Sodiumtriacetoxyborohydride (2.59 g, 12.2 mmol) was added to a stirring suspension of 1-[3-(ethyloxy)-4-nitrophenyl]-4-piperidinone (2.15 g, 8.14 mmol), 1-(methylsulfonyl)piperazine (2.67 g, 16.3 mmol), acetic acid (0.70 mL, 12.2 mmol), and TEA (1.13 mL, 8.14 mmol) in 1,2-DCE (100 mL). The reaction was stirred at rt overnight then poured into saturated NaHCO3 (aq). The layers were separated and the aqueous layer was extracted with DCM. The combined organic layers were then dried, filtered and concentrated in vacuo. The residue was purified by flash chromatography to afford 1-{1-[3-(ethyloxy)-4-nitrophenyl]-4-piperidinyl}-4-(methylsulfonyl)piperazine (1.50 g, 45%). 1H NMR (400 MHz, DMSO-d6) δ ppm 7.86 (d, J=9.4 Hz, 1H), 6.58 (dd, J=9.5, 2.4 Hz, 1H), 6.50 (d, J=2.5 Hz, 1H), 4.18 (q, J=7.0 Hz, 2H), 3.99-4.08 (m, 2H), 3.04-3.12 (m, 4H), 2.90-2.99 (m, 2H), 2.86 (s, 3H), 2.55-2.61 (m, 4H), 1.77-1.88 (m, 2H), 1.39-1.50 (m, 2H), 1.35 (t, J=6.9 Hz, 3H).
