Chemoselective oxidation of oleanolic acid derivatives with ozone

@article{Kazakova2010ChemoselectiveOO,
  title={Chemoselective oxidation of oleanolic acid derivatives with ozone},
  author={Oxana B. Kazakova and Natal'ya I Medvedeva and Ol'ga S Kukovinets and Genrikh A Tolstikov and El'mira F Khusnutdinova and Lucjusz Zaprutko and Barbara Bednarczyk-Cwynar and Zdzisław Paryzek},
  journal={Chemistry of Natural Compounds},
  year={2010},
  volume={46},
  pages={397-399}
}
A method for preparing methyl esters of 12-oxoolean-28-oic and 3,12-dioxoolean-28-oic acids via ozonolysis of oleanolic acid methyl ester in CH2Cl2 at –60°C was proposed. It was found that oxidation of 2-cyano3,4-seco-4(23)-oleanenoic acid was chemoselective depending on the amount of ozone used.