[Synthesis]
Example 1a Synthesis of 6-methyl-2-(4-methylphenyl)imidazo[1,2-a]pyridine-3-acetic acid: zolpidem (8.0 g, 26.0 mmol) was dissolved in 6N hydrochloric acid (80 mL) at 0°C and protected by argon with magnetic stirring. The reaction mixture was heated to reflux for 18 hours. Upon completion of the reaction, the mixture was cooled to 0 °C and the pH was adjusted to 6.5 by slowly adding 20% sodium hydroxide solution.The precipitated white solid was collected by vacuum filtration to afford the target product, 6-methyl-2-(4-methylphenyl)imidazo[1,2-a]pyridine-3-acetic acid (6.9 g, 94% yield), as a white solid.1H NMR (DMSO-d6) δ 2.30 ( s, 3H), 2.35 (s, 3H), 3.94 (s, 2H), 7.10 (d, J = 9.1 Hz, 1H), 7.25 (d, J = 7.8 Hz, 2H), 7.48 (d, J = 9.1 Hz, 1H), 7.72 (d, J = 7.8 Hz, 2H), 8.18 (s, 1H).13C NMR (100 MHz, DMSO-d6) δ 18.4, 21.4, 30.8, 114.8, 116.6, 121.6, 122.9, 127.9, 128.2, 129.8, 132.4, 137.3, 143.0, 143.5, 171.8. |