tailieunhanh - Báo cáo vật lý: "Selective Oxygenation and Plant-Growth Regulatory Activity of Sesquiterpene Lactones"

Tuyển tập các báo cáo nghiên cứu khoa học trên tạp chí khoa học vật lý quốc tế đề tài: Selective Oxygenation and Plant-Growth Regulatory Activity of Sesquiterpene Lactones | Journal of Physical Science Vol. 21 2 99-107 2010 99 Selective Oxygenation and Plant-Growth Regulatory Activity of Sesquiterpene Lactones Sabir Hussain and Mukta Sharma Department of Chemistry Rawal Institute of Engineering and Technology Faridabad-121002 India Maharishi Dayanand University Rohtak Haryana India Corresponding author sabir_zhirka@ Abstract 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 tertbutyl 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. Keywords sesquiterpene lactones allylic oxidation urea hydrogen peroxide plant growth regulatory activity 1. INTRODUCTION Selective oxidation of alkenes to allylic alcohols known as allylic oxidation is an important transformation in organic chemistry. Several reagents are known1 to carry out this reaction but selenium dioxide SeO2 has been found to be a promising reagent. Some difficulties such as the removal of colloidal selenium and the formation of organo-selenium by-products have been circumvented by the Sharpless method 2 which uses catalytic SeO2 in combination with tert-butyl .