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

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Reaction Steps

Under an atmosphere of argon, a solution of 1.25 g 1-Dimethylamino-4-{N′,N′-dimethyl-N-[2-(2,4,6-trimethyl-phenyl)-acetyl]-hydrazino}-piperidine-4-carboxylic acid methyl ester in 10 ml dry N,N-dimethylformamide is cooled to 5° C., and treated with 1.04 g potassium t-butoxide. The mixture is stirred at ambient temperature for 18 hours, then poured into aqueous ammonium hydroxide, and the pH of the solution adjusted to 4.5 by the addition of aqueous hydrochloric acid. It is extracted three times with ethyl acetate, the organic layer separated, dried over sodium sulfate and evaporated. The residue is purified by chromatography on silica gel with cyclohexane/ethyl acetate (1:3) as a solvent, to yield 377 mg 1,8-Bis-dimethylamino-3-(2,4,6-trimethyl-phenyl)-1,8-diaza-spiro[4.5]decane-2,4-dione as a solid, mp 80-85° C. 1H-NMR (methanol-d4): 6.91 ppm (s, 2H), 3.18 ppm (m, 2H), 3.08 ppm (m, 2H), 2.93 ppm (s, 6H), 2.48 ppm (s, 6H), 2.35 ppm (m, 2H), 2.29 ppm (s, 3H), 2.14 ppm (s, 6H), 1.40 ppm (m, 2H).

Provenance & Evidence