Tautomerism of Aza cycles: IV. Tautomeric structure of 4,5-dihydropyrazol- 5-one annelated on bond C3-C4 with piperidine cycle, and its three hydrochlorides
5-Methyl-2-phenyl-3,3a,4,5,6,7-hexahydro-2H-pyrazolo[4,3-c]pyridin-3-one has been synthesized and shown to exist in crystal as zwitterionic structure with the proton localized on the nitrogen atom in the piperidine ring and negative charge delocalized ove