A New Approach to the Synthesis of Polyfunctionally Substituted 1,8-Naphthyridin-2-one Derivatives from 6-Azidopyridones: A Novel Thermal Decomposition to 6-Aminopyridones
作者:Ramadan Ahmed Mekheimer
DOI:10.1055/s-2001-9749
日期:——
Azidation of the chloroaldehyde 2, which was obtained from the 6-hydroxy-2-pyridones 1, afforded the 6-azido-2-pyridones 3. Compound 3 can be converted to the corresponding 6-amino-2-pyridones 5, by the reaction with triphenylphosphine via phosphazenes and subsequent hydrolysis (Staudinger reaction). This obtained amine 5 reacts with ethyl cyanoacetate in an ethanolic solution containing piperidine to give 7-amino-6-carbethoxy-3-cyano-1,4-dimethyl-1,8-naphthyridin-2(1H)-one (9). Reaction of 9 with dimethylformamide dimethyl acetal, triethylorthoformate and hydrazine hydrate furnished the new 1,8-naphthyridin-2-ones 10, 11 and 12, respectively, in good yields. On the other hand, refluxing 9 with piperidine or morpholine, as secondary amines, did not afford the corresponding 1,8-naphthyridin-2-ones 13, but instead it undergoes a thermal decomposition under these reaction conditions to yield the unexpected 6-amino-3-cyano-1,4-dimethyl-pyridin-2(1H)-one (14).
将从 6-羟基-2-吡啶酮 1 中得到的氯醛 2 氮化,可得到 6-叠氮-2-吡啶酮 3。化合物 3 可以通过膦与三苯基膦反应,然后水解(施陶丁格反应),转化为相应的 6-氨基-2-吡啶酮 5。得到的胺 5 在含有哌啶的乙醇溶液中与氰乙酸乙酯反应,得到 7-氨基-6-甲乙氧基-3-氰基-1,4-二甲基-1,8-萘啶-2(1H)-酮(9)。将 9 与二甲基甲酰胺二甲基缩醛、正甲酸三乙酯和水合肼反应,分别得到新的 1,8-萘啶-2-酮 10、11 和 12,产率良好。另一方面,将 9 与作为仲胺的哌啶或吗啉一起回流,并不能得到相应的 1,8-萘啶-2-酮 13,相反,它在这些反应条件下发生热分解,得到了意想不到的 6-氨基-3-氰基-1,4-二甲基吡啶-2(1H)-酮 (14)。