Synthesis And Study Of The Heterocylic Small Molecules Compounds Under Microwave Irradiation

This paper is divided into six chapters.Chapter one 2,5-disubstituted 1,3,4-oxadiazoles are widely used in the industry of medicine and material because of their wide spectrumof biological and optical activities. The new methods, new reagents and new technologies, such as polymer supported organic synthesis, microwave irradiation and solventfree reaction, of synthesis of 2,5-disubstituted 1,3,4-oxadiazoles are reviewed in this chapter.Chapter two A series of substituted 1,3,4-oxadiazoles are synthesized by cyclization of several acids with aroyl hydrazines in the presence of a polymer supported cyclizing agent under the solvent-free and microwave irradiation conditions. We studied different affects of varies conditions (ratios, solvent, catalysts, irradiation power and time) on the reactions. Then we synthesized 36 new2,5-disubstituted 1,3,4-oxadiazoles. The fluorometric spectrum of some compounds is analyzed.Chapter three 1,2,4-triazolo[3,4-6]-1,3,4-tbiadiazole derivatives have represented an interesting class of compounds possessing a wide spectrum of biological activities, since they combined two bioactive sub-structure, 1,2,4-triazole and 1,3,4-thiadiazole. This chapter has described the characterization, biological activities and new synthesis technology of the 1,2,4-triazolo[3,4-6]-1 ,3,4-thiadiazole derivatives.Chapter four The key synthon 3-[5'-aryl-2'-furanyl]-4-arnino-5-mercapto-s-triazole was prepared by two-step reaction derived from 5-aryl-2-furanylcarboxylic acid hydrazide under microwave irradiation. The reactions of 3-[5'-aryl-2'-furanyl]-4-amino-5-mercapto-s-triazole with arylcarboxylic acid, aryloxyacetic acid afford 8 new 3-(5'-m-nitrophenyl-2'-furanyl)-6-aryl-s-triazolo[3,4,-b]-l,3,4-thiadiazoles, 9 new 3-(5'-p-chlorophenyl-2'-furanyl) -6-aryloxy-s-triazolo[3,4-b]-l,3,4-thiadiazoles respectively. Considerable increase in reaction rate has been observed with improved yields under microwave irradiation.Chapter five Thioureas and thiosemicarbazides have extensive biological activities, such as antibactery, antihypertension, anticonvulsive, antidepressant, fugicide, insecticide, herbicide and plant growth regulator activities. Therefore they have been applied to many fields, for instance, medicine, agronomy, biology, etc. The new methods, new reagents andnew technologies of synthesis of these compounds are reviewed in this chapter.Chapter six An expeditious, high-yield and greener approach to substituted bis-thioureas and bis-thiosemicarbazides by grinding the mixture of 2,6-pyridine fonnyl dichloride with ammonium thiocyanate and arylamines or aroyl hydrazines catalyzed by PEG-400 at room temperature under solvent-free condition via one-pot procedure is described. We studied different affects of varies conditions (ratios, catalysts, grinding time) on the reactions and 18 new compounds are synthesized.In summary, all the above compounds have not been reported in the literature. Their structure are confirmed by elemental analysis, IR, 1H NMR. Compared with conventional methods, the conditions of these reactions are mild and the procedures of separation and purification of the desirable compounds are simple.