[CH3:1][O:2][C:3]1[CH:4]=[C:5]([N:12]2[CH2:17][CH2:16][CH:15]([CH2:18][CH2:19][S:20]([CH3:23])(=[O:22])=[O:21])[CH2:14][CH2:13]2)[CH:6]=[CH:7][C:8]=1[N+:9]([O-])=O.Cl[Sn]Cl>C1COCC1.Cl>[CH3:1][O:2][C:3]1[CH:4]=[C:5]([N:12]2[CH2:13][CH2:14][CH:15]([CH2:18][CH2:19][S:20]([CH3:23])(=[O:22])=[O:21])[CH2:16][CH2:17]2)[CH:6]=[CH:7][C:8]=1[NH2:9]To 1-[3-(methyloxy)-4-nitrophenyl]-4-[2-(methylsulfonyl)ethyl]piperidine (0.42 g, 1.3 mmol) in THF (60 mL) cooled to 0° C. was added SnCl2 (1.0 g, 5.4 mmol) dissolved in conc. HCl dropwise. The solution was stirred overnight at room temperature (TLC confirms consumption of starting material). The mixture was cooled to 0° C. and quenched with 6 N NaOH (25 mL). The solution was poured into EtOAc and H2O was washed with brine, back extracted with EtOAc, dried (MgSO4), filtered, and rotovaped down to give the title compound of step B (0.39 g, 1.3 mmol, 96%). 1H NMR (400 MHz, CDCl3) δ 1.18-1.29 (m, 2H), 1.31-1.43 (m, 1H), 1.57-1.65 (m, 2H), 1.70 (d, J=12.5 Hz, 2H), 2.37-2.43 (m, 2H), 2.92 (s, 3H), 3.07-3.14 (m, 2H), 3.34 (d, J=11.5 Hz, 2H), 3.69 (s, 3H), 4.16 (br. s., 2H), 6.25 (d, J=7.7 Hz, 1H), 6.40-6.48 (m, 2H).
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