38666-30-7

426219-51-4

General procedure for the synthesis of 6,7-dihydroimidazo(1,5-a)pyridin-8(5H)-one from 5,6,7,8-tetrahydroimidazo[1,5-a]pyridine: 0.819 mmol of 5,6,7,8-tetrahydroimidazo[1,5-a]pyridine was dissolved in 3 mL of acetonitrile, and 2.457 mmol of potassium permanganate was added, and the reaction was carried out with vigorous stirring for 16 hours at room temperature. for 16 hours at room temperature with vigorous stirring. After completion of the reaction, the acetonitrile was completely removed by rotary evaporation. The residue was dissolved in 15 mL of 0.1 M HCl aqueous solution and kept in an ultrasonic bath at over 50 °C for 2 min. The resulting brown suspension was filtered and the filter cake was washed with 5 mL of 0.1 M HCl aqueous solution. The yellow filtrates were combined, alkalized with 2 M aqueous NaOH and extracted with dichloromethane (3 x 25 mL). The organic phases were combined, dried over sodium sulfate and concentrated by evaporation. From the residue, 0.617 mmol (75% crude yield) of 6,7-dihydroimidazo(1,5-a)pyridin-8(5H)-one was obtained as a yellow oil product. The purity of the crude product was 90% by NMR analysis. The properties of the product are consistent with the material already disclosed in WO 2002/040484.