Synthesis of 3,6-Dichloro-4-(2-chloro-1,1-dimethylethyl)pyridazine

Article abstract of DOI:10.1021/jo00259a018

3,6-Dichloro-4-(2-chloro-1,1-dimethylethyl)pyridazine (3) is a systemic plant fungicide whose synthesis by several routes is described.Free-radical alkylations of 3,6-dichloropyridazine (1) gave either the 4-tert-butyl derivative 2 or the alcohol 3,6-dichloro-β,β-dimethyl-4-pyridazineethanol (24).Pyridazine (2) must be subjected to a free-radical chlorination, which resulted in other products, but alcohol 24 could be smoothly converted to 3.Alternatively, the pyridazine ring was constructed with the side chain preattached by utilizing lactone intermediates 10 or 18.The lactone 10 with hydrazine yielded the ether 11, and chlorination with ether cleavage proceeded to 3.Lactone 20 could not be transformed to 3.