Efficient mono- and bis-functionalization of 3,6-dichloropyridazine using (tmp)(2)Zn center dot 2MgCl(2)center dot 2LiCl

3,6-Dichloropyridazine undergoes a smooth metallation using (tmp)(2)Zn center dot 2MgCl(2)center dot 2LiCl. The resulting bis-organozinc species react with various electrophiles; subsequent functionalization via a second metallation proceeds readily; further reactions with hydrazine lead to highly substituted pyrazolo[3,4-c] pyridazines derivatives.