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The synthesis of pyridazino[4,5‐ d ] pyridazines, pyrazino [2,3‐ d ] pyridazines and a pyrimido [4,5‐ d ] pyridazine
Author(s) -
DiStefano Lorraine,
Castle Raymond N.
Publication year - 1968
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570050110
Subject(s) - pyridazine , chemistry , hydrazine (antidepressant) , hydrolysis , medicinal chemistry , stereochemistry , organic chemistry , chromatography
The synthetic chemistry of the relatively unknown pyridazino [4,5‐ d ]pyridazine ring system has been extended. 1,4‐Diaminopyridazino [4,5‐ d ]pyridazine (VIII) has been prepared by two routes, the most interesting of these being the one‐step conversion of 4,5‐dicyanopyridazine into VIII with hydrazine. Upon nitration VIII gave only the mononitramine (X). Attempts to prepare 1,4‐dichloropyridazino [4,5‐ d ]pyridazine gave only 4‐chloro‐2 H ‐pyridazino [4,5‐ d ]pyridazin‐1‐one (XII). Pyrimido [4,5‐ d ]pyridazine‐1,3‐dione (XIV) was prepared from pyridazine‐4,5‐dicarboxamide (IV). The hydrolysis of 5,8‐dichloropyrazino [2,3‐ d ]pyridazine (XV) gave 5‐chloropyrazino [2,3‐ d ]pyridazin‐8‐one (XVII) and likewise the ammonolysis of XV gave 5‐amino‐8‐chloropyrazino [2,3‐ d ]pyridazine (XX). As expected the hydrolysis of 5,8‐dibromo‐pyrazino [2,3‐ d ]pyridazine (XXI) gave 5‐bromopyrazino [2,3‐ d ]pyridazin‐8‐one (XXII). Attempted catalytic dechlorination of 5‐chloropyrazino [2,3‐ d ]pyridazin‐8‐one (XVII) gave 1,2,3,4‐tetrahydropyrazino [2,3‐ d ]pyridazin‐5‐one (XIX).