Under an atmosphere of argon, diphenylphosphoryl azide (8.20 g, 29 mmol) was added to a solution of 6-bromo-2-phenyl-imidazo[1,2-a]pyridine-7-carboxylic acid (9.16 g, 29 mmol) and triethylamine (5.8 g, 58 mmol) in tert-butanol (86 ml). The mixture was heated to reflux overnight, then cooled and diluted with ethyl acetate. The mixture was washed (NH4Cl satd.), and dried (Na2SO4). The title compound (2.75 g, 25%) was isolated from the residue by column chromatography (silica gel, heptane:ethyl acetate=100:0-50:50). MS (m/e)=388.1 [M+H+].
