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.
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.