Trifluoroacetic acid → 1-Benzyl-3-(trifluoromethyl)pyrrolidine-3-carboxylic acid

2-(Trifluoromethyl)acrylic acid (2.48 g, 20 mmol) was dissolved in 30 mL of dry methylene chloride, a solution of 4.75 g (20 mmol) of N-benzyl-N-(methoxymethyl)-trimethylsilylmethylamine in 20 mL of dry methylene chloride was added dropwise under N2 at 0° C. To this solution was added 2 mL of TFA, and the solution was stirred for 2 hours at room temperature. The white precipitate was collected, washed and dried to give 3.22 g of the title compound.