Ammonium Chloride → 2-methyl-3,4,5,6-tetrafluoropyridine N-oxide

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2,3,4,5,6-Pentafluoropyridine (commercially available from Aldich Chemical Co.) is oxidized to the corresponding N-oxide following the procedures described in Step 6 of Example 66. The 2,3,4,5,6-pentafluoropyridine N-oxide is treated at ambient temperature with one equivalent of methylmagnesium iodide in diethyl ether as described by F. Binns and H. Suschitsky in Chemical Communications, 750-751 (1970) and J Chem Soc (C), 1223-1231 (1771). The reaction mixture is treated with aqueous ammonium chloride and extracted with diethyl ether. The ether solution is dried over anhydrous magnesium sulfate, filtered and concentated under reduced pressure and the crude product is chromatographed on silica gel to afford 2-methyl-3,4,5,6-tetrafluoropyridine N-oxide (3,4,5,6-tetrafluoro-2-picoline). The N-oxide is then reduced to afford the title compound by the procedures described in Step 8 of Example 66.

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