Recent advances in the chemistry of pyridazine — an important representative of six-membered nitrogen heterocycles

Abstract

The review is devoted to recent advances in the chemistry of pyridazine — a six-membered heterocycle containing two nitrogen atoms in adjacent positions. The practical significance of title compounds is demonstrated and published data of the last decade devoted to them are considered systematically. The modern synthetic approaches to pyridazine derivatives are described in detail, analyzed and classified according to the precursor molecules involved in ring closure. The chemical properties of pyridazines are considered, including both reactions of the diazine ring and reactions of various substituents attached to the ring. Particular attention is given to the application of some pyridazine derivatives as pharmaceuticals, optical materials and ligands for catalysis. The bibliography includes 180 references.

Recent advances in versatile pyridazine-cored materials: principles, applications, and challenges

“…With many great achievements in the past decades, there are mainly two typical synthetic strategies (strategies I and II, Scheme 7) in the construction of PDs, including the cyclization of pyridazine-ring (PD-ring) (strategy I) and the modification of PDring (strategy II) from various precursory chemicals. On the one hand, the cyclization of PD-ring (strategy I) could be achieved by several methods, such as the Schiff-base condensation between hydrazine and diketones 122 /anhydrides 73 /aromatic ortho-diesters, 6 oxidative N-N coupling cyclization between hydroxylamine and dinitrogen tetroxide (N 2 O 4 ), 123 or t-BuOCl and aromatic diamines, 78 Diels-Alder cycloaddition between tetrazines and substituted acetylenes [124][125][126] or ethylenes, 57,127 [3+n] cycloaddition from azomethine ylides, 128 diazo-based cycloaddition 48,104 or quarternizative cyclization, 102 and photoactivation of pyridazine-N-Oxides (PD-N-Oxides). 129 On the other hand, the modification of PD-ring (strategy II) could be achieved by a huge number of C-C or C-N coupling or cyclization methods, including Suzuki reaction, Stille reaction, nucleophilic substitution, Sonogashira reaction, Aldol condensation, C-H activated direct arylation, Minisci reaction, Ullmann reaction, Buchwald-Hartwig reaction, and aroylation via wet chemistry, thermochemistry, photochemistry, and/or electrochemistry, which have been significantly investigated and/or summarized.…”

“…Owing to the outstanding biological features of PDs, such as bactericidal and anticancer actions (antitumor activity), their biological research and application in medical drugs and pesticides are very successful and have been reviewed. [48][49][50][51][52] Their progresses on materials have also been reviewed for many years. 7,53 To demonstrate the structureproperty-performance relationship of PDs, the accompanying principles, applications, challenges, and prospects, this review mainly focused on the classification of versatile PD-based materials and applications (Fig.…”

Assembly of Dihydropyridazines via [4+2] Cycloaddition of In Situ Generated Azoalkenes

“…In recent years, azoalkenes have been extensively used as efficient intermediates for the synthesis of various nitrogencontaining heterocycles, [9][10][11][12][13][14][15][16][17][18][19][20][21] and a broad range of transformations has been established using azoalkenes as suitable chemical handles. [22][23][24][25] In 2014, the Wang group disclosed a catalytic asymmetric inverse electron-demand aza-Diels-Alder reaction of labile electron-deficient azoalkenes with electronrich alkenes, providing pyridazines with excellent enantioselectivities. [26] In addition, Luo et al developed the [4 + 2] cycloaddition of azoalkenes to electron-neutral olefins in 2015.…”

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

“…Pyridazine is an important structural unit of many current drugs and agrochemicals (Figure ) . Numerous reviews on pyridazine chemistry have appeared over the past decades to demonstrate growing interest to this type of heterocycles . Pyridazin‐3(2 H )‐ones are one of the most important subtypes of this heterocyclic family highly attractive in modern drug discovery.…”