Synthesis And Properties Research Of Isoxazol(in)e Derivatives

Amongst five-membered heterocycles,isoxazol(in)es represent a class of compounds of great importance in organic synthesis,the discovery and development of drugs,catalyzed reactions and the area of electrochemistry because they have particular chemical structures and intrinsic biological activities.So isoxazol(in)es become one of important subjects for organic synthesis and drug chemistry.As continuation of our studies of the synthesis of isoxazol(in)es,we mainly developed for the liquid-phase synthetic methodology of isoxazol(in)es and their derivatives.We also presented the synthesis of three of ferrocenylsubstituted isoxazoles using the 1,3-dipolar cycloaddition reaction,and their electroanalytical behavior was studied by cyclic voltammetry(CV).Then,The catalytic activity of 2,6-bis-(5-ferrocenylisoxazole-3-yl)pyridine as a ligand in the present of palladium(â…¡)acetate was tested.At first,PEG-supported acrylate reacted with benzaldehyde to give PEG-supportedα,β-unsaturated ester through Baylis-Hillman reaction. The PEG-supported Baylis-Hillman adduct reacted with in situ generated nitrile oxides through 1,3-dipolar cycloaddition,followed by cleavage from the resin and purified by chromatography on silica gel to give a pair of diastereomers of isoxazolines in moderate de value.All compounds were characterized by ¹HNMR,¹³CNMR,FT-IR and mass spectroscopy. The configuration of diastereomers was determined by X-ray diffraction. The mechanism of this 1,3-dipolar cycloaddition was studied by quantum chemistry calculation methods.By examination of the corresponding TS for the reaction or reactants or products,the same conclusion that the amount of the diastereomer with(R,S)configuration was more than that of other diastereomer with(R,R)configuration was extracted.This conclusion was agreed with our experimental result and theoretical prediction.Then,three of ferrocenylsubstituted isoxazol(in)es were obtained by treating ethynylferrocene or vinyl ferrocene with nitrile oxides derived from 2,6-pyridinedicarboxaldehyde and m-benzenedicarboxaldehyde via 1,3-dipolar cycloaddition.These new compounds were characterized by ¹HNMR,¹³CNMR,FT-IR,mass spectroscopy and elemental analyse.The structure of 2,6-bis-(5-ferrocenylisoxazole-3-yl)pyridine was further determined by X-ray diffraction.Their electroanalytical behavior was also studied by cyclic voltammetry(CV).The catalytic activity of 2,6-bis-(5-ferrocenylisoxazole-3-yl)pyridine as a ligand in the present of palladium(â…¡)acetate used in catalyzed Sonogashira reaction and Heck reaction was tested.The result showed 2,6-bis-(5-ferrocenylisoxazole-3-yl)pyridine was an efficient,stable ligand of palladium,and its applications in other reactions are carrying out in our group.