Highly Selective Oxygenations of Olefins over Selenium Dioxide using Urea Hydrogen Peroxide as Oxidising Agent with Sesquiterpene Lactones

Presence of a hydroxyl group at C-3 position in guaianolides and at C-5 position in alantolides has been established biological active compounds as plant growth regulators. Sesquiterpene lactones like Dehydrocostus lactone and Isoalantolactone were subjected to allylic oxidations with selenium dioxide in combination with Urea Hydrogen Peroxide (UHP) replacing the common reagent TBHP to form the allylic alcohols. The reactions of dehydrocostus lactone and isoalantolactone with SeO2/UHP/PEG-400 were more selective and the yields were higher as compared to the reactions with SeO2/TBHP/CH2 Cl2. The structures of all the compounds were elucidated by spectroscopic techniques like IR, 1H NMR and 13C NMR . All the compounds so obtained were subjected for biological evaluation as plant growth regulators. The results were fairly good over the parent compounds.