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A solution of 1,2,3-triazole (430 mg, 6.23 mmol), 2-chloro-3-nitrothiophene (1.02 g, 6.23 mmol) and potassium t-butoxide (838 mg, 7.48mmol) in DMF (20 mL) was stirred at 90 0C for 4 h, after which the reaction mixture was cooled to room temperature and diluted with Et2O. The solution was washed with brine and the organic phase was separated, dried (Na2SO4), filtered, concentrated under vacuum and purified by silica gel column chromatography (eluant hexane/ethyl acetate, 8/2 to 1/1) to give a 1 :1 mixture of 2-(3-nitrothiophen-2-yl)-2H- 1,2,3-triazole and l-(3-nitrothiophen-2-yl)-lH-l,2,3-triazole (1.08 g, 5.55 mol, 89%). Retention time (min) = 1.256 and 1.701, method [1], MS(ESI) 197.0 (M+Eta).The nitrothiophene and 10% palladium on carbon in ethyl acetate (e.g., 3 mL) was shaken under a hydrogen atmosphere (e.g., 40 psi) for about 2 h. The resulting suspension was filtered through a pad of diatomaceous earth and the filtrate was concentrated under vacuum.The title compound was prepared from 2-(3-nitrothiophen-2-yl)-2H- 1,2,3- triazole and l-(3-nitrothiophen-2-yl)-lH-l,2,3-triazole (514 mg, 2.61 mmol) according to protocol F to give a 1/1 mixture of 2-(2H-l,2,3-triazol-2-yl)thiophen-3-amine and 1-(1H-1,2,3- triazol-2-yl)thiophen-3 -amine (431 mg, 2.61 mmol, quantitative). Retention time (min) = 0.581 and 1.035, method [1], MS(ESI) 167.0 (M+Eta). |