Abstract:Michael addition of 2-aminopyridines with methylpropiolate to afforded the addition compound 1 a-g , which on further cyclisation at higher temperature in dowtherm-A to yield cyclised product 2 a-g , with respective yields depends on the nature of the substituents.Key words: Propionoic acid methyl ester, 2-aminopyridine and 3-(Pyridin-2-ylamino)-acrylic acid methyl ester.
“…We have synthesized these compounds by using carbamates. In continuation of our earlier reports [16][17][18][19][20][21][22][23][24] on synthesis of naphthyridine derivatives, we herein report a novel approach to synthesize 1-[3-(1,8-naphthyridin-2-yl)phenyl]-3-arylurea derivatives.…”
Asian Journal of Chemistry; Vol. 30, No. 4 (2018), [771][772][773][774] and only diagnostic and/or intense peaks are reported.
1H NMR spectra were recorded in DMSO-d 6 with a Varian Mercury plus 400 MHz instrument. Signals due to residual protonated solvent ( 1 H NMR) served as the internal standard. All the chemical shifts were presented in δ (ppm) using TMS as an internal standard. The 1 H NMR chemical shifts and coupling constants were determined assuming first-order behaviour. Mass spectra were recorded with a PE Sciex model API 3000 instrument. All the reactions were carried out under argon atmosphere.Biological assay: The synthesized compounds were dissolved in dimethyl sulphoxide at 30 µg/µL concentration (standard antibacterial drug, ampicilline was used as the reference antibiotic) and tested against Gram-negative strains of Escherichia coli, Klebsiella pneumonia and Gram-positive strains of Staphylococcus aureus and Bacillus subtilis using agar well diffusion method. Activities were determined by zones showing complete inhibition (mm). Growth inhibition was calculated with reference to positive control. All the samples were taken in triplicates.Synthesis of 2-(3-Nitrophenyl)-1,8-naphthyridine (3): To a stirred solution of 2-aminonicotinaldehyde (1 g, 8.18 mmol) in ethyl alcohol (20 mL) was added 1-(3-nitrophenyl)-ethanone (1.48 g, 9.00 mmol) and piperidine (2.09 g, 24.56 mmol) at room temperature and refluxed for 16 h. After completion of the reaction (monitored by TLC), the mixture was concentrated under reduced pressure and the crude product washed with 10 % dichloromethane in diethyl ether to afford 2-(3-nitrophenyl)-1,8-naphthyridine (3).Off Synthesis of 3-(1,8-naphthyridin-2-yl)aniline (4): To a stirred suspension of raney nickel (0.92 g, 10.75 mmol) in ethyl alcohol (20 mL) was added 2-(3-nitrophenyl)-1,8-naphthyridine (1 g, 3.58 mmol) and hydrazine hydrate (80 %) (0.54 g, 10.75 mmol) at room temperature and stirred at room temperature for 3 h. After completion of the reaction (monitored by TLC), the mixture was filtered through celite pad and the filtrate was concentrated under reduced pressure. The crude product was washed with 10 % dichloromethane in diethyl ether to afford 3-(1,8-naphthyridin-2-yl)aniline (4).IR ( δ 159. 7, 155.4, 153.7, 149.1, 138.8, 138.2, 137.1, 129.3, 121.8, 121.4, 119.5, 115.8, 115.2, 112.7; 222.19 (M+1).
Synthesis of phenyl phenylcarbamate derivatives (5a-q):To a stirred solution of anilines (3.29 mmol) in dichloromethane (6 mL) was added triethylamine (9.89 mmol) at room temperature and stirred at room temperature for 10 min and added aryl chloro formate (4.93 mmol) at 0 °C and stirred at room temperature for 2 h. The reaction mixture was concentrated under reduced pressure and the crude material washed with 10 % diethyl ether in pentane to afford the pure compounds. Without further purification used for next step. Yields of the products varied between 65 to 85 %.Preparation of novel 1-[3-(1,8-naphthyridin-2-yl)phenyl]-3-phenylurea derivatives (6a-6q): To a stirred ...
“…We have synthesized these compounds by using carbamates. In continuation of our earlier reports [16][17][18][19][20][21][22][23][24] on synthesis of naphthyridine derivatives, we herein report a novel approach to synthesize 1-[3-(1,8-naphthyridin-2-yl)phenyl]-3-arylurea derivatives.…”
Asian Journal of Chemistry; Vol. 30, No. 4 (2018), [771][772][773][774] and only diagnostic and/or intense peaks are reported.
1H NMR spectra were recorded in DMSO-d 6 with a Varian Mercury plus 400 MHz instrument. Signals due to residual protonated solvent ( 1 H NMR) served as the internal standard. All the chemical shifts were presented in δ (ppm) using TMS as an internal standard. The 1 H NMR chemical shifts and coupling constants were determined assuming first-order behaviour. Mass spectra were recorded with a PE Sciex model API 3000 instrument. All the reactions were carried out under argon atmosphere.Biological assay: The synthesized compounds were dissolved in dimethyl sulphoxide at 30 µg/µL concentration (standard antibacterial drug, ampicilline was used as the reference antibiotic) and tested against Gram-negative strains of Escherichia coli, Klebsiella pneumonia and Gram-positive strains of Staphylococcus aureus and Bacillus subtilis using agar well diffusion method. Activities were determined by zones showing complete inhibition (mm). Growth inhibition was calculated with reference to positive control. All the samples were taken in triplicates.Synthesis of 2-(3-Nitrophenyl)-1,8-naphthyridine (3): To a stirred solution of 2-aminonicotinaldehyde (1 g, 8.18 mmol) in ethyl alcohol (20 mL) was added 1-(3-nitrophenyl)-ethanone (1.48 g, 9.00 mmol) and piperidine (2.09 g, 24.56 mmol) at room temperature and refluxed for 16 h. After completion of the reaction (monitored by TLC), the mixture was concentrated under reduced pressure and the crude product washed with 10 % dichloromethane in diethyl ether to afford 2-(3-nitrophenyl)-1,8-naphthyridine (3).Off Synthesis of 3-(1,8-naphthyridin-2-yl)aniline (4): To a stirred suspension of raney nickel (0.92 g, 10.75 mmol) in ethyl alcohol (20 mL) was added 2-(3-nitrophenyl)-1,8-naphthyridine (1 g, 3.58 mmol) and hydrazine hydrate (80 %) (0.54 g, 10.75 mmol) at room temperature and stirred at room temperature for 3 h. After completion of the reaction (monitored by TLC), the mixture was filtered through celite pad and the filtrate was concentrated under reduced pressure. The crude product was washed with 10 % dichloromethane in diethyl ether to afford 3-(1,8-naphthyridin-2-yl)aniline (4).IR ( δ 159. 7, 155.4, 153.7, 149.1, 138.8, 138.2, 137.1, 129.3, 121.8, 121.4, 119.5, 115.8, 115.2, 112.7; 222.19 (M+1).
Synthesis of phenyl phenylcarbamate derivatives (5a-q):To a stirred solution of anilines (3.29 mmol) in dichloromethane (6 mL) was added triethylamine (9.89 mmol) at room temperature and stirred at room temperature for 10 min and added aryl chloro formate (4.93 mmol) at 0 °C and stirred at room temperature for 2 h. The reaction mixture was concentrated under reduced pressure and the crude material washed with 10 % diethyl ether in pentane to afford the pure compounds. Without further purification used for next step. Yields of the products varied between 65 to 85 %.Preparation of novel 1-[3-(1,8-naphthyridin-2-yl)phenyl]-3-phenylurea derivatives (6a-6q): To a stirred ...
“…This compound showed antibacterial activity and cytotoxicity comparable to that of ciprofloxacin . 2‐Cyclopropyl[1,8]naphthyridine‐3‐carboxylic acid (4‐phenyl‐2‐thioxo‐thiazol‐3‐yl)‐amides ( 37 ) also demonstrated moderate antibacterial activity against S. aureus and E. coli . …”
Section: Biological Properties Of 18‐naphthyridine Derivativesmentioning
confidence: 97%
“…This compound showed antibacterial activity and cytotoxicity comparable to that of ciprofloxacin [52]. 2-Cyclopropyl [1,8]naphthyridine-3-carboxylic acid (4-phenyl-2-thioxo-thiazol-3-yl)-amides (37) also demonstrated moderate antibacterial activity against S. aureus and E. coli [53]. Azetidinylquinolones 1,8-Naphthyridine derivatives with azetidine group have also been studied for antibacterial activity.…”
Section: Thiazolo Derivativesmentioning
confidence: 99%
“…In cell-based assays, active compounds exhibited inhibitory potential with EC 50 Anti-tuberculosis activity 1,8-Naphthyridines have also been investigated for antituberculosis potential. 4-Phenyl-1,8-naphthyridine derivatives (53) showed potential activity against Mycobacterium tuberculosis H37Rv [73]. To evaluate the antimycobacterial activity, a series of 1,8-naphthyridine derivatives with substitutions at the 2, 3, 4, and 7 positions were synthesized and assessed in vitro in accordance with an international program with the Tuberculosis Antimicrobial Acquisition and Coordinating Facility (TAACF).…”
The 1,8-naphthyridine group of compounds have gained special attention of researchers on account of their demonstrating a variety of interesting biological activities. A wide range of biological properties establishes them as potent scaffolds in therapeutic and medicinal research. The broad spectrum of activities primarily includes antimicrobial, antiviral, anticancer, anti-inflammatory, and analgesic activities. 1,8-Naphthyridine derivatives have also exhibited potential applications in neurological disorders such as Alzheimer's disease, multiple sclerosis, and depression. In addition, these synthetic derivatives have been found to possess activities such as anti-osteoporotic (α(v)β(3) antagonists), anti-allergic, antimalarial, gastric antisecretory, bronchodilator, anticonvulsant, anti-hypertensive, platelet aggregation inhibition, anti-oxidant, EGFR inhibition, protein kinase inhibition, ionotropic agent, β-3 antagonist, MDR modulator, adenosine receptor agonist, adrenoceptor antagonist, and pesticide activities. In spite of the widespread application of the 1,8-naphythyridine scaffolds, only a limited number of review articles are available till date. In this review, we attempt to compile and discuss the key data available in the literature for the multiple biological activities of 1,8-naphthyridine derivatives, in a chronological manner. This review compilation (with 199 references) may be helpful in understanding the diverse biological properties of 1,8-naphthyridines and provide insights into their mechanism of action. This may direct future research in the synthesis of new derivatives and exploring this scaffold for other possible biological activities.
“…However, the products were obtained in low yields of 21–28%. 17a Recently, 4-alkyl-6-aryl-1,3,5-triazin-2-amines were prepared by multicomponent reactions involving imidates, guanidines, and dimethylacetamide or dimethylpropanamide catalyzed by cesium carbonate. However, the required large amount of base, the high cost and the limited scope of commercially available imidates are undesirable aspects of this synthetic protocol.…”
Section: Table 1
Optimization Of Conditions For the Rea...mentioning
Two series of 4,6-disubstituted 1,3,5-triazin-2-amines were prepared by cesium carbonate-promoted cotrimerization of aromatic nitriles with guanidine and the reaction of (hetero)arylnitriles with N-acetylguanidine. The first series of 4,6-bis-(hetero)aryl-1,3,5-triazin-2-amines was synthesized in yields of 56-85% by adapting a traditional approach that starts from readily available substrates but requires strong and hard-to-handle bases as well as presents serious scope limitations. In this line, the method developed here used a mild base and overcame the scope limitation for p-substituted benzonitrile with electron-releasing group. The second series of 4-(hetero)aryl-6-methyl-1,3,5-triazin-2-amines comprises unsymmetrically substituted symmetrical triazines which were synthesized in yields of 58-75%. In summary, this work highlighted a synthetic method which tolerate broad range of substrates, including o- and p-substituted benzonitriles as well as heteroaromatic nitriles.
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