Regioselective palladium-catalyzed amination of 2-chloro-3-iodopyridine followed by a subsequent palladium-catalyzed amination leads to 2, 3-diaminopyridines. Treatment with triphosgene affords highly functionalized unsymmetrical imidazo [4, 5-b] pyridin-2-ones in just three synthetic steps. A two-step synthesis of pseudosymmetrically disubstituted imidazo [4, 5-b] pyridin-2-ones, 1, 4-disubstituted pyrido [2, 3-b] pyrazinediones, and 1, 3- ...