Methanol → 1-Dimethylamino-4-{N',N'-dimethyl-N-[2-(2,4,6-trimethyl-phenyl)-acetyl]-hydrazino}-piperidine-4-carboxylic acid methyl ester

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Reaction Steps

2.2 g (2,4,6-Trimethyl-phenyl)-acetic acid N-(4-cyano-1-dimethylamino-piperidin-4-yl)-N′,N′-dimethyl-hydrazide (from Step 3) is dissolved in 35 ml methanol and 8.7 g concentrated sulfuric acid is added dropwise. The mixture is heated to reflux for 18 hours, then cooled to room temperature, most of the solvent evaporated, then poured on ice, the pH adjusted to 7 by the addition of aqueous sodium hydroxide, and made alkaline by the addition of aqueous sodium bicarbonate. The mixture is then extracted with ethyl acetate, the organic layer dried over sodium sulfate and the solvent evaporated. The residue is chromatographed on silica gel with ethyl acetate/acetone (2:1) as a solvent, to give 1.55 g 1-Dimethylamino-4-{N′,N′-dimethyl-N-[2-(2,4,6-trimethyl-phenyl)-acetyl]-hydrazino}-piperidine-4-carboxylic acid methyl ester. 1H-NMR (CDCl3): 6.84 ppm (s, 2H), 3.70 ppm (s, 2H), 3.65 ppm (s, 3H), 3.05 ppm (s, 6H), 2.25 ppm (s, 3H), 2.21 ppm (s, 6H), 2.10-3.10 ppm (broad multiplets, total of 14H).

Provenance & Evidence