Siberian Federal University

The article concerns an improved two-stage method of manufacturing betulinic acid from betulin. First the purified betulin was oxidized by chromium trioxide in acetone (Jones′ reagent) at 0°C. The complete reaction was carried out in half an hour yielding 55 % of betulonic acid when the betulin : chromium trioxide molar ratio was 1 : 7. Then the betulonic acid was reduced with sodium borohydride in two-phase catalytic system using quaternary alkyl ammonium salts as a catalyst at the ambient temperature. The optimal reaction conditions (the betulonic acid – sodium borohydride – quaternary ammonium salt ratio) as well as the best organic phase to provide 98.5 – 99.3 % betulinic acid yield were found.