1038393-19-9

1026201-45-5

General procedure for the synthesis of 8-bromoimidazo[1,2-a]pyridine-2-carboxylic acid from ethyl 8-bromoimidazo[1,2-a]pyridine-2-carboxylate: Intermediate 37 (2.02 g, 7.4 mmol) was dissolved in a solvent mixture of dioxane and water (16 mL dioxane/4 mL water) and the mixture was cooled in an ice bath. Subsequently, lithium hydroxide (LiOH, 355 mg, 14.8 mmol) was added and the resulting mixture was stirred and reacted at room temperature for 20 hours. After completion of the reaction, the volatile solvent was removed by distillation under reduced pressure. The mixture was cooled again in an ice bath and slowly acidified with aqueous 1 N hydrochloric acid (HCl) to pH 4. The precipitated solid was collected by filtration, washed with cold water (10 mL), and finally dried under vacuum to give Intermediate 39 (1.5 g, 88% yield).