[N:1]([CH2:4][C:5]([C:8]1[CH:13]=[CH:12][CH:11]=[CH:10][N:9]=1)([F:7])[F:6])=[N+:2]=[N-:3].C(C1C=C(SC2C=C(C)C(O)=C(C(C)(C)C)C=2)C=C(C)C=1[OH:24])(C)(C)C.C1C=C(Cl)C=C(C(OO)=O)C=1>ClCCCl>[N:1]([CH2:4][C:5]([C:8]1[CH:13]=[CH:12][CH:11]=[CH:10][N+:9]=1[O-:24])([F:7])[F:6])=[N+:2]=[N-:3]To the solution of 2-(2-azido-1,1-difluoro-ethyl)-pyridine (example 59c), 2.6 g, 14 mmol) and 3-tert-butyl-4-hydroxy-5-methylphenyl sulfide (0.5 g, 1.4 mmol) in 1,2-dichloroethane (40 mL) was added MCPBA (77%, 4.2 g, 18.2 mmol). The reaction mixture was stirred at 55° C. for 12 h. After cooling to room temperature, the reaction mixture was poured into a saturated aqueous NaHCO3/NaS2O3 solution (100 mL) and extracted with methylene chloride (3×100 mL). The combined organic extracts were dried over sodium sulfate, filtered, and concentrated in vacuo. Flash chromatography (Merck Silica gel 60, 70-230 mesh, 50%-100% ethyl acetate in hexane in 30 min) afforded 2-(2-azido-1,1-difluoro-ethyl)-pyridine N-oxide (2.7 g, 96%) as a clear oil. LC-MS m/e 201 (MH+).
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