Synthesis and structure of 7-alkyl-5-amino-6,7,8,9-tetrahydroisoxazolo5,4-c-2,7-naphthyridines

A series of new heterocyclic systems: isoxazolo5,4- c -2,7-naphthyridines, were synthesized based on the 1,3-dichloro-2,7-naphthyridines. The reaction of 7-substituted 1,3-dichloro-5,6,7,8-tetrahydro-2,7-naphthyridine-4‑carbonitrile compounds with cyclic amines provided 3-chloro-7-methyl-1-(cyclicamine-1-yl)-5,6,7,8-tetrahydro-2,7-naphthyridine-4‑carbonitriles. These compounds in turn were reacted with hydroxylamine hydrochloride in the basic conditions and as a result of intramolecular condensation the desired reaction products, isoxazolo5,4- c -2,7-naphthyridines, were formed. The structure of obtained isoxazolo5,4- c -2,7-naphthyridines besides the spectroscopic data was confirmed by the X-ray analysis. The antimicrobial activity of the synthesized compounds has been evaluated. The biological tests evidenced that compounds showed modest antimicrobial activity. • Highlights is manuscript is synthesis of unique, previously unknown in the literature new heterocyclic systems: Isoxazolo5,4- c -2,7-naphthyridines, as potentially biologically active compounds. • This systems simultaneously containing in their structure isoxazolo5,4- b pyridine and 2,7-naphthyridine fragments. • It is well known from the literature that these two heterocyclic systems have both synthetic and medicinal significance. • Since isoxazolo5,4- c -2,7-naphthyridines are new heterocyclic systems, their structure was also confirmed by the X-ray analysis. • Thus, it can be stated that the manuscript has a great theoretical novelty and practical importance.