2-(Trimethylsilyl)ethane thiol (0.33 mL, 2.1 mmol), Pd2(dba)3 (183.9 mg), Xantphos (231.4 mg) and DIPEA (0.296 mL) were added to a solution of (S)-3-(4-bromo-phenyl)-pyrrolidine-1-carboxylic acid tert-butyl ester (528 mg, 1.618 mmol) in 1,4-dioxane (7 mL) under nitrogen atmosphere. The reaction mixture was heated at 95-100° C. for 20 hours. After cooling to room temperature, a solution of 10% KHSO4/Na2SO4 was added and the mixture was extracted with EtOAc. The combined organic extracts were washed with brine, dried over Na2SO4, filtered, and evaporated under reduced pressure. The residue was purified via flash chromatography (hexane/EtOAc, 94/6) to give 616 mg (quantitative yield) of (S)-3-[4-(2-trimethylsilanyl-ethylsulfanyl)-phenyl]-pyrrolidine-1-carboxylic acid tert-butyl ester.
