Novel ortho- and peri-fused pyridazine ring systems

Abstract

By utilizing nucleophilic and electrophilic substitution reactions of 3(2 H)-pyridazinones, and application of various types of ring forming reactions, some novel polycyclic fused compounds containing pyrrolo[ b]-, pyrido[ b]-, pyrrolooxazino[ b]- or pyrrolopyrazino[ b]pyridazine skeletons were synthesized. From mechanistic point of view, structure–reactivity relationships were analyzed. In most cases, the cyclization reaction was strongly dependent on the substituents of the pyridazine ring.