Synthesis Of New Types Of Benzofuranones And Studys On The Cyclizaion Reaction Of Aromatic Aldehyde Hydrazones

In this paper, p-cresol was used to prepare a new type of benzofuranonederivative by muti-step reaction.In addition, the intramolecular cyclization reaction of aromatic aldehydehydrozone by use of NBS was researched. The main work in the synthesis ofbenzofuranone direvatives is listed below:Coenzyme Q10 was synthesized from p-cresol through four steps such asbromination, methoxylation, methylation, oxidation. And mend the technologicconditions of methoxylation, methylation and oxidation, to get higher yield.At room temperature, through the reaction of coenzyme Q0 and sodium ethylacetoacetate, which includes three steps such as conjugate addition, intramolecularcyclization and benzyl protection at 50℃, a new type of benzofuranone derivativewas gained by "one flask". With sodium methyl acetoacetate and sodium tert-butylacetoacetate used as starting meterial, the same product can be obtained.Testified thestructure of an unstable intermediate to propose a reaction mechanism. The finalproduct structure was testified by Hydrogen Nuclear Magnetic Resonance and singlecrystal X-ray diffraction. It is3-acetyl-5-hydroxy-6,7-dimethoxy-4-methylbenzofuran-2(3H)-one.The main work about the study on intramolecular cyclization reaction of aromaticaldehyde N-hydrozone by use of NBS:Hydrazine hydrate was used to prepare acetylhydrazine, benzoic acid hydrazide,p-fluoro Benzoic acid hydrazide, p-methoxy benzoic acid hydrazide,hydrazinecarboxylic acid methyl ester.The preparation of aromatic aldehyde N-acylhydrazoneswas obtained by the condensation of aromatic aldehydes with acylhydrazines.The possibility of intramolecular cyclization reaction of substituted aromaticaldehyde N-acylhydrazones was researched. At room temperature, in anhydrousdichloride methane, a new indole-substituted 1,3,4-oxadiazoles was obtained by useof NBS. It was the first time that 2,5-disubstituted-1,3,4-oxadiazole was prepared byuse of NBS.