Synthesis of substituted pyridazino[4,5-c]pyridazines

Several pyridazino[4,5-c]pyridazines substituted in the 5- and 8-positions with hydroxyl, mercapto and amino groups and in the 3-position with a methyl group or a hydrogen atom have been prepared. In the course of this work five previously unreported pyridazine derivatives have also been synthesized.