Step 4. Add methyl imidazo[1,2-A]pyrimidine-6-carboxylate (92 g, 356.5 mmol) and water (200 mL) to a round bottom flask. An aqueous 6N NaOH solution (2.5 eq.) was added slowly and dropwise with stirring at room temperature. The reaction mixture was continued to be stirred at room temperature for 1 hr and then cooled in an ice water bath, followed by the addition of concentrated hydrochloric acid to adjust the pH to 5-6. The reaction solution was concentrated under reduced pressure to about 150 mL (3/4 of the original volume) and cooled again in an ice water bath. The precipitate precipitated was collected by vacuum filtration, washed with cold water (50 mL) and dried to give imidazo[1,2-A]pyrimidine-6-carboxylic acid as an off-white solid (46 g, 79% yield). The product was characterized by 1H NMR (DMSO-d6, 400 MHz): δ 9.29 (d, J = 2.0Hz, 1H), 8.89 (d, J = 2.0Hz, 1H), 7.94 (s, 1H), 7.70 (s, 1H). Mass spectrum (ESI-): m/z 164.1 [M + H]+, 186.1 [M + Na]+.
![methyl imidazo[1,2-a]pyrimidine-6-carboxylate](/CAS/20180703/GIF/1083196-24-0.gif)
![iMidazo[1,2-a]pyriMidine-6-carboxylic acid](/CAS/20150408/GIF/944896-64-4.gif)