Synthesis of pyrazolo-annelated heterocyclic ring compounds such as pyrazolo[3,4-b]pyridines and pyrazolo[4′,3′:5,6]-pyrido[2,3-d] pyrimidines

Article abstract of DOI:10.1002/jhet.5570440210

(Chemical Equation Presented) A series of pyrazolo[3,4-b]pyridines has been synthesized by Friedlaender condensation of 5-amino-pyrazole-4-carbaldehyde 1 with active methylene compounds in basic medium. Pyrazolo[4′3′:5, 6]pyrido-[2,3-d]pyrimidines have be