... iV-substituted-2,3-diaminopyridines are intermediates in the synthesis of some fused heterocyclic systems as imid ... 13 and 15 can be distinguished by nmr on the basis of the characteristic chemical shifts of ... 3H, s, 0CH3) 1.57 (3H, t, J = 7.5 Hz, СН2-СЯ3), 4.74 (2H, q, J = 7.5 Hz ...