Study On Base Mediated One Pot Synthesis Of Oxazole And Thiazole Derivatives Study On Base Metiaded One Pot Synthesis Of Oxazole And Thiazole Derivatives

Among the five member heterocyclics, oxazoles and thiazoles are two kinds of important nitrogen-containing compounds, which are usually acted as the important guide frames and core skeletons in organic syntheses. Their derivatives often possess high biological activities, thus result in their wide potential applications in medicinal and agrochemical fields as well as material science and so on. Owing to the simplicity of operation, avoiding cumbersome separation and purification of the intermediates, the "one-pot" procedure has been highlighted as one of the research frontiers in organic synthesis. This thesis includes three parts:(1) A base mediated "one-pot" synthesis of polysubstituted oxazoles from acylchlorides and2-bromoallylamine has been developed.(2) A base mediated multi-component "one-pot" synthesis of thiazole derivatives from isocyanate, primary amine and2,3-dibromopropene has been developed.(3) A base mediated multi-component "one-pot" synthesis of thiazole derivatives from isocyanate, primary amine and propargyl bromide has been developed. The research results are summerized as follows:1. A series of2,5-disubstituted oxazoles were synthesized via a KOH mediated one-pot reaction of acylchloride and2-bromoallylamine. By using acylchloride and2-bromoallylamine as starting materiels, triethylamine as acid binding agent, and dry DMSO as reaction solvent, the corresponding amides could readily be synthesized. The reaction mixture was added2.0equivalents of KOH and heated for a period time, the corresponding2,5-disubstituted oxazole was synthesized via elimination, cyclization and isomeration in one sequence. Our procedure has some advantages such as readily available cheap raw materials, metal-free and mild reaction condition, easy of operation, and higher yields.2. The intermediate which was afforded from the reaction of isocyanate with primary amine at room temperation reacted with2,3-dibromo-propene participated with K3PO4to offer thiazol-2-imine compound. The reaction combined nucleophilic substitution, elimination, cyclization and isomeration in one sequcence. Compared with literature methods, our method has the advantages such as mild conditions, wide applicability and higher yields.3. Mediated with K3PO4, a series of thiazole-2-imines were synthesized from isocyanates, primary amines and propargyl bromide. This "one- pot" synthetic procedure has some advantages such as higher efficiency, atomic economy and easy of operation.