Hydrochloric Acid → 4-(Piperidin-4-yl)indolin-2-one

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Reaction Steps

To a suspension of 4-pyridin-4-yl-1,3-dihydroindol-2-one acetic acid salt (5.50 g, 20.4 mmol) in methanol (160 mL), water (70 mL) and acetic acid (30 mL) was added concentrated hydrochloric acid (2 mL) followed by platinum(IV) oxide (360 mg). The mixture was hydrogenated for three days. It was then filtered through celite, which was washed with methanol. The filtrate was evaporated and dried under high vacuum. The residue was dissolved in methanol (500 mL) and treated with a basic resin (hydroxide form) at pH=9–10. The resin was removed by filtration and washed with methanol. The filtrate was evaporated and dried under high vacuum to give 4.2 g (96%) of 4-piperidin-4-yl-1,3-dihydroindol-2-one.

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