Staedeli, Werner published the artcileNitrogen-15 spectroscopy. Part 5. Nitrogen-15 NMR studies of aminopyridines, aminopyrimidines and of some diazine N-oxides, Formula: C4H6N4O, the publication is Helvetica Chimica Acta (1980), 63(2), 504-22, database is CAplus.
15N NMR spectra were obtained in neutral and acidic media for mono- and diaminopyridines, and mono-, di-, and triaminopyrimidines. Ring N shifts are discussed in terms of β-, χ-, and δ-substituent effects of amino and alkyl groups. Protonation states in trifluoroacetic acid and FSO3H solution and protonation effects on the 15N NMR spectra are determined A linear correlation is observed between amino substituent effects on the ring N-atom in aminopyridines and the corresponding 13C values in aminobenzenes, and, similarly, between 15N values in aminopyrimidines and 13C values in aminopyridines. One-bond 15N-H coupling constants for aminopyridines and aminopyrimidines are discussed in terms of conjugative interaction between NH2 groups and the ring system.
Helvetica Chimica Acta published new progress about 74638-76-9. 74638-76-9 belongs to pyrimidines, auxiliary class Pyrimidine, name is 2,4-Diaminopyrimidine-3-oxide, and the molecular formula is C11H24O3, Formula: C4H6N4O.
Referemce:
https://pubchem.ncbi.nlm.nih.gov/compound/Pyrimidine,
Pyrimidine – Wikipedia