Categories: Synthesis of N-Heterocycles >
Synthesis of 2-pyridones
A mild Cu-catalyzed approach for the N-arylation of 2-pyridones with diaryliodonium salts proceeds readily at room temperature to provide N-arylpyridine-2-ones in very good yields.
S.-H. Jung, D.-B. Sung, C.-H. Park, W.-S. Kim, J. Org. Chem., 2016, 81, 7717-7724.
CuI-catalyzed coupling reactions of tetrabutylammonium pyridin-2-olates with aryl iodides allow an efficient synthesis of N-aryl pyridine-2-ones. This coupling reaction is mild, high-yielding, remarkably chemoselective (N- vs. O-arylation), and tolerates labile functional groups.
H. Zhang, B.-C. Chen, B. Wang, S. T. Chao, R. Zhao, N. Lim, B. Balasubramanian, Synthesis, 2008, 1523-1524.
A Co(III)-catalyzed redox-neutral annulation of benzamides and acrylamides with vinylene carbonate provides isoquinolinones and pyridinones in very good yields. This protocol tolerates diverse functional groups and substitution patterns.
X. Li, T. Huang, Y. Song, Y. Qi, L. Li, Y. Li, Q. Xiao, Y. Zhang, Org. Lett., 2020, 22, 5925-5930.
Formation of N-alkenyl alkynylamides by N-acylation of imines with alkynoyl chlorides and the subsequent cationic Au(I)/PPh3-catalyzed cycloisomerization allows a convergent and rapid assembly of substituted 2-pyridones.
H. Imase, K. Noguchi, M. Hirano, K. Tanaka, Org. Lett., 2008, 10, 3563-3566.
The chemo- and regioselective reaction of the Blaise intermediate, generated in situ from Reformatsky reagent and nitrile, with propiolates affords 2-pyridone derivatives in good to excellent yields.
Y. S. Chun, K. Y. Ryu, Y. O. Ko, J. Y. Hong, J. Hong, H. Shin, S.-g. Lee, J. Org. Chem., 2009, 74, 7556-7558.
Enamine formation of substituted keto-dioxinones followed by thermolysis and cyclization-aromatization enables the synthesis of various 6-substituted-4-hydroxy-2-pyridinones in good yields. The functionalized keto-dioxinones were constructed via a diethylzinc mediated crossed Claisen condensation reaction.
B. H. Patel, A. M. Mason, A. G. M. Barrett, Org. Lett., 2011, 13, 5156-5159.
A tandem condensation of propiolamide and cyclic β-keto methyl esters in water, followed by acid- or base-promoted intramolecular ring closure and decarboxylation enables an efficient synthesis of a 5,6-fused 2-pyridone ring system.
A. B. Smith, III, O. Atasoylu, D. C. Beshore, Synlett, 2009, 2643-2646.
Trapping of in situ generated active intermediate 1,4-oxazepines, formed from base-promoted 7-exo-dig cyclization reaction of N-propargyl enaminones, with alcohols/thiols and aldehydes provides 2-alkoxy/2-sulfenylpyridines and dihydrofuro[2,3-b]pyridines in good yields within 30 min at room temperature. This cascade reaction generates 1 equiv of H2O as the sole byproduct.
G. Cheng, L. Xue, Y. Weng, X. Cui, J. Org. Chem., 2017, 82, 9515-9524.