Hydrogen Peroxide → Pyridine, 3-cyclopropyl-, 1-oxide

1.93 g of 3-cyclopropylpyridine (synthesized according to a method disclosed in Tetrahedron Lett. 2002, 39, 6987-6990) was dissolved in 15 mL of acetic acid, then 2.4 g of hydrogen peroxide solution (31%) was added thereto, and heated overnight under reflux. The reaction mixture was concentrated under reduced pressure, the obtained residue was dissolved in chloroform, and washed with a saturated aqueous solution of sodium hydrogen carbonate and water in the subsequent order. The organic layer was dried over anhydrous sodium sulfate. The insolubles were filtered, the filtrate was concentrated under reduced pressure, and 1.47 g of 3-cyclopropylpyridine 1-oxide [121-1] was obtained as a brown oily product.