The synthesis of lmidazo[4,5-d] pyridazines. VI. v-Triazolo[4,5-d] pyridazines,pyrazino[ 2,3-d ] pyridazines and 7H-Imidazo [4,5-d] tetrazolo[ 1,5-b] pyridazine

Several pyridazines have been prepared as intermediates in the synthesis of monosubstituted imidazo4,5-d]pyridazines, monosubstituted v-triazoIo4,5-d]pyridazines and monosubstituted pyrazino 2,3d] pyridazines. The new ring system, 7H-imidazo4,5-d]tetrazolol,5-b] pyridazine (XIV) has been prepared unsubstituted. Furthermore, unsubstituted imidazo4,5-d]pyridazine (XI) has been prepared. Calculations for XI and XIV were made by approximate SCF LCAO-MO with CNSO II theory.