The Synthesis Of Pyrazoles Based On Propargyl Alcohol’ Oxidation&the Oxidation Of Aromatic Side Chains

In this thesis, two kinds of reaction were studied:(1) Synthesis of pyrazole derivatives (2)Selective oxidation of aromatic side chains. The concrete research content is as follows:(1) Synthesis of pyrazole derivativesThe synthesis and application of heterocyclic compounds is an area which has developed rapidlyand play a important role in the research and development of pharmaceuticals and pesticides. Amongthe heterocyclic compounds, pyrazole derivatives exhibit unique physiology activities, medicineactivities and coordinative abilities, which have been widely concerned in recent years.Many synthestic methods of pyrazole derivatives have been reported, in which the reaction ofacetylene ketones with hydrazine derivatives was widely used. In our research, pyrazole derivativeswere prepared by an one-pot reaction with propargyl alcohols as starting material via acetylene ketoneintermediate. The detailed procedures are as the following: propargyl alcohols were oxided by TBHPwith copper nanopartices or γ-Fe2O3-supported copper nanoparticles as catalysts in the presence ofbipydine as ligand in dichloromethane solution, then hydrazine or phenylhydrazine were added toreaction mixture directly. With the one-pot reaction based on the oxidation of propargyl alcohols,pyrazole derivatives were achieved with good to excellent yields. Compared to conventional methods,the reaction system has good functional groups tolerance and wide substrates scope On the other hand,the reaction could be completed in a short time at room temperature. Furthermore, the coppernanopartices catalyst, especially γ-Fe2O3-supported copper nanoparticles, could be recovered andrecycled for twice at least without obvious loss in catalytic activities.(2) Selective oxidation of aromatic side chainsThe preparation of aromatic aldehydes or ketones from arenes directly is still a challengingproject. The liquid phase oxidation is simple and less pollution compared with gas phase oxidation. Inour research,1,3,5-dimethylbenzaldehyde was prepared by liquid-phase selective oxidation ofmesitylene in solvent-free condition catalyzed by CoCl2/DDAB. Selective oxidation of other aromaticside chains was also explored. In the comparison of the previous similar catalytic system, our methodshowed higher yields and good selectivities to aromatic aldehydes or ketones.