Study On The Synthesis Of N-heterocycle Compounds

This thesis contains four parts, which mainly described a novel, highly efficient synthesis of new 1, 4-dihydroquinoline derivatives via palladium- or iron-catalyzed intramolecular C-N cross-coupling reaction, and practical synthesie of various poly-substituted imidazoles and oxazoles by novel multi-component reactions.In the first part, Pd(OAc)2/DABCO(triethylenediamine) catalytic system was employed in the intramolecular C-N crossing coupling reaction for the first time. By the aid of this transformation, various 1, 4-dihydroquinoline derivatives were synthesized in high yields from o-halobenzaldehyde and a wide range ofβ-enaminones. DABCO showed more outstanding performance than other ligands in this reaction.In the second part, the ligand-free nano-Fe3O4 has been shown to be an active, stable and recyclable catalyst for the intramolecular C-N cross-coupling reaction for the first time. By using of this catalytic system, we have developed a novel and efficient method for the synthesis of various 1, 4-dihydroquinoline derivatives. Moreover, the strategy showed highly substrate generality and the novel Fe-catalyst is highly efficient for the inactive aryl chlorides and arylamine derivatives.In the third part, a convenient and highly efficient three-component protocol for the synthesis of various poly-substituted 2-(pyridin-2-yl)imidazoles from 2-cyanopyridine, corresponding aromatic aldehydes, and NH4OAc/primary amine has been developed. Notably, while the aliphatic primary amines were used as substrates, both di- and tri-substituted 2-(pyridin-2-yl)imidazoles were synthesized in one pot.In the fourth part, a series of poly-substituted oxazoles were successfully synthesized from 2-cyanopyridine and corresponding aromatic aldehydes. However, the activity of the novel reaction is not high enough, the deeper study on the reaction is currently in progress.