Okuda, Shigenobu published the artcileThe constitution of matrine. XXVI. The constitution of dehydro-α-matrinidine, Safety of 4-Amino-2-picoline, the publication is Pharmaceutical Bulletin (1956), 257-61, database is CAplus.
cf. C.A. 49, 8316f. The decision between the 2 proposed structures of dehydro-α-matrinidine (I), upon which the structure of matrine depends, is based on spectrographic comparisons. Ultraviolet absorption maximum are recorded for: the degradation products of matrine, I, and the 2 bases C12H18N2, m. 111° and 190°, resp.; the 4-aminopyridine group of 4-H2N and 4-Et2N derivatives of C5H5N, and 5,7-dimethyl-1,2,3,4-tetrahydro-1,6-naphthyridine (II); the 3-aminopyridine group of 3-H2N (III) and 3-Me2N (IV) derivatives of C5H5N, and 2,4-dimethyl-5,6,7,8-tetrahydro-1,5-naphthyridine (V); the 2-aminopyridine group of the 2-H2N derivative of C5H5N, and 2,4-dimethyl-5,6,7,8-tetrahydro-1,8-naphthyridine. The solvents used were EtOH, 0.1N NaOH, 0.01N H2SO4, 50% H2SO4, and concentrated H2SO4. The spectra of 2,4-Me(H2N) and 2,6,4-Me2(H2N) derivatives of C5H5N were determined in EtOH only. Only II and IV were previously unknown. The synthesis of II will be reported later. Methylation of III with H2CO and HCO2H gave IV, b6 95°; picrate, m. 179-81°. Study of the spectra led to the following generalizations: the 3-aminopyridine group form their di-salts even in 50% H2SO2, whereas the matrine products and the 4-aminopyridine group show the same absorption in 50% as in 0.01N H3SO3; I absorbs at much shorter wave lengths than III in EtOH, 0.1N NaOH, and 0.01N H2SO2; C2H2N2 both have the same absorption in all solvents, very similar to that of II, and very different from that of V. It is concluded that all 3 matrine degradation compounds have the 4-aminopyridine skeleton, that I is 1-methyl-4,5,6,8,9,10-hexahydropyrido[3,4,5-ij]quinolizine, and that the C12H18N2 are Me derivatives of 8-propyl-1,2,3,4-tetrahydro-1,6-naphthyridine.
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, Safety of 4-Amino-2-picoline.
Referemce:
https://en.wikipedia.org/wiki/Pyridine,
Pyridine | C5H5N – PubChem