A mixture of 3-bromo-4-cyanophenylacetic acid (D134, 2.1 g, 7.00 mmol), 1-Boc 4-aminopiperidine (1.5 g, 7.49 mmol), EDC hydrochloride (1.5 g, 7.82 mmol), diisopropylethylamine (3.0 mL, 17.22 mmol), and DMF (25 mL) was stirred for 2 h at room temperature then diluted with ethyl acetate and washed with aqueous citric acid, aqueous sodium bicarbonate, water, and brine. Crystallisation from diethyl ether gave N-Boc 4-{[(2-bromo-4-cyanophenyl)acetyl]amino}piperidine (1.5 g, 2.84 mmol, 40.6% yield) as a white solid containing about 20% of N-Boc 4-{[(4-cyanophenyl)acetyl]amino}piperidine.
