Iodopentafluoroethane → 5-(Perfluoroethyl)pyridin-2-amine

Beteiligte Stoffe

Reaktionsschritte

To a solution of 2-aminopyridine (25.0 g, 263 mmol) in a mixture of water (250 ml) and tert-butyl methyl ether (25 ml) was added, successively perfluoroethyl iodide (80 g, 38 ml, 315 mmol), sodium hydrosulfite (64.6 g, 26 ml, 315 mmol), sodium hydrogen carbonate (26.5 g, 315.6 mmol) and tetrabutyl ammonium hydrogen sulfate (“TBAHS”) (0.11 equiv., 9.92 g, 28.9 mmol). The reaction mixture was stirred at ambient temperature for 16 h. The mixture was filtered and the filtrate was extracted twice with tert-butyl methyl ether. The combined organic phases were washed successively with water, aqueous hydrochloric acid (1N) and brine, dried over sodium sulfate and concentrated. The residue was purified by flash chromatography (AcOEt/cyclohexane) to give 5-(1,1,2,2,2-pentafluoroethyl)pyridin-2-amine in 7% yield. 1H NMR (400 MHz, CDCl3) 8.23 (d, 1H), 7.61 (d, 1H), 6.72 (m, 1H), 5.04 (sb, 2H, NH2) ppm. The major by-product was 3,5-bis(1,1,2,2,2-pentafluoroethyl)pyridin-2-amine.

Herkunft & Nachweise