norska from which chemicals and material were paid, and the Czech Science Foundation (305/09/1216) which supported the spectroscopic experiments. Indirect costs were paid by the Czech Ministry of Education (Z4 055 0506). The authors are indebted to Dr. P. Fiedler for measuring the IR spectra. Elemental analyses and optical rotations were measured by Dr. L. Holasova.
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