Ultrasound-assisted Synthesis And Antibacterial Activity Ofα,β-unsaturated Ketone Derivatives

α, β-unsaturated ketone compounds are widely distributed in natural products and drug molecules. Due to the unique structural features, the compounds of α, β unsaturated ketone are valuable in synthetic chemistry. In this thesis,27α, β-unsaturated ketones were synthesized. Firstly, with cheap ethyl acetoacetate (methyl acetoacetate) as raw material, four a-methyl pyrrole derivatives were obtained by nitrosation and Knorr condensation. The pyrrole a-methyl was further oxidized to give four pyrrole aldehydes. Then, the aldol condensation reactions of the pyrrole aldehydes with acetone under ultrasonic radiation gave the expected a, β-unsaturated ketones in satisfactory yields. Combining alkali catalyzed reaction with ultrasound,23α, β-unsaturated ketone chalcones were synthesized. Then, by TLC, IR and1H NMR, structure of these synthesized compounds were identified and characterized. Study on antibacterial activity of these α, β-unsaturated ketones, in order to obtain leading compounds with antimicrobial activity, and provide valuable information for the development of new drugs. The main contents are:1:By consulting relevant literatures, research progress of α, β-unsaturated ketones was cataloged into a review, α,β-unsaturated ketones have a unique structure, with many excellent biological activities. Therefore, these compounds had wide application in various fields, such as agriculture, food, medicine and so on, The research on synthetic α, β-unsaturated ketones had been an important field of drug synthesis research.2:Pyrrolic compounds1a-1d were synthesized by using the acetyl acetate (acetyl acetate or acetyl acetone), sodium nitrite as the material. And then taking THF-HAc-H20as solvent, ammonium cerium nitrate as the oxidant, the compounds1a-1d are oxidized to give the Pyrrole aldehyde2a-2d. At last, Pyrrole aldehyde2a-2d as raw material, potassium hydroxide as a catalyst under ultrasonic40KHz, the condensation reaction with acetone was carried out to to give four of novel α, β-unsaturated ketones. Molecular structures of the target products were characterized.3:Under the role of ultrasonic irradiation at40KHz, a series of chalcones were obtained by using a variety of aromatic aldehydes and ketones as raw materials, ethanol as a solvent, a small amount of solid sodium hydroxide as a catalyst. The yields of chalcones are up to80～90%. The advantages of this method are the high yield and short reaction time. The structure of the target products are characterized by IR. 4:Antimicrobial Activity of the above target products was studied. Species included alginolyticus, Vibrio parahaemolyticus, Bacillus subtilis. Streptococcus faecalis, Pseudomonas aeruginosa, Pseudomonas fluorescens, Fusarium oxysporum, Geotrichum, yeasts. The experimental results show that some compounds have better inhibition for selected bacteria and fungi. Results show that the majority of α, β-unsaturated ketones have strong antibacterial activity to Fusarium oxysporum, few can inhibit the growth of bacteria. Chalcones c9and c14have broad-spectrum antimicrobial activity.They not only have strong inhibitory effects on Fusarium oxysporum, but also have strong effect on Pseudomonas aeruginosa and Vibrio alginolyticus. Inhibitory activity of the novel pyrrole α, β-unsaturated ketone compound (3a-3d) is weak for alginolyticus and Fusarium oxysporum5:Summed up the main work, research significance and prospect of the research study.