Selective Oxygenation and Plant-Growth Regulatory Activity of Sesquiterpene Lactones

Presence of a hydroxyl group at the c-3 position in guaianolides and at the c-5 position in alantolides has been established in biologically active compounds that act as plant-growth regulators. sesquiterpene lactones like dehydrocostus lactone and isoalantolactone were subjected to allylic oxidations with selenium dioxide (seo2) in combination with urea hydrogen peroxide (uhp) replacing the common reagent tert-butyl hydroperoxide (tbhp) to form allylic alcohols. the reactions of dehydrocostus lactone and isoalantolactone with seo2/uhp/polyethylene glycol-400(peg-400) were more selective, and the yields were higher than reactions with seo2/tbhp/ dichloromethane (ch2cl2). the structures of all of the compounds were elucidated by spectroscopic techniques like infrared (ir) spectroscopy, proton nuclear magnetic resonance ( 1h nmr) and carbon 13 nuclear magnetic resonance (13c nmr). all of the obtained compounds were subjected to biological evaluation as plant-growth regulators. the results were fairly good compared to the parent compounds