Arylidene-4,5-dihydropyridazines

A combination EIMS and X-ray study of [l,2,4]triazolo[l,2-b]- and [l,3,4]thiadiazolo[3,4-i>]phthalazines was undertaken [95JHC283], and X-ray crystal structure determinations of 5-(2-chlorobenzyl)-6-methyl-3(2W)-pyridazinone [95AX(C)1834], and on 6-benzyloxy-7,8-dihydro-8-phenyl-3-trifluoromethyl-r-triazolo[4,3-i>]pyridazine and its 5,6-dihydro-6-one derivative [95AX(C)1829] have been performed. Structures of some pharmacologically-active pyridazines previously reported as arylidene-4,5-dihydropyridazines need to be revised to those of aromatic pyridazine tautomers 6-8 based on a combination H NMR nOe and X-ray study [95AJC1601],... 

Dihydropyridazine-3,6-diones have reactive methylene groups, and they react with aromatic aldehydes to give 4,5-bis-arylidene derivatives (86JPR932 87JPR525). Pyridazines have been shown to undergo 1,3-dipolar cycloaddition with diazomethane [82H(I8)I75 88HI43I],... 

---