Cascade synthesis of 2-pyridones using acrylamides and ketones (original) (raw)
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A Simple and Efficient Procedure for a 2-Pyridones Synthesis under Solvent-Free Conditions
International Journal of Organic Chemistry, 2011
This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit: http://www.elsevier.com/copyright Author's personal copy Efficient synthesis of new butenolides by subsequent reactions: application for the synthesis of original iminolactones, bis-iminolactones and bis-lactones
Synthesis of Multi Ring-Fused 2-Pyridones via an Acyl-Ketene Imine Cyclocondensation
Organic Letters, 2006
Experimental section General. All reactions were carried out under an inert atmosphere with dry solvents under anhydrous conditions, unless otherwise stated. 1,2-dichloroethane was distilled from calcium hydride and toluene distilled from sodium. TLC was performed on Silica Gel 60 F 254 (Merck) with detection by UV light and staining with a solution of Ce(SO 4) 2 4 H 2 O (2g), PMA (5g) and concentrated sulphuric acid (12 ml) in H 2 O (188 ml). Flash column chromatography (eluents given in brackets) was performed on silica gel (Matrex, 60 Å, 35-70 µm, Grace Amicon). The 1 H and 13 C NMR spectra were recorded on a Bruker DRX-400 for solutions in CDCl 3 [residual CHCl 3 (δ H 7.26 ppm) or CDCl 3 (δ C 77.0 ppm) as internal standard] or (CD 3) 2 SO [residual (CH 3) 2 SO (δ H 2.49 ppm) or (CD 3) 2 SO (δ C 40.0 ppm) as internal standard] at 298 K. Microwave reactions were performed using Smith Creator (Biotage, formerly Personal Chemistry) in a septa capped 2-5 mL SmithTM process vial with stirring. Procedure for the preparation of 2-pyridones (5a-d and 9a-c) using MWI: Meldrum's acid derivative 1 (1.65 mmol) was added to a stirred solution of imine 4 (0.55 mmol) (or imine 8 for preparation of 9a-c) solved in 1,2-dichloroethane (2.75 ml). Trifluoroacetic acid (42 µl, 0.55 mmol) was added and the mixture was irradiated at 160°C for 120s (fixed hold time, normal absortion level for compounds 5a-e and high absorption level for compounds 9a-c) and then cooled to room temperature. The resulting solution was diluted with CH 2 Cl 2 and washed with sat NaHCO 3 (aq), water and brine. The water phases were extracted with CH 2 Cl 2 and the combined organic extracts where dried with Na 2 SO 4 , filtered and concentrated. Purification by column chromatography gave 2pyridones (5a-e) and (9a-c). Procedure for the preparation of 2-pyridones using conventional heating: Meldrum's acid derivative 1 (1.5 mmol) was added to a stirred solution of imine 4 (0.5 mmol) solved in toluene (10 ml). Trifluoroacetic acid (0.5 mmol) was added and the solution was heated to reflux for 2h and then cooled to room temperature. The resulting solution was concentrated and then diluted with CH 2 Cl 2 and washed with sat NaHCO 3 (aq), water and brine. The water phases were extracted with CH 2 Cl 2 and the combined organic extracts where dried with Na 2 SO 4 , filtered and concentrated. Purification by column chromatography gave 2-pyridone (5c and 5d). Procedure for the preparation of 2-pyridones (9d and e) using MWI: Meldrum's acid derivative 7 (160 mg, 0.87 mmol) was added to a stirred solution of imine 8 (80mg, 0.44mmol) in 1,2-dichloroethane (2 ml). Trifluoroacetic acid (35 µl) was added and the mixture was irradiated at 160°C for 12min (normal absortion level) and then cooled to 50°C and an additional portion of Meldrum´s acid derivative 7 (80 mg, 0.44 mmol) was added. The mixture was then irradiated at 160°C for 11min (6min for compound 9d) and then cooled room temperature. The resulting solution was diluted with CHCl 3 and washed with sat NaHCO 3 (aq), and the water phase was extracted with CHCl 3 , the combined organic extracts where concentrated and purified by column chromatography [CHCl 3 :EtOAc] to give 2-pyridones (9 d and 9e). 1,3-oxazine-4-one (6). Meldrum's acid derivative 1a (1.8 mmol) was added to a stirred solution of imine 4a (0.6 mmol) in toluene (12 ml). Triethylamine (1.2 mmol) was added and the solution was
New methodology for the synthesis of 2-pyridones using basic Al2O3 as catalyst
A novel series of 2-pyridones derivs. have prepd. by new multi-component reaction (MCR) in excellent yields. The first step of this methodol. is the reaction of methylcetones 1a-c with N, N-dimethylformamide di-Me acetal under microwave irradn. affords the corresponding enaminone 2a-c which is the key intermediary of our synthetic method. The second step is one pot reaction of enaminones with Et 2-cyanoacetate in the presence of basic Al2O3 as catalyst without solvent. Structural assignments are based on spectroscopic data (IR, 1H NMR, 13C NMR, mass spectra). This method has the advantage of short time, high yields and being environmentally-friendly. [on SciFinder(R)]
A highly efficient multicomponent synthesis of pyridones and pyrimidones by a [2+2+2] strategy
Tetrahedron, 1999
The reaction of N-silylated iminoethers with 2-substituted acetyl chlorides yields activated 2-azadienes. These were shown to react with electron-deficient acetylenic dienophiles to yield pyridones. They also react with quinones to give the corresponding aromatized cycloadducts in good yields. The reaction of 2-azadienes with activated nitriles provided a very practical route towards polysubstituted pyrimidones. A multicomponent protocol is reported which combines a N-t-butyldimethylsilyl imineether, an acetyl chloride derivative and a dienophile in the presence of triethylamine without isolation of any intermediate. This provides an extremely practical and versatile route to various mono-and polycyclic azaaromatics with a predictable substitution pattern. Yields ranged from 43 % to 94 % for the complete sequence.
A green approach to the production of 2-pyridone derivatives promoted by infrared irradiation
An alternative is presented for promoting a reaction with infrared irradiation to obtain different 4-aryl-3-cyano-5-ethoxycarbonyl-6-methyl-2-pyridone derivatives 9a-k. The process was carried out with a green approach from the corresponding 4H-pyrans, using mild reaction conditions and infrared irradiation as the energy source. In the first stage, the reaction produced 1,2,3,4-tetrahydropyridin-2-one derivatives 8a-k, followed by an oxidative step to afford the target molecules in good yields. The structure of products 9a-k was confirmed by FT-IR, 1 H NMR and 13 C NMR spectroscopic techniques and X-ray diffraction. It was found that the efficiency of the reaction depends on the catalyst and the solvent, as well as on the aldehyde substituents.
A microwave approach to the synthesis of certain 4-substituted phenyl-6-phenyl-3-cyano-2-pyridones
Journal of the Serbian Chemical Society, 2014
A study of the synthesis of 4-(substituted phenyl)-6-phenyl-3-cyano-2-pyridones from ethyl 2-cyano-3-(substituted phenyl) acrylates and acetophenone is presented. The 2-pyridones were obtained using conventional as well as microwave synthesis under solvent and solvent-free conditions in domestic and laboratory microwave ovens. The structure of the obtained pyridones was confirmed by m.p., FT-IR, NMR and UV data.
Recent advances in synthesis of 2-pyridones: a key heterocycle is revisited
Journal of The Iranian Chemical Society, 2012
Owing to the versatile applications in different areas including biology, natural compounds, dyes, and fluorescent materials, the synthesis of 2-pyridone compounds is an important research field and has attracted a great deal of attention. In this review, 2-pyridones new synthetic methods are classified to tree classes including reactions based on pyridine rings, cyclization, and cycloaddition reactions.
ChemInform Abstract: Recent Advances in Synthesis of 2-Pyridones: A Key Heterocycle Is Revisited
ChemInform, 2014
The vancomycin family of glycopeptide antibiotics has been inspiring research in the field of synthetic chemistry since the 1980s. Recent studies have moved away from the focus of total synthesis into new territory: the design and evaluation of novel compounds based on the natural products which exhibit improved antibacterial activity. Modern approaches to drug synthesis draw together investigations into the nature of the binding environment, and innovative synthetic methodologies which provide solutions to the challenging structural features and stereochemistry associated with this intriguing class of compounds. New analogues, derivatives and dimers of the natural products, as well as recent successes in the total synthesis of the complestatins are described in this tutorial review, covering literature from the last decade.
Chemistry of Heterocyclic Compounds, 2015
The reaction of dialkyl ethoxymethylidenemalonates with arylamides of acetoacetic acid was studied for the purpose of creating a new method for the synthesis of substituted 2-pyridones containing a carbamoyl group. This reaction was shown to occur in the presence of triethylamine in ethanol solution at room temperature, forming mainly retro-Michael products, N,1-diaryl-5-acetyl-2-methyl-6-oxo-1,6dihydropyridine-3-carboxamides. Simultaneously, depending on the molar ratio of reagents, triethylammonium 5-acetyl-3-alkoxycarbonyl-1-aryl-6-oxo-1,6-dihydropyridin-2-olates were also formed at the same time. The results of this reaction can be explained by the different acidity of the acidic hydrogen atoms in Michael adduct.