Ethyl Acetate → 4-Methoxy-7-pyrazinyl-6-azaindol-3-yl-oxoacetic acid methyl ester

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Reaction Steps

To a mixture of AlCl3 (3.09 g, 23.2 mmol) in 20 mL of CH2Cl2-MeNO2 (4: 1) was added 4-methoxy-7-pyrazinyl-6-azaindole (0.525 g, 2.32 mmol) as a solid. To the resulting burgundy solution was added methyl oxalyl chloride (0.853 mL, 9.28 mmol) dropwise and then the mixture was stirred at room temperature for 1.5 h. The reaction mixture was then carefully poured into cold 20% aqueous ammonium acetate and EtOAc was added. The resulting emulsion was filtered and the residue was washed with additional EtOAc. The organic phase was separated and the aqueous phase was again extracted with EtOAc. The combined organic phase was dried (MgSO4) and evaporated to give 4-methoxy-7-pyrazinyl-6-azaindol-3-yl-oxoacetic acid methyl ester (0.494 g, 68%) as a brownish solid: LCMS m/e 313 (M+H)+. This material (0.456 g, 1.46 mmol) was taken up in 20 mL of MeOH, 1M K2CO3 (5.84 mL, 5.84 mmol) was added and the mixture was stirred at room temperature for 30 min. The solution was then diluted with water (4 mL) and concentrated in vacuo. The resulting aqueous solution was cooled at 0° C. and acidified to pH 1-2 with 6N HCl. This gave a bright yellow precipitate which was filtered, washed with cold 0.1N HCl and ether and dried in vacuo to give the title compound (0.309 g, 71%) as a yellow solid:

Provenance & Evidence