Hydrogen Bromide → 1-(2-Fluorophenyl)-2-(4-methylthiophenyl)-2-bromo ethanone

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Reaction Steps

A 100 mL three necked round bottomed flask equipped with reflux condenser, magnetic stir bar, thermometer adapter, and constant pressure addition funnel was charged with 1-(2-fluorophenyl)-2-(4-methylthiophenyl)ethanone from Step 2, (4.36 g, 16.7 mmol), acetic acid (30 mL) and 33% HBr in acetic acid (0.5 mL). The solution was stirred and treated with bromine (17 mL, 16.8 mmol, 1.0M in acetic acid) from the addition funnel at such a rate that the bromine color was discharged rapidly, ca, 15 min. After an additional 50 minutes at room temperature, the solution was concentrated in vacuo to give a brown oil. The crude haloketone was dissolved in dichloromethane and washed with 1N NaHSO3, dried over anhydrous MgSO4, filtered and concentrated in vacuo to give 1-(2-fluorophenyl)-2-(4-methylthiophenyl)-2-bromo-ethanone as an oil that solidified upon standing (4.83 g, 85%): mp 58°-63° C. 1H NMR (CDCl3) 300 MHz 7.87 (td, J=7.6, 1.8Hz, 1H), 7.52 (m, 1H), 7.39 (d, J=8.3Hz, 2H), 7.27-7.03 (m, 4H), 6.34 (s, 1H), 2.45 (s, 3H). 19F NMR (CDCl3) -108.51 (m). Mass spectrum M+ =338.

Provenance & Evidence