synthesized starting from 6-chloro- and 6,7-dichloro-4-(4-nitrophenyl)phthalazine (8). Routes to 1-unsubstituted (12) and 1-methyl (18) derivatives are different. Key intermediates 8 were prepared from 4-chloro- and 3,4-dichlorotoluene via ortho-formylbenzophenone derivatives 7.