2,4-Dimethylpyridine → 2,4-Dimethylpyridine 1-oxide

To a solution of 2,4-lutidine (2.0 g, 18.7 mmol) in methylene chloride (100 mL) was added 3-chloroperoxybenzoic acid (5.07 g, 29.4 mmol), which was stirred for 20 minutes at room temperature. A small amount of saturated aqueous sodium hydrogen sulfite solution was added to the reaction solution, and the organic layer was separated after vigorous stirring. This organic layer was washed with 5 N aqueous sodium hydroxide solution (5.9 mL), and dried over anhydrous magnesium sulfate. The solvent was evaporated under a reduced pressure to obtain the title compound (1.54 g, 66.9%). The title compound was used in the following reaction without being purified.