3- Amino-2,7-disubstituted 1,8-naphthyridines

Reaction of 2,4-dichloro-l,5-naphthyridine with ammonia (170°, 20 hr), hydrazine (100°, 16 hr), or aqueous hydrochloric acid (100°, 3 hr) was shown to yield the 2-amino- (47% yield) and 2-hydroxy-4-chloro derivatives (66% yield), but 2-hydrazino substitution (68% yield) was assumed. Disubstitution with ammonia (190°, 4 hr), hydrazine (100°, 48 hr), and ammonia-phenol (180°, 6 hr) occurred in high yield. Displacement of the 4-oxo group in 2,4-dioxo-l,5-naphthyridine occurs with aniline plus its hydrochloride (180°, 12 hr, 88% yield) to yield 429. Oxo groups in the 2- or 4-positions were... 

The Friedlander condensation of 2-aminonicotinaldehyde (221) with ketones and other active methylene compounds gives, as expected, good yields of the 2-substituted or 2,3-disubstituted 1,8-naphthyridines (222) (66JCS(C)315, 67JCS(C)1564, 71JCS(C)2991>. 2-Amino-... 

Some 1,3-dicarbonyl compounds, when condensed with 2,6-diaminopyridine, afford 2-amino-5,7-disubstituted l,8-naphthyridines.4a... 

Ring closure proceeded with 2,6-diaminopyridine, but instead of the 6-amino-2,4-disubstituted-pyrido[l,2-c<]pyrimidinium salts, 2-amino-5,7-di-substituted-l,8-naphthyridines were formed.4,11... 

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