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S ‐demethylation of nitrogen heterocycles
Author(s) -
Chen ShihFong,
Panzica Raymond P.
Publication year - 1981
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.5570180215
Subject(s) - chemistry , demethylation , pyridazine , dimethylformamide , annulation , sulfoxide , nitrogen , medicinal chemistry , sodium , dimethyl sulfoxide , organic chemistry , solvent , biochemistry , gene expression , dna methylation , gene , catalysis
When 3‐chloro‐4,5‐diaminopyridazine ( 2 ) was treated with sodium methylmercaptide in refluxing N,N ‐dimethylformamide, two heterocycles were formed and isolated, neither of which was the expected 3‐methylthio‐4,5‐diaminopyridazine ( 3 ). A thorough spectral analysis of these heterocycles showed them to be 4‐methylthioimidazo[4,5‐ d ]pyridazine ( 5 ) and imidazo[4,5‐ d ]pyridazine‐4‐thione ( 6 ). N,N ‐Dimethylformamide was found to provide the one carbon unit required for the formation of 5. The origin of 6 was shown to be a result of S ‐demethylation of 5. S ‐Demethylation of 3 could also be effected with sodium methylmercaptide in methyl sulfoxide without the occurrence of annulation. In methyl sulfoxide the process of demethylation was accelerated and occurred at lower temperature.