Study Of Synthesis And Bioactivity Of Novel2-phenyl-3,5-disubstituted-isoxazolidines

Isoxazoles represent a kind of compounds of great importance among fivemembered-heterocyeles. The research of the synthetical methods and the biologicalactivity of isoxazoline derivatives has always been one of important search realm inthe organic chemistry, medical chemistry and pesticide development. A lot ofliterature reported that isoxazoline compounds had hign-efficiency antifungalbioactivities, in recent years heterocyclic compounds have been more and morewidely used in pesticide and medicinal formulation. Amongst numerous developedheterocyclic compounds, isoxazoline derivatives have attracted considerable attentionin diverse potential biological properties such as antifungal, inseticidal and anticanceractivities, especially their unique antifungal.A new series of2-phenyl-3,5-disubstituted-isoxazolidines have been synthesizedby1,3-dipolar cycloaddition reaction between4-vinyl pyridine (orstyrene/N-vinyl-2-pyrrolidinone) and nitrones which were prepared by the reaction ofphenylhydroxylamine with aromatic carbonyl compounds. Structures of teen novelcompounds were characterized by1H NMR,13C NMR HRMS and IR. The reactionconditions for1,3-dipolar cycloaddition were optimized by single factor method, andthen the best reaction conditions were determined as75℃in the solvent of DMF. Inthe optimal reaction conditions, the majority of1,3-dipolar cycloadditions proceededsmoothly and obtained the desired products with satisfied yields.The biological activities of the target compounds were tested on ten kinds ofdifferent bacteria. The bioassay testing results show that the as-synthesized novelisoxazolidine compounds afford general activity towards different kinds of bacteria.Especially5-(pyridin-4-yl)-3-(4-chlorophenyl)-2-phenylisoxazolidine has excellentinhibitory effect and its inhibition ratio reaches more than70%on apple physalospora,cucumber wilt, phytophthora capsici and rice grain dry.