Efficient mono- and bis-functionalization of 3,6-dichloropyridazine using (tmp)2Zn·2MgCl2·2LiCl

3,6-Dichloropyridazine undergoes a smooth metallation using (tmp)2Zn.2MgCl2.2LiCl. 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.