Abstract Nitration of amino-and diaminopyridines and-picolines led, in unexpected one-step reactions, to dinitrated derivatives. Dinitropicolines gave styrylpyridines, and 2-amino-6- hydroxy-3, 5-dinitropyridine was transformed by the thermolysis of its azido derivative into 5- amino-6-nitro [1, 2, 5] oxadiazolo [3, 4-b] pyridine. Using 1 H and 13 C nmr spectroscopy, azido-tetrazole tautomerism of 2-amino-6-azido-3, 5-dinitropyridine and intramolecular ...