Imidazole → 3-Ethynyl-imidazo[1,2-A]pyrazine

Participants

Reaction Conditions

Reaction Steps

To a solution of 3-((Trimethylsilyl)ethynyl)imidazo[1,2-a]pyrazine (0.15 g, 0.7 mmol) in 3.5 mL of THF was added 1.05 mL (1.05 mmol) of tetrabutylammonium fluoride (1.0M in THF) at ambient temperature. The solution was stirred for 15 min, concentrated, and the crude product purified by silica gel flash chromatography (eluted with 50% EtOAc/hexanes) to provide 0.078 g of product. 3-(1H-imidazol-1-yl)-5-(trifluoromethyl)aniline: A mixture of 3-Amino-5-bromobenzotrifluoride (4.0 g, 0.0167 mol), 8-hydroxy quinoline (0.362 g, 0.0025 mol), CuI (0.476 g, 0.025 mol), imidazole (1.36 g, 0.0199 mol), and potassium carbonate (2.52 g, 0.0183 mol) in 17 mL of DMSO (degassed with argon for ˜10 min) was heated at 120° C. under an atmosphere of argon for 15 h; the HPLC indicated no starting material. A 14% aqueous solution of ammonium hydroxide was added to the cooled mixture and this was stirred for 1 h at ambient temperature. Water (50 mL) and EtOAc (200 mL) were added and the aqueous layer was extracted with EtOAc (3×30 mL). The combined organic layers were dried over Na2SO4 and concentrated. The crude product was purified by silica gel flash chromatography (eluted with EtOAc/hexanes) to provide 2.51 g of product.

Provenance & Evidence