3-Aminopyrazolo[4, 3-c]pyridine-4, 6-dione as a precursor for novel pyrazolo[4, 5, 1-ij][1, 6]naphthyridines and pyrido[4', 3':3, 4]pyrazolo[1, 5-a]pyrimidines. Issue 13 (3rd July 2018)