Neue Synthese 1-unsubstituierter 1H-Pyrazolo [3.4-b] pyridin-5-carbonsäureester

New Synthesis of Unknown 1-Unsubstituted 1H-Pyrazolo [3.4–b] pyridin-5-carboxylates A new synthesis of the unknown 1-unsubstituted 1H-pyrazolo [3.4-b] pyridine-5-carboxylates 6,11, 15 and 16 is described. Two different routes are employed. The one method uses pyridine derivative 1 , the other pyrazoles 7d–f as starting materials. The 1-position of the pyrazoles is protected by an easily cleavable heteroaryl-methyl moiety.