Potassium Carbonate → (Z)-4-bromo-1-methoxy-1,1,2-trifluoro-2-butene

Participants

Reaction Conditions

Reaction Steps

To a solution of 5.30 g (49.1 mmol) 1,1,2-trifluoro-1,3-butadiene in methanol (70 mL) at 0° C. in a round-bottom 250 mL flask was added 12.50 g of potassium carbonate (anhydrous powder). The flask was equipped with a magnetic stirrer, and the stirred contents cooled to ca. -70° C. Bromine (2.50 mL, 48.4 mmol) was slowly added to the -70° C. reaction mixture over two hours, and the resulting mixture stirred for further two hours at -50° C. At this point the contents of the flask were poured into a large excess of ice-water, and the liquid extracted twice with diethyl ether. The ether layers were combined, washed once with brine, then dried over anhydrous magnesium sulfate. Evaporation of solvent gave 7.50 g (70.2%) of (Z)-4-bromo-1-methoxy-1,1,2-trifluoro-2-butene as a clear liquid which was distilled at 74° C. (40 mm Hg). H-NMR (300 MHz, CDCl ): δ 3.62(3H, s), 3.98(2H, d, J=9 Hz), 5.76(1H, dt, J=9, 31 Hz). Mass spectrum: m/e=218,220 (M+). 19F-NMR (CDCl3): φ79.2(d, J=14.2 Hz) 126.5(dtt, J=31.0, 14.0, 2.4 Hz).

Provenance & Evidence