[Synthesis]
To a stirred solution of 2,3-dimethylpyridine (5.00 g, 46.7 mmol) in chloroform (100 mL) was added m-chloroperbenzoic acid (12.0 g, 77% max) in batches over a period of 5 min at 0 °C. The reaction mixture was continued to be stirred at 0 °C for 30 min, followed by slow warming to room temperature. After 16 hours of reaction, the mixture was concentrated to dryness, water (20 mL) was added and the pH was adjusted to 8 with saturated NaHCO3 solution. the mixture was concentrated again and the residue was extracted with dichloromethane/methanol (4:1). The organic phases were combined and concentrated to give a white solid. Purification by column chromatography (SiO2; eluent: dichloromethane/methanol, 9:1) afforded 2,3-dimethylpyridine-N-oxide as a white solid (4.80 g, 83% yield). The 2,3-dimethylpyridine-N-oxide (4.80 g, 39.0 mmol) was dissolved in acetic anhydride (50 mL) and heated to reflux overnight. After cooling, it was concentrated to dryness to give (2-acetoxymethyl)-3-methylpyridine as a brown oil (6.34 g). A mixture of crude (2-acetoxymethyl)-3-methylpyridine with K2CO3 (10.0 g, 72.4 mmol), methanol (60 mL) and water (30 mL) was stirred at room temperature overnight. The solid was removed by filtration and the filtrate was concentrated to dryness. After purification by column chromatography (SiO2; eluent: dichloromethane/methanol, 9:1), (2-hydroxymethyl)-3-methylpyridine was obtained as a light brown oil (2.86 g, 59% overall yield in two steps). The 1H NMR (CDCl3) data of (2-hydroxymethyl)-3-methylpyridine were as follows: δ 8.41 (d, J = 4.9 Hz, 1H), 7.48 (d, J = 7.5 Hz, 1H), 7.16 (dd, J = 4.9 and 7.5 Hz, 1H), 4.69 (s, 2H), 4.00 (br, 1H), 2.22 (s, 3H). |