The Synthesize of 1-Ethyl-4-Oxy-7-Methyl-1,8-Naphththyridine-3-Carboxylic Acid

N-(6-methyl-2-pyridine)-amino-methylene-diethyl malonate was produced by condensation reaction of 2-amino-6-methyl pyridine with ethoxymethylene diethyl malonate under optimal conditions that n(2-amino-6-methyl pyridine)∶n(ethoxymethylene diethyl malonate) is 1∶1.3, reacting time 45 min and temperature 130 ℃,the yield of this reaction was 96%,which was 6% higher than that of literature.Then 4-oxy-7-methyl-1,8-naphththyridine-3-carboxylic acetate was synthesized by cyclization reaction in different heat carrier of diphenyl ether,paraffin oil and diethyl phthaltate in 250 ℃.The yields were 88.6%,56.3% and 61.2% respectively.The results show that diphenyl ether is the best heat carrier and reacting temperature has significant influence on production yield,while the ratio of raw materials and reacting time almost has no influence.Finally,1-ethyl-4-oxy-7-methyl-1,8-naphththyridine-3-carboxylic acid was produced by ethylation reaction using iodoethane,triethyl phosphate and diethyl carbonate and hydrolysis in alkaline condition.The yield of product is 92.6%,90.7% and 81.2% respectively.The influencing factors of synthetic reaction were studied and the advantages and disadvantages of using diethyl carbonate as the ethylization reagent were compared.The compounds were characterized with various spectroscopic methods.