917364-11-5

The general procedure for the synthesis of 5,6,7,8-tetrahydroimidazo[1,2-a]pyridine-2-carboxylic acid from imidazo[1,2-a]pyridine-2-carboxylic acid was carried out as follows: imidazo[1,2-a]pyridine-2-carboxylic acid (500 mg, 3.1 mmol) was dissolved in ethanol (20 mL) and platinum oxide (100 mg) was added as a catalyst. The reaction mixture was placed in an autoclave and hydrogenated under hydrogen pressure of 4 bar for overnight. Upon completion of the reaction, the catalyst was removed by filtration and the filtrate was concentrated to dryness under reduced pressure to afford the white solid product 5,6,7,8-tetrahydroimidazo[1,2-a]pyridine-2-carboxylic acid (500 mg, 97% yield). The structure of the product was confirmed by 1H NMR (400 MHz, DMSO-d6) with the following characteristic peaks: δ 7.63 (s, 1H), 3.96 (t, 2H), 2.70 (t, 2H), 1.85 (m, 4H).

[1] Patent: WO2007/108750, 2007, A1. Location in patent: Page/Page column 77
[2] Patent: WO2006/135627, 2006, A2. Location in patent: Page/Page column 140