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

Abstract

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 [a] P.

Diaza-1,3-butadienes as Useful Intermediate in Heterocycles Synthesis

“…The reaction of dichloro-substituted 1,2-diaza-1,3-dienes 76 with 2 equivalents of malononitrile allows access to highly functionalized 6-aminopyridazine derivatives 77 ( Scheme 15 ) [ 43 ]. In the first step of this reaction, a malononitrile anion is added to C-4 of the diazadiene 76 followed by β-elimination of HCl to form a new 1,2-diazadiene 78 .…”

Synthesis of Pyridazin‐3(2H)‐one Derivatives by the Reaction of CH‐Acids with Dichlorodiazadienes

“…Due to the presence of the electron‐withdrawing aza group, 4,4‐dichloro‐1,2‐diazabuta‐1,3‐dienes are highly reactive and useful electrophiles . The next subject of our research was the reactions of dichlorodiazadienes with C‐nucleophiles, in particular, with malononitrile . In this regard, it is worth noting separately the work of Fabi et al, in which pyridazines were synthesized by means of the reaction of 4‐chloro‐1,2‐diazabuta‐1,3‐dienes with active methylene compounds containing cyano and ketone groups .…”

Computational exploration of the copper(I)‐catalyzed conversion of hydrazones to dihalogenated vinyldiazene derivatives

“…A tedious multistep procedure was used to synthesize pyridazine moieties 12 . The utilization of halogenated VDs is more advantageous because functionalized pyridazine structures were synthesized quantitatively in a single step at room temperature 13,14 . VD is a hetero‐diene with boosted reactivity because of the strong electron‐withdrawing feature of the NN group compared to homo‐diene systems.…”

“…The addition of chlorine substituents to VDs opens up new opportunities to build diverse heterocyclic compounds and other substituted VD derivatives. For example, treatment of malononitrile with 2Cl‐VD yielded pyridazine nitrile derivatives, room temperature reaction between 2Cl‐VD resulted in pyridazin‐3(2H)‐ones formation, chlorine atoms were replaced with aril groups via Suzuki reaction, and several other functionalization of 2Cl‐VD can be conducted 13,15,16 . Treatment of 2Cl‐VD with NaN 3 at room temperature followed the formation of triazole derivatives 17 .…”

“…12 The utilization of halogenated VDs is more advantageous because functionalized pyridazine structures were synthesized quantitatively in a single step at room temperature. 13,14 VD is a hetero-diene with boosted reactivity because of the strong electron-withdrawing feature of the N N group compared to homo-diene systems. Some of us previously synthesized halogenated VD systems, which bear geminal chlorine atoms in the edge vinylic position according to the following reaction scheme to increase reactivity for the straightforward design of several heterocyclic compounds.…”