Hydrochloric Acid → 3-(4,4-difluoro-3-methylene-3,4-dihydro-2H-pyrrol-5-yl)-2-(trifluoromethyl)pyridine

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Reaction Steps

To a solution of tert-butyl {3,3-difluoro-2-methylene-4-oxo-4-[2-(trifluoromethyl)pyridin-3-yl]butyl}carbamate (3.25 g) in acetic acid (10 mL) was added dropwise concentrated hydrochloric acid (3 mL). The obtained mixture was stirred at room temperature for 2 hr, and concentrated under reduced pressure. Saturated aqueous sodium hydrogen carbonate solution was added to the residue, and the mixture was extracted with ethyl acetate. The extract was washed successively with saturated aqueous sodium hydrogen carbonate solution, water and saturated brine, dried over anhydrous magnesium sulfate, and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (eluent: hexane:ethyl acetate=3:1) to give the title compound as a yellow oil (yield 1.85 g, 83%).

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