8-Hydroxy-l,7-naphthyridine

CN [2S-[2a,5a,6p(S )]]-6-[[[[(4-hydroxy-l,5-naphthyridin-3-yl)carbonyl]amino]phenylacetyl]amino]-3,3-dimethyl-7-oxo-4-thia-l-azabicyclo[3.2.0]heptane-2-carboxylic acid... 

Analysis of the ultraviolet spectra of 8- hydroxy -l,7-naphthyridine (57JCS5010) and of 4- hydroxy -l,5-naphthyridine (67MI21101) in alcoholic solvents indicates that the keto forms predominate. 

When the blocking group is other than a halogen atom or a keto group, only tars are formed. 8-Hydroxy- 1,7-naphthyridine61 is obtained from 3-amino-2-hydroxypyridine, and 1,5-naphthyridine is obtained from the 2-halo-3-aminopyridines when they are subjected to the Skraup reaction. 3-Aminopyridine 1-oxide aifords the parent 1,5-naphthyridine,62 and both 3-amino-6-hydroxypyridine and 3-amino-6-chloropyridine give 2-hydroxy-l,5-naphthyridine.63 Hart64 has applied the Skraup synthesis to 3-amino-4-hydroxypyridine and has obtained the expected 4-hydroxy-l,5-naphthyridine. 

The 2,3-disubstituted pyridines (29 and 31) were converted into 2-hydroxy- (30) and 2-methyl-4-hydroxy-l,5-naphthyridine (33), respectively,77 by the following sequences,... 

Common Name D-a-(4-Hydroxy-l,5-naphthyridine-3-carbonamido) benzylpenicillin sodium... 

Hydroxy-l,5-naphthyridine-3-carboxylic acid N-succinimide ester Sodium bicarbonate Sodium thiophenoxide Triethylamine... 

Stirring was further continued at room temperature for 2 hours. After cooling with ice, 1% sodium bicarbonate solution (100 ml) was added thereto. The precipitated crystals were collected by filtration, washed with water and dried over phosphorus pentoxide to give D-(a-4-hydroxy-l,5-naphthyridine-3-carboxamido)benzylpenicillin phenacyl ester (2.17 g). 

In the above procedure, the use of 4-hydroxy-l,5-naphthyridine-3-carbonyl chloride in place of 4-hydroxy-l,5-naphthyridine-3-carboxylic acid N-succinimide ester can also afford the same objective compound as above. The use of sodium thio-n-propoxide in place of sodium thiophenoxide can also give the objective compound in the form of the sodium salt. 

The mass spectra of 1,5-naphthyridin-2( 1 //)-one, 1,5-naphthyridin-4( 1 //)-one, and 4-hydroxy-l,5-naphthyridin-2(17f)-one have been compared with those of isomeric naphthyridinones.1253... 

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