General procedure for the synthesis of phenyl(pyrrol-3-yl)methanone hydrochloride from tert-butyl 3-benzoylpyrrolidine-1-carboxylate: Trifluoroacetic acid (10 mL) was added to a solution of tert-butyl 3-benzoylpyrrolidine-1-carboxylate (0.600 g, 2.18 mmol) in dichloromethane (40 mL), and the reaction mixture was stirred for 1 hour at room temperature. Upon completion of the reaction, the solvent was removed by concentration under reduced pressure to give a residue. This residue was dissolved in methanol (10 mL), followed by the addition of a solution of 1 M hydrochloric acid in ether (100 mL). The resulting slurry was stirred at room temperature for 1 h and then concentrated to dryness under reduced pressure to give phenyl(pyrrolidin-3-yl)methanone hydrochloride (0.435 g, 94% yield) as a tan solid. The mass spectrum (APCI positive ion mode) showed m/z 176 (100%) [M+H]+.
