General procedure for the synthesis of 4-amino-3-methylbenzonitrile from 3-methyl-4-nitrobenzonitrile: 9.89 g (61 mmol, 1 equiv.) of 3-methyl-4-nitrobenzonitrile was added to a stirred 100 mL tetrahydrofuran (THF) solution at room temperature. Subsequently, 1 g of 10% palladium carbon catalyst was added. Next, 25 mL of methanol was added. The reaction system was placed in a hydrogenation unit and the reaction was carried out at a hydrogen pressure of 50 psi. When hydrogen consumption was no longer observed, the reaction was stopped and filtered through diatomaceous earth to remove the catalyst. The product was purified by column chromatography using a 1:1 mixture of hexane and dichloromethane as the mobile phase. 7.5 g of 4-amino-3-methylbenzonitrile in beige powder form was finally obtained in 93% yield. The 1H-NMR (DMSO-d6) data of the product were as follows: δ 2.27 (3H, s), 6.06 (2H, s), 6.41 (1H, d), 6.46 (1H, s), 7.30 (1H, d).
