PYRROLE STUDIES: 31. THE STRUCTURES OF POTENTIALLY TAUTOMERIC 1,2-DIHYDRO-6H-PYRROLOPYRIDAZINE-1-ONES AND 1,2,3,4-TETRAHYDRO-6H-PYRROLOPYRIDAZINE-1,4-DIONES

Article abstract of DOI:10.1016/0040-4020(84)85076-0

1,2-Dihydro-6H-pyrrolo<3,4-d>pyridazine-1-ones exist predominantly as such (10^4.47 : 1) in equilibrium with the 1-hydroxypyridazine form, whereas 1,2,3,4-tetrahydro-6H-pyrrolo<3,4-d>pyridazine-1,4-diones in equilibrium with the monohydroxy-oxo tautomeric forms are preferred by a factor of only ca. 100 : 1.It was not possible to determine the position of equilibrium between the 1-hydroxy-6H-pyrrolo<3,4-d>pyridazine-4-one and the 1,4-dihydroxy-6H-pyrrolo<3,4-d>pyridazine structures.