[CH3:1][S:2](Cl)(=[O:4])=[O:3].[OH:6][CH2:7][CH2:8][CH2:9][N:10]([C:18]1[CH:23]=[CH:22][CH:21]=[CH:20][N+:19]=1[O-:24])[C:11]([O:13][C:14]([CH3:17])([CH3:16])[CH3:15])=[O:12].N1C=CC=CC=1>C(Cl)(Cl)Cl>[CH3:1][S:2]([O:6][CH2:7][CH2:8][CH2:9][N:10]([C:18]1[CH:23]=[CH:22][CH:21]=[CH:20][N+:19]=1[O-:24])[C:11]([O:13][C:14]([CH3:17])([CH3:16])[CH3:15])=[O:12])(=[O:4])=[O:3]Methanesulfonyl chloride (0.17 mL, 2.20 mmole) was added dropwise to a solution of 2-[N-(3-hydroxy-1-propyl)-N-(tert-butoxycarbonyl)amino]pyridine-N-oxide (0.50 g, 1.86 mmole) and pyridine (0.23 mL, 2.84 mmole) in CHCl3 (5 mL, dried over K2CO3) at 0° C. When complete by TLC, the reaction was diluted with CHCl3, washed with ice water, dried (Na2SO4), and concentrated. Silica gel chromatography (10% MeOH/CHCl3) gave the title compound (0.41 g, 64%) as a colorless oil: 1H NMR (250 MHz, CDCl3) δ8.25 (dd, J=6.0, 1.9 Hz, 1 H), 7.25 (m, 4 H), 4.35 (t, J=6.2 Hz, 2 H), 3.75 (t, J=6.6 Hz, 2 H), 3.00 (s, 3 H), 2.00 (m, 2 H), 1.40 (s, 9 H). Unchanged 2-[N-(3-hydroxy-1-propyl)-N-(tert-butoxycarbonyl)amino]pyridine-N-oxide (0.18 g, 36%) could also be recovered from the chromatographic purification.
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