Jm. Bakke et J. Riha, Synthesis of 3,4-diaminopyridine and imidazo[4,5-c]pyridines by nitration of 4-acylaminopyridines, J HETERO CH, 36(5), 1999, pp. 1143-1145
New methods for the preparation of 3,4-diaminopyridine (5) and imidazo[4,5-
c]pyridines 7a,7b based on direct nitration of 4-acylaminopyridines 3a, 3b
have been explored.