Kato, Tetsuzo published the artcileSynthesis of methylpyridine derivatives. X. The Skraup reaction of 4-aminomethylpyridine 1-oxides, Formula: C6H8N2, the publication is Pharmaceutical Bulletin (1956), 178-81, database is CAplus and MEDLINE.
To prepare the rare 1,6-naphthyridine 6-oxide (I) derivatives, the Skraup reaction was applied to the easily available 4-amino-2,6-lutidine 1-oxide (II), 4-amino-3-picoline 1-oxide (III), 4-amino-2-picoline 1-oxide (IV), and 4-aminopyridine 1-oxide (V). Adding 2.75 g. concentrated H2SO4 dropwise to 1.38 g. II, 1.38 g. As2O5, and 3.68 g. glycerol, heating the mixture 3 hrs. in an oil bath at 155°, cooling, adding 50 cc. ice H2O, making alk. with Na2CO3, and extracting with 200 cc. CHCl3 yielded from the decolorized CHCl3 extract 0.15 g. 5,7-di-Me derivative (VI) of I, white needles, m. 127-32° (from C6H6 or Me2CO); picrate, yellow needles, m. 194-6° (from MeOH). Similar treatment gave (g. starting material, g. derivative of I formed, nature of crystals, m.p., and m.p. of picrate given): 3 g. III, 0.2 g. 8-Me (VII), white needles, 187-8.5° (from Me2CO), 170-2°; 12.4 g. IV, 0.85 g. 7(or 5)-Me (VIII), white needles, 158-9° (from C6H6, 216-19° (decomposition); 1.1 g. V, 0.09 g. I, pale yellow needles, 151° (from C6H6 or Me2CO), 185-6°. IV, m. 122-8° (picrate, m. 180°; HCl salt, m. 192°), and V, m. 229° (picrate, m. 201.5-2.0°), were prepared according to K. and H. (preceding abstract) from 4-nitro-2-picoline 1-oxide and 4-nitro-pyridine 1-oxide by catalytic reduction with 50% Pd-C in H2O in 92% and 88% yield, resp. The yields of all 4 derivatives of I were only 5-9%. Ultraviolet absorption curves were given for I-VIII.
Pharmaceutical Bulletin published new progress about 18437-58-6. 18437-58-6 belongs to pyridine-derivatives, auxiliary class Pyridine,Amine, name is 4-Amino-2-picoline, and the molecular formula is C6H8N2, Formula: C6H8N2.
Referemce:
https://en.wikipedia.org/wiki/Pyridine,
Pyridine | C5H5N – PubChem