Transformative reaction on triterpenoids: action of hydrogen peroxide in presence of selenium dioxide on oxime derivative of taraxerone and antimicrobial activity of isolated compounds

Although studies on oxidation of triterpenoid ketones with hydrogen peroxide and selenium dioxide have been reported, literature reports on the effect of the oxidizing agent on the oxime derivative of triterpenoid ketones are scanty. Thus in continuation of our previous studies on the transformative reactions on pentacyclic triterpenoids of lupane and friedelin skeleton and in order to examine the nature of the products formed on the oxidation of oxime derivatives of 3-keto-triterpenoids having gem dimethyl group at C4 and a double bond at ring D (between C14-C15), the oxidation of keto-oximes of taraxerone with hydrogen peroxide and selenium dioxide was taken up and characterisation of the products (A -D) along with the evaluation of their preliminary biological activity were studied in this work. The oxime derivative of taraxerone (1a) in tertiary butanol was refluxed with selenium dioxide and hydrogen peroxide. The residue obtained after recovery of solvent by distillation was extracted with ether and separated into neutral and acid parts using usual method.