Sodium → Methyl 6,6-dimethylpiperidine-2,4-dione-3-carboxylate

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Reaction Steps

A solution of methyl 3-(ethoxycarbonylacetamido)-3-methylbutyrate (45 g) and sodium metal (4.22 g) in anhydrous methanol (450 ml) was heated at a reflux for 3 hours. The cooled mixture was evaporated under reduced pressure and the residue dissolved in water (200 ml). The aqueous solution was washed with ether (3×100 ml), acidified with 2N hydrochloric acid and the acidic mixture extracted with dichloromethane (3×100 ml). The combined extracts were washed with water (2×100 ml), dried over magnesium sulphate and evaporated under reduced pressure to give methyl 6,6-dimethylpiperidine-2,4-dione-3-carboxylate (26.3 g), mp 170°-172° C., as a cream crystalline solid.

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