Categories: Synthesis of N-Heterocycles >
Synthesis of pyridazines
Recent Literature
A Lewis acid-mediated inverse electron demand Diels-Alder reaction between
3-monosubstituted s-tetrazine and silyl enol ethers provides
functionalized pyridazines, including 3-bromo-pyridazines, with high regiocontrol.
S. D. Schnell, J. A. González, J. Sklyaruk, A. Linden, K. Gademann, J. Org. Chem., 2021, 86,
12008-12023.
An unexpected C-C bond cleavage in the absence of metal enables an efficient
approach toward 3,6-diarylpyridazines and 6-arylpyridazin-3-ones from simple and
commercially available 1,3-dicarbonyl compounds and methyl ketones.
Q. Gao, Y. Zhu, M. Lian, M. Liu, J. Yuan, G. Yin, A. Wu, J. Org. Chem., 2012,
77, 9865-9870.
Cu(II)-catalyzed aerobic 6-endo-trig cyclizations provide 1,6-dihydropyridazines and pyridazines via the judicious choice of
reaction solvent. Whereas 1,6-dihydropyridazines were obtained in good yields
with MeCN as the reaction solvent, employment of AcOH directly afforded
pyridazines in good yields.
Z. Fan, Z. Pan, L. Huang, J. Cheng, J. Org. Chem., 2019, 84,
4236-4245.
A copper-promoted 6-endo-trig cyclization of readily available
β,γ-unsaturated hydrazones enables an efficient synthesis of a series of
1,6-dihydropyridazines with good yields, high functional group tolerance, and
remarkable regioselectivity under mild conditions. Importantly, the
1,6-dihydropyridazines can be efficiently converted to biologically important
pyridazines in the presence of NaOH.
Y.-Q. Guo, M.-N. Zhao, Z.-H. Ren, Z.-H. Guan, Org. Lett.,
2018, 20, 3337-3340.
A TBAI/K2S2O8-promoted [4 + 2] annulation of
ketene N,S-acetals, and N-tosylhydrazones provides a variety of
trisubstituted pyridazines in good yields. The method offers a broad substrate
scope and a good functional group tolerance.
Z. Liu, J. Lou, J. Xiao, Org. Lett., 2021, 23,
1606-1610.
An aza-Diels-Alder reaction of 1,2,3-triazines with
1-propynylamines enables a highly regioselective synthesis of
6-aryl-pyridazin-3-amines in high yields under neutral conditions. This reaction
offers good
functional group compatibility, broad
substrate scope and simple, metal-free, and neutral reaction conditions.
T. Kodama, I. Sasaki, H. Sugimura, J. Org. Chem., 2021, 86,
8926-8932.
The synthesis of pyridazinium salts was achieved from readily available
phenylazosulfonates in a single reaction step via the
formation of short-lived phenyldiazenes, which undergo a rapid
cycloaddition to furans to give the desired products after elimination of water.
S. Gradl, J. Köckenberger, J. Oppl, M. Schiller, M. R. Heinrich, J. Org. Chem., 2021, 86,
6228-6238.