1,5-Naphthyridines and their n-oxides III. Synthesis and biological activity of some mono- and disubstituted 1,5-naphthyridines and their n-oxides
In order to search for biologically active compounds in the 1,5-naphthyridine series, we synthesized 2-mercaptoand 2-(4'-aminobenzenesulfonamido)-l,5naphthyridines and some of their 6-substituted derivatives. 2-(4'-Aminobenzenesulfonamido)-l,5-naphthyridine (I) was obtained by reaction of 2-amino-l,5naphthyridine with 4-carbomethoxyaminobenzenesulfonyl chloride in pyridine with subsequent saponification of the carbomethoxy group in the resulting 2-(4'carbomethoxyaminobenzenesulfonamido)-l,5-naphthyridine (II).
On the reactivity of 4-cyano-1,3-dichloro-7-methyl-5,6,7,8-tetrahydro-2,7-naphthyridine with several amines in different experimental conditions: monosubstitution, disubstitution, and a new unexpected rearrangement
Abstract The reactivity of 4-cyano-1,3-dichloro-7-methyl-5,6,7,8-tetrahydro-2,7-naphthyridine 1 with nucleophiles has been investigated. The different reactivity of the two chlorine atoms in 1 enabled us to obtain, by using different experimental conditions, the mono- and the di-amino-substituted derivatives of 5,6,7,8-tetrahydro-2,7-naphthyridines 2 and 3, respectively. Thus, by carrying out the reaction in a low-boiling solvent and in the presence of a quasi-stoichiometric amount of amine, the mono-substituted derivatives 2 were obtained, which under harsher conditions was transformed into the diamino derivatives 3 when using an excess of amine. During the synthesis of some diamino derivatives 3 a new rearrangement was observed with formation of 1-oxo derivatives of 3,4-dihydro-2,7-naphthyridines 4. The structure of the unexpected compounds 4 was confirmed by X-ray crystallography. A mechanism for the rearrangement is tentatively suggested.
Pteridine, XXIV1) Über die Isolierung und Struktur des orangeroten Schmetterlingspigmentes “Erythropterin”2)
Das orangerote Flugelpigment Erythropterin konnte erstmals in reiner Form aus Catopsilia argante isoliert und seine Konstitution durch alkalische Hydrolyse bzw. Methylierung als Xanthopteryl-(7)-brenztraubensaure erkannt werden. Auf Grund der physikalischen und chemischen Eigenschaften dieses Naturfarbstoffes mus die Seitenkette vollstandig enolisiert sein.