Microwave-assisted Concersion Of Oximes To 2-(Difluoromethoxy)benzonitrile/1,2-benzisoxazol-3-one And The Synthesis And Applications Of Chiral Quaternary Ammonium Salts Based On Chitosan

Microwave technology has been widely used in nano materials,pharmaceutical research,biological sciences and some other fields.Microwave as a heating source in organic synthesis has become a very efficient and attractive method to replace traditional heating.Microwave heating,not only can improve the reaction efficiency,but also can achieve some special reaction which can't be carried out by traditional heating.Part 1.The dehydration to nitrile and difluoromethylation of salicylaldehydeoximes was successfully achieved through one-pot multistep reaction under microwave-assisted condition.Eight 2-(difluoromethoxy)benzonitrile derivatives were synthesized in moderate yields.The structures of all target compounds were confirmed by nuclear magnetic resonance spectrum(1H NMR,13 C NMR,19 F NMR),high resolution mass spectrum(HRMS)and infrared spectrum(IR).The effects of microwave power,reaction temperature,reaction time,solvent,alkali and difluoromethylating reagent on the reaction were considered to obtain the optimized reaction conditions.Different substituents of oxime have been experimented to verify its range.A possible mechanism was proposed on the basis of the experiments and contrast tests.The conversion to isoxazole of salicylohydroxamic acids was successfully achieved through one-pot reaction under microwave-assisted condition.Eight 1,2-benzisoxazol-3-one derivatives were synthesized in moderate yields.The structures of all target compounds were confirmed by nuclear magnetic resonance spectrum(1H NMR)and infrared spectrum(IR).The effects of microwave power,reaction temperature,reaction time,solvent and addition regent on the reaction were considered to obtain the optimized reaction conditions.Different substituents of oxime have been experimented to verify its range.A possible mechanism was proposed on the basis of the experiments.Phase-transfer catalyst(PTC)has been widely studied and applied in laboratory and industrial production with the advantages of mild reaction condition,simple operation,fast reaction rate,less side reaction and high selectivity.In recent years,the rapid development of new chiral phase-transfer catalysts has added new vitality in chiral phase-transfer catalysis.Chitosan is used widely,and as a natural chiral molecule,the value of chitosan in asymmetric catalysis is worth developing and using.Part 2.Nine different chiral quaternary ammonium salt phase-transfer catalysts based on chitosan oligosaccharide structure were prepared by using chitosan and chiral binaphthyl through multistep reaction.And new phase-transfer catalysts were used in the asymmetric alkylation reaction of N-(diphenylmethylene)glycine tert-butyl ester and asymmetric epoxidation addition and Michael addition reaction of chalcone.The successful synthesis and application of new type chiral quaternary ammonium salt phase-transfer catalysts based on chitosan oligosaccharide structure has extended types of chiral phase-transfer catalysts,simplified the synthesis steps of chiral phase transfer catalyst based on binaphthyl structure,and also provided a new way for the development of chiral value of chitosan.