To a mixture of 4-ethoxy-3-fluorophenylboronic acid (0.86 g, 4.67 mmol), ligand TFP (0.144 g, 0.62 mmol), Pd2dba3 (0.29 g, 0.31 mmol), copper (I) thiophene-2-carboxylate (0.89 g, 4.7 mmol) was added a solution of 4-phenylsulfanylcarbonyl-piperidine-1-carboxylic acid tert-butyl ester (1.0 g, 3.11 mmol) in 10 mL of THF while purging with N2 at 50° C. After 18 hours the reaction mixture was diluted with ethyl acetate, filtered through celite then concentrated in vacuo. Purification by flash chromatography gave the title compound (0.95 g, 2.57 mmol). MS (ESI) m/z 352.0 (M+H+); HPLC (Novapak 150×3.9 mm C-18 column: mobile phase: 35-90% acetonitrile/water with 0.1% TFA, at 2 mL/min over 2 min.) t 1.42 min.
