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A large scale synthesis of 3‐chloro‐5‐methoxypyridazine
Author(s) -
Bryant Robert D.,
Kunng FenAnn,
South Michael S.
Publication year - 1995
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.5570320510
Subject(s) - chemistry , yield (engineering) , methoxide , derivative (finance) , catalysis , protecting group , nitrogen , group (periodic table) , organic chemistry , medicinal chemistry , combinatorial chemistry , materials science , alkyl , economics , financial economics , metallurgy
A large scale synthesis of 3‐chloro‐5‐methoxypyridazine was developed (18 moles) that relies on the protection of the pyridazinone nitrogen of 4,5‐dichloro‐3(2 H )‐pyridazinone as the tetrahydropyranyl derivative 2 . The 5‐chloro position of the protected pyridazinone was selectively displaced with methoxide to give 3 followed by catalytic hydrogenation of the 4‐chloro group to give 4. Removal of the protecting group with acid followed by phosphorous oxychloride treatment gave the target compound 6 in good yield. This route is superior to the previously described synthesis of this compound.