Hydrochloric Acid → 1-(5-Bromothiophen-2-yl)-2-fluoroethan-1-one

To a stirred solution of 2-bromo-5-(2-fluoro-1,1-dimethoxy-ethyl)-thiophene (9.4 g, 35 mmol) in MeCN (100 mL) was added 10% aq. HCl (50 mL) at 20° C. and the reaction mixture was stirred at ° C. for 3 h. Solvent was removed in vacuo to afford a residue, which was partitioned between DCM and water, the aqueous layer was extracted with DCM. The combined organic layers were washed with water, sat aq. NaHCO3 and brine, dried over sodium sulfate and evaporated in vacuo to give a white solid. It was dissolved in minimum volume of DCM, and a large volume of hexane was added. After evaporation of most of the solvent, solid precipitated and was then collected with filtration, washed with hexane and dried under high vacuum to afford 1-(5-bromo-thiophen-2-yl)-2-fluoro-ethanone (6.52 g, 84%). 1H-NMR (CDCl3): δ 7.64 (d, 1H), 7.15 (d, 1H), 5.26 (d, 2H).