18-Crown-6 → (E)-2-Bromo-6-(3-methoxystyryl)pyridine

Participants

Reaction Steps

To a solution of diethyl 3-methoxybenzylphosphonate (0.5 g, 1.94 mmol) in dimethylformamide (5 mL) at room temperature was added sodium methoxide (0.209 g, 3.87 mmol) and 18-Crown-6 (0.205 g, 0.77 mmol). After stirring at room temperature for 5 min, the reaction was cooled to 0° C. and treated with a solution of 6-bromopicolinaldehyde (0.432 g, 2.32 mmol) in dimethylformamide (2 mL) dropwise. When addition was complete, the ice bath was removed and the reaction stirred at room temperature for 1 h. The reaction was heated to 120° C. and held there for 2 h. The reaction was cooled to room temperature and stirred overnight. The resulting suspension was poured into water (70 mL) with vigorous stirring. The resulting suspension was extracted with diethyl ether (2×), washed with brine, dried over magnesium sulfate, and concentrated. The resulting residue was suspended in ethanol (ca. 10 ml). The resulting solution was placed in the freezer and held there for 3 h. The resulting precipitate was collected by filtration to give 150 mg (27%) as a white powder. 1H-NMR (CDCl3, 500 MHz) δ 7.61 (d, J=15.9, 1H), 7.49 (dd, J=7.6, 7.6, 1H), 7.22-7.36 (m, 3H), 7.16 (d, J=7.6, 1H), 7.10 (m, 1H), 7.07 (d, J=15.9, 1H), 6.87 (dd, J=8.2, 2.1, 1H), 3.84 (s, 3H). 13C-NMR (CDCl3, 126 MHz) δ 160.0, 157.1, 142.3, 138.9, 137.7, 134.4, 129.8, 126.7, 126.3, 120.7, 120.1, 114.8, 112.3, 55.4. Mass spec.: 290.01 (MH)+.

Provenance & Evidence