Construction of 6-Aminopyridazine Derivatives by the Reaction of Malononitrile with Dichloro-Substituted Diazadienes

The reactions of 4,4-dichloro-1,2-diazabuta-1,3-dienes with malononitrile resulted in an efficient approach to highly functionalized 6-aminopyridazine derivatives isolated in up to 98 %. The process was found to provide straightforward access to the interesting type of nitrogen-containing heterocycles with an exocyclic double bond. Furthermore, the possibility of subsequent functionalization of the obtained compounds via intramolecular cyclization was demonstrated. As a result, condensed azaheterocycles can be prepared very efficiently in one-pot and tandem versions. Finally, the influence of structural features of all synthesized compounds on their absorption characteristics in the UV/Vis-range is also investigated. © 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim