| Isoxazoline compounds,a class of five-membered heterocyclic compounds containing oxygen-nitrogen heteroatoms,are widely found in pharmaceuticals,natural products,pesticides and chiral ligands.Therefore,the synthesis of isoxazolines has always been a hot research topic in the field of organic synthesis.In other hand,alkenes and nitromethane are cheap and commercially available chemicals.Electrosynthesis of isoxazolines from alkenes and nitromethane takes advantages of green and effective.This thesis includes the following two parts:Part One: Electrochemically construct the isoxazoline aldoximes via activation of nitromethaneThe reported methods for the synthesis of suffer from several drawbacks,such as low step economy,low atom economy and the use of excessive oxidants and reductants.Activation of nitro groups has attracted much attention,because that enables achievement of highly valuable reactions.However,there is no method for synthesis of isoxazoline aldoximes from nitromethane,which is also a commonly used solvent.In this section,isoxazoline aldoximes were synthesized efficiently through the green and sustainable electrochemical activation of nitromethane and readily available alkenes in a single step under transition-metal catalysts and oxidant-free conditions.This reaction has several advantages,such as mild conditions,the use of inexpensive graphite electrodes,and good substrate tolerance.Part Two: Mechanistic study on electrochemical activation of nitromethane to construct isoxazoline aldoximesBased on the mechanistic results fromcontrol experiments,deuterium-labeled experiments,KIE experiments,CV tests,free radical scavenging and byproducts analysis,a possible reaction mechanism was proposed.Moreover,an active reaction intermediate was successfully detected via high-resolution mass spectrometry.The proposed reaction pathway was furtherly proved by the DFT calculations.Our method provides a new pathway for synthesizing isoxazolines via activation of nitromethane. |
