Synthesis And Study Of The Heterocylic Small Molecules Compounds Owning Potential Bioactivity

1,3,4-thiadiazoles, 1,3,4-oxadiazoles and imidazo[2,l-b]-l,3,4-thiadiazoles derivatives have attracted extensively as they play an important role in many Pharmaceuticals, perhaps they arethe bioactive centers of the pharmaceuticals. Based on the previous work, some new approachs to obtaining the heterocyclic compounds were explored and developed. In this paper, we presente some results as follows:A series of 2,5-disubstituted-l,3,4-thiadiazoles have been synthesized by reaction of N-(2-Ben(b)Furoyl)-N'-aryloxymethylhydrazde (N-5-(4-chlorophenyl)-2-furoyl-N'-aryloxymethylhydrazde) and LR under microwave irradiation and solvent-free condition. The results show that this methond widens the using range of Lawesson's reagent in organic synthesis and it is an excellent synthesis method for 2,5-disubstituted-1,3,4-thiadiazoles.2,5-disubstituted-1,3,4-oxadiazoles are synthesized by cyclization reaction of N-(2-Ben(b)Furoyl)-N'-aryloxymethylhydrazde supported on acidic Al₂O₃ under microwave-assisted solvent-free conditions and the yields are very high. The procedure is simple and does not need any added catalyst or dehydrating reagent. A practical and rapid procedure is reported for the synthesis of a variety of 2,5-disubstituted-1,3,4-oxadiazolesA neat and rapid procedure is reported for the synthesis of a variety of 2-aryloxymethylene-6-benzylimidazo[2,1-b]-1,3,4-thiadiazoIe by condensation reaction of 2-amino-5-2-aryloxymethylene-1,3,4-thiadiazole withω-Bromoaceto-phenone in water under the microwave irradiation and yielded a series of novel compounds. The compounds were reacted continually with morpholine, formalin and acetic acid, synthesised a series of 2-aryloxymethylene-5-(morpholine-4-ylmethyl) -6-arylimidazo[2,l-b]-1,3,4-thiadiazoles were obtained. All of compound structures are characterized by elemental analyses, ER, ¹H NMR, ¹³C NMR and single crystal X-ray crystallography. In addition, the possible reaction mechanism was discussed.A number of N-aryl -N'-(5-(2-benzoruyl)-1,3,4-thiadiazole-2-yl)Ureas have been synthesized via the reactions of 2-amino-5-(2-benzoruyl)-1,3,4-thiadiazole with N-substituted trichloroacetamides by NaOH using one-pot procedures under microwave irradiation, the excellent yields can be obtained. The structures of compounds have been characterized by elemental analysis, IR and ¹H NMR.