Study On The Synthesis Of Aminothiazole Derivatives And Biological Activity

Microwave irradiation and ultrasound irradiation as efficient thermal energy soures have become standard technique in the fields of organic chemistry. Compared to the classical heating methods, microwave irradiation and ultrasonic irradiation have the advantages of short reaction time, high yields, pure products and easy work up.Aminothiazole derivatives are important heterocyclic compounds, which are of great value in medical and agrochemical fields for their interesting biological and phsical properties, so they are concerned by organic chemist and pharmaceutical chemist.The dissertation focuses on synthesis of aminothiazole derivatives under micro wave irradiation and ultrasonic irradiation. The thesis consists of the following six sections:(1) A series ofα-bromoarylketones were obtained with ionic liquid as catalyst under microwave irradiation condition by the reaction of acetophenone (or substituted acetophenones) and N-bromosuccinimide. The reaction easily could be worked up with short reaction time, high yields and environmental friendliness. The catalyst could be reusable.(2) Three novel methods for synthesis of 2-aminothiazole derivatives were developed. Method 1:A lot of 2-aminothiazole derivatives were obtained under ultrasonic irradiation condition by the reaction of thiourea andα-bromoketones. Method 2:A series of 2-aminothiazole derivatives were prepared in 1-propanol under microwave irradiation condition by the reaction of thiourea, iodine and ketone. Method 3:Many 2-aminothiazole derivatives were obtained with ionic liquid as catalyst in 2-propanol under microwave irradiation condition by the reaction of thiourea andα-bromoketones.The preliminary bioassays indicate that a higher against G.zeae activity was observed for some compounds.(3) Two novel methods for synthesis of 2-acetaminothiazole derivatives under microwave irradiation were developed. Method 1:A series of 2-aminothiazole derivatives were obtained under microwave irradiation condition. Then the target compounds were obtained under microwave irradiation condition by the reaction of these derivatives and acetic anhydride. Method 2:The goal compounds were obtained by one-pot procedure by the reaction ofα-bromoarylketones,thiourea and acetic anhydride under microwave irradiation condition.(4) Two novel methods for synthesis of 2-aminothiazole schiff bases under microwave irradiation were developed. Method 1:The target compounds were prepared under microwave irradiation condition by the condensation of 2-aminothiazole with different aryl aldehydes. Method 2: The target compounds were obtained by one-pot procedure by the reaction ofα-bromoarylketones, thiourea and aryl aldehydes under microwave irradiation condition.(5) Two methods for synthesis of thiosemicarazones under microwave irradiation or ultrasound irradiation were developed. Method 1: A series of thiosemicarbazones were obtained by utilizing ketone,aromatic aldehyde and thiosemicarbazide under microwave irradiation. Method 2: A lot of thiosemicarbazones were obtained with ionic liquid as catalyst and water as medium under ultrasound irradiation by the reaction of ketone, aromatic aldehyde and thiosemicarbazide. The preliminary bioassays indicate that the activity against B.cinerea of some compounds was lower.(6) Four methods for synthesis of thiazole hydrazone derivatives were developed. Method 1: A series of thiazole hydrazone derivatives were obtained by utilizingα-bromoarylketones and thiosemicarbazide under ultrasound irradiation. Method 2: A series of thiazole hydrazone derivatives were obtained with ammonium acetate as catalyst in water by one-pot procedure by the reaction of ketone (aromatic aldehyde),α-bromoarylketones and thiosemicarbazide. Method 3: A lot of thiazole hydrazone derivatives were obtained by one-pot procedure by the reaction of ketone (aromatic aldehyde),α-bromoarylketones and thiosemicarbazide under environmentally solvent free conditions. Method 4 :Many thiazole hydrazone derivatives were obtained by one-pot procedure by the reaction of ketone (aromatic aldehyde),α-bromoarylketones and thiosemicarbazide under microwave irradiation.In summary, compared to the classical heating methods, the reaction easily could be worked up with short reaction time, high yields and environmental friendliness with all above methods.