In a 500 mL three-necked flask equipped with a thermometer, a constant-pressure dropping funnel with a drying tube, and a magnetic stirrer, lithium aluminum hydride (4.5 g, 0.12 mol) was suspended in 150 mL of dry ice-salt bath cooled of tetrahydrofuran, stirring vigorously. The N-isopropylbenzamide was dissolved in dry tetrahydrofuran (200 ml) and transferred to a dropping funnel. When the temperature of the system drops to below -5°C, slowly drop in the tetrahydrofuran solution dissolved with N-isopropylbenzamide, and the system releases heat immediately after dropping, and bubbles are released, adjust the dropping speed to make the reaction proceed smoothly. After the tetrahydrofuran solution of N-isopropylbenzamide was dripped, the reaction system was heated to reflux, and the reaction was maintained at reflux overnight. The reaction system was placed in an ice bath to cool down, and under vigorous stirring, a saturated ammonium chloride solution was slowly added. After the saturated ammonium chloride solution was continuously added, no bubbles were generated. The insoluble issue in the system was removed, and additionally ethyl acetate was used. The filter cake was cleansed countless times as well as additionally the filtrates were integrated. The filtrate was placed in a separatory network along with the layers were separated, and also the liquid layer was cleaned up with ethyl acetate till it was no longer positive by tender loving care. The natural layers were incorporated and also dried out over anhydrous magnesium sulfate over night. After drying out, anhydrous magnesium sulfate was filtered off, and likewise the filtrate was dried out under decreased pressure.Purified by ethyl acetate/dichloromethane 3:1 system column chromatography to obtain 13.6 g of pure pale yellow liquid, yield 87%
The title compound was prepared by reductive amination using a mixture of benzylamine (3 g, 28.00 mmol), acetone (2.3 ml, 31.32 mmol), MeOH (15 ml) and acetic acid (catalyst) to give N-benzyl as a colorless oil isopropylamine (1.8 g, 43.06%). 1H-NMR (500 MHz, CDCl3): δ 1.10 (d, J=6.5 Hz, 6H), 2.92 (Sep, J=6.5 Hz, 1H), 3.75 (s, 2H), 7.22 (m, 5H).