A mixture of 2-(3,4,5-trimethoxy-phenyl)-5H-pyrrolo[2,3-b]pyrazine-7-carboxylic acid (70 mg, 0.2 mmol), isobutylamine (44 μL, 0.42 mmol), 1-hydroxybenzotriazole hydrate (56 mg, 0.41 mmol), and N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride (84 mg, 0.44 mmol) in DMF and CH2Cl2 was stirred at 70° C. overnight and partitioned between saturated NH4Cl and CH2Cl2. The aqueous layer was extracted with CH2Cl2 and the combined organic phases were washed with water, dried (Na2SO4), and concentrated. The residue was purified by preparative thin layer chromatography using 90:9.5:0.5 CH2Cl2:MeOH:concentrated aqueous NH4OH as eluant to afford 42 mg (50%) of 2-(3,4,5-trimethoxy-phenyl)-5H-pyrrolo[2,3-b]pyrazine-7-carboxylic acid isobutyl-amide as a pale yellow powder. M+H 403.
