Nitroxide-mediated Heterocyclic Synthesis

This thesis deals with the studies on nitroxide-mediated heterocycle synthesis. It consists of four chapters:In the first chapter, the history and recent progress on nitroxide-mediated organic reactions and synthesis are briefly reviewed. The synthesis and physical properties of nitroxides are discussed first. The largest section focuses on their application as stoichiometric and catalytic oxidants in organic synthesis.In the second chapter, we report an efficient catalytic aerobic oxidative reaction to synthesis of2-substituted benzoxazoles using2-aminophenole and aldehydes as the commercial available starting materials and PS-supported-TEMPO and MCM-41-supported-TEMPO as the catalyst, respectively. When MCM-41-supported-TEMPO was used as the catalyst, the reaction gave the excellent yields of2-substituted benzoxazoles even after10times recycle of the catalyst.In the third chapter, the Cu/N-ligand/TEMPO catalytic system was first applied to the aerobic oxidative synthesis of heterocycles. As demonstrated,2-substituted quinazolines and4H-3,1-benzoxazines were synthesized efficiently from the one-pot reaction of aldehydes with2-aminobenzylamines and2-aminobenzyl alcohols, respectively, by employing CuCl/DABCO/4-HO-TEMPO as the catalysts and oxygen as the terminal oxidant.In the last chapter, we report a novel and efficient oxime radical O-atom and N-atom5-exo cyclization-promoted dioxygenation, oxyamination and diamination of inactivated alkenes to synthesize4,5-dihydroisoxazolines and cyclic nitrones using β,γ-and γ,δ-unsaturated ketoximes as the starting materials, respectively, under metal-free conditions. Commercial available DEAD (diethyl azodicarboxylate) and TEMPO were used as both oxime radical initiator and C-centred radical scavenger. This is also the first application of oxime radical in organic reactions.