Synthesis of Pyrrolo[1,2-b]pyridazine


Pyrrolo[1,2-b]pyridazine is a N-bridgehead aromatic heterocycle containing two nitrogen atoms, formally obtained by the condensation of pyridazine and pyrrole. The numbering of the atoms from the pyrrolo[1,2-b]pyridazine scaffold, also known in literature as 5-azaindolizine.  Although the synthesis and properties of the pyrrolo[1,2-b]pyridazines were reviewed in 1977 by Kuhla and Lombardino, the high interest in the synthetic pathways leading to such derivatives and their properties  has remained constant to this date. Thus, new papers were published concerning the synthesis and optical and biological properties of pyrrolo[1,2-b]pyridazine derivatives.