Potassium Fluoride → 1-(5,6,7,8-Tetrahydroimidazo[1,2-a]pyridin-3-yl)ethanone

142 mg of the 3-bromo-5,6,7,8-tetrahydroimidazo[1,2-a]pyridine [44-2] was dissolved in 2.5 mL of toluene, 81.6 mg of tetrakis triphenylphosphine palladium (0) and 477 μL of tributyl(1-ethoxyvinyl)tin were added, and the mixture was stirred overnight at 120° C. The reaction mixture was cooled back to room temperature to add 10% aqueous solution of potassium fluoride, and extracted with ethyl acetate. The organic layer was washed with 10% aqueous solution of potassium fluoride and with saturated brine in the subsequent order, and then was dried over anhydrous sodium sulfate. The insolubles were filtered, the filtrate was concentrated under reduced pressure, and then the purification by silica gel column chromatography was carried out. The obtained compound was dissolved in 2 mL of chloroform, 200 μL of 10% hydrochloric acid-methanol solution was added, and the mixture was stirred for 40 minutes. The liquid was basified by adding a saturated aqueous solution of sodium hydrogen carbonate, and was extracted with chloroform. The organic layer was washed with saturated brine, and then dried over anhydrous sodium sulfate. The insolubles were filtered, the filtrate was concentrated under reduced pressure, and the obtained residue was purified by preparative thin-layer chromatography to obtain 62.2 mg of 1-(5,6,7,8-tetrahydroimidazo[1,2-a]pyridin-3-yl)ethanone [44-3] as a pale yellow oily product.