* All experimental methods are cited from the reference, please refer to the original source for details. We do not guarantee the accuracy of the content in the reference.
4-Methoxyaniline (1.27 g) and 5-methoxymethylene-2,2-dimethyl-[1,3]dioxan-4,6-dione (1.82 g) were dissolved in 2-propanol (40 ml), and the solution was stirred at 50°C for 2 hr. The solvent was removed by distillation under the reduced pressure, and the residue was washed with ether to give 5-[(4-methoxy-phenylamino)-methylene]-2,2-dimethyl-[1,3]dio xan-4,6-dione (1.98 g, yield 73percent). 5-[(4-Methoxy-phenylamino)-methylene]-2,2-dimet hyl-[1,3]dioxan-4,6-dione (1.28 g) and biphenyl (5.2 g) were suspended in diphenyl ether (20 ml), and the suspension was stirred at 220°C for one hr. The reaction mixture as such was purified by column chromatography with a methanol-chloroform system to give 6-methoxy-1H-quinolin-4-one (398 mg, yield 49percent). 6-Methoxy-1H-quinolin-4-one (398 mg) was suspended in diisopropylethylamine (3 ml), phosphorus oxychloride (1 ml) was added to the suspension, and the mixture was stirred at 100°C for one hr. Water was added to the reaction mixture under ice cooling, and the aqueous layer was neutralized with an aqueous sodium hydrogencarbonate solution. The organic layer was extracted with ethyl acetate, and the ethyl acetate layer was washed with water and was dried over anhydrous sodium sulfate. The solvent was removed by distillation under the reduced pressure, and the residue was purified by column chromatography with an acetone-chloroform system to give 4-chloro-6-methoxyquinoline (375 mg, yield 42percent).
Reference:
[1] Synthetic Communications, 1985, vol. 15, # 2, p. 125 - 134
[2] Synlett, 2009, # 11, p. 1847 - 1851
[3] Synlett, 2007, # 14, p. 2205 - 2208
[4] Patent: EP1724268, 2006, A1, . Location in patent: Page/Page column 42
[5] Advanced Synthesis and Catalysis, 2010, vol. 352, # 14-15, p. 2445 - 2449
With N-ethyl-N,N-diisopropylamine; trichlorophosphate; at 100℃; for 1h;
4-Methoxyaniline (1.27 g) and 5-methoxymethylene-2,2-dimethyl-[1,3]dioxan-4,6-dione (1.82 g) were dissolved in 2-propanol (40 ml), and the solution was stirred at 50°C for 2 hr. The solvent was removed by distillation under the reduced pressure, and the residue was washed with ether to give 5-[(4-methoxy-phenylamino)-methylene]-2,2-dimethyl-[1,3]dio xan-4,6-dione (1.98 g, yield 73percent). 5-[(4-Methoxy-phenylamino)-methylene]-2,2-dimet hyl-[1,3]dioxan-4,6-dione (1.28 g) and biphenyl (5.2 g) were suspended in diphenyl ether (20 ml), and the suspension was stirred at 220°C for one hr. The reaction mixture as such was purified by column chromatography with a methanol-chloroform system to give 6-methoxy-1H-quinolin-4-one (398 mg, yield 49percent). 6-Methoxy-1H-quinolin-4-one (398 mg) was suspended in diisopropylethylamine (3 ml), phosphorus oxychloride (1 ml) was added to the suspension, and the mixture was stirred at 100°C for one hr. Water was added to the reaction mixture under ice cooling, and the aqueous layer was neutralized with an aqueous sodium hydrogencarbonate solution. The organic layer was extracted with ethyl acetate, and the ethyl acetate layer was washed with water and was dried over anhydrous sodium sulfate. The solvent was removed by distillation under the reduced pressure, and the residue was purified by column chromatography with an acetone-chloroform system to give 4-chloro-6-methoxyquinoline (375 mg, yield 42percent).