Study On The Synthesis Of Several Fused Aza-heterocyclic Compounds

N-containing heterocyclic compounds which have a wide range of applications in drug discovery, optical materials, chemical catalysis, energetic materials and many other fields are closely related to human’s life and development. Therefore, it is very necessary to explore its synthetic methods and study its synthetic process.In this paper, the synthesis of several bicyclic and tricyclic fused aza-heterocyclic compounds under different reaction systems or catalytic conditions were studied. Besides, the synthetic process of raw materials was optimized. Furthermore, the synthesis of some other tricyclic fused aza-heterocyclic compounds was explored.Bicyclic fused aza-heterocyclic compounds:Firstly, the reactions of 2,3-diaminop-yridine and 1,2-diketones were carried out in NH4CI-CH3OH at room temperature w-ith n(1,2-diketone)/n(2,3-diaminopyridine)=1.5 and n(NH4Cl)/n(2,3-diaminopyridine)= 5, generating 2,3-dimethyl-pyrido[2,3-b]pyrazine,2,3-diethyl-pyrido[2,3-b]pyrazine and 2,3-diphenyl-pyrido[2,3-b]pyrazine with yields of 85.0%, 82.0% and 84.9%, respective-ly. Secondly,2,3-diaminopyridine was reacted with orthoesters catalyzed by 10%mol phosphomolybdic acid at 35 ℃ with n(orthoesters)/n(2,3-diaminopyridine)=5, generating imidazopyridine and 2-methyl-pyridinoimidazole with yields of 84.0% and 78.9%, res-pectively. Pyridopyrazine was obtained with the yield of 91.0% with 4,5-dihydroxyi-midazolidin-2-one and 2,3-diaminopyridine refluxed in CH3CH2ONa/CH3CH2OH (pH =9). Thirdly, benzimidazoles were generated with good yields with equimolar arom-atic diamines and aromatic aldehydes reacted in the temperature-dependent biphasic system consisted of 5%mol [PEG1000mim2][FeCl4]2 ionic liquid and toluene (0.4mL/m mol substrate) at 80℃.Tricyclic fused aza-heterocyclic compounds:Firstly, the synthetic processes of T AB and TAP hydrochlorides were analyzed and optimized, and the total yields were 80.3% and 84.9%, respectively. Secondly, the reactions of TAB and 4,5-dihydroxyimi-dazolidin-2-one, TAP and orthoesters were studied. Pyrazinoquinoxaline were generate-d with the yield of 71.4% with TAB hydrochloride and 4,5-dihydroxyimidazolidin-2-one (2equiv) refluxed in the medium of CH3CH2ONa/CH3CH2OH under N2 atmosphe-re.2,6-dihydro-pyrido[2,3-b:5,6-b’] diimidazole and 2,6-dimethy-pyrido[2,3-b:5,6-b’]dii-midazole were obtained with yields of 68.7% and 66.5% with TAB hydrochloride a-nd orthoesters (5equiv) refluxed for 20h catalyzed by 5%mol phosphomolybdic acid. Thirdly, TAP hydrochloride was reacted with 3,4-hexanedione and 4,5-dihydroxyimida-zolidin-2-one respectively in the presence of acid binding agents, generating 2,3-diet-hyl-6,7-diamino-pyrido[2,3-b]pyrazine and 6,7-diamino-pyrido[2,3-b]pyrazine as main products through unilateral cyclization.