Hydrochloric Acid → 8-Dimethylamino-1-methyl-3-(2,4,6-trimethyl-phenyl)-1,8-diaza-spiro[4.5]decane-2,4-dione

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Reaction Conditions

Reaction Steps

750 mg 1-Dimethylamino-4-{methyl-[2-(2,4,6-trimethyl-phenyl)-acetyl]-amino}-piperidine-4-carboxylic acid methyl ester (from Step 3) is dissolved in 35 ml N,N-dimethylformamide, cooled in an ice bath to 3° C., and 672 mg potassium t-butoxide is added. The mixture is allowed to warm to room temperature and stirred for 18 hours. Then half saturated aqueous ammonium chloride solution is added, and the pH adjusted to 5.5 by the addition of aqueous hydrochloric acid. The mixture is extracted with ethyl acetate, the organic layer washed with brine, dried over sodium sulfate, and the solvent evaporated. The residue is purified by chromatography on silica gel, with ethyl acetate as a solvent. Thus, 210 mg 8-Dimethylamino-1-methyl-3-(2,4,6-trimethyl-phenyl)-1,8-diaza-spiro[4.5]decane-2,4-dione is obtained as a solid, mp>195° C. 1H-NMR (CDCl3): 6.86 ppm (s, 2H), 3.12 ppm (m, 2H), 2.86 ppm (s, 3H), 2.84 ppm (m, 2H), 2.42 ppm (s, 6H), 2.30 ppm (m, 2H), 2.23 ppm (s, 3H), 2.17 ppm (s, 6H), 1.85 ppm (m, 2H).

Provenance & Evidence