Dimethyl Carbonate → 1-tert-Butyl 3-methyl 4-oxopiperidine-1,3-dicarboxylate

Participants

Reaction Conditions

Reaction Steps

To a suspension of 60% sodium hydride (3.5 g, 88 mMol) in dry toluene (50 mL), dimethyl carbonate (4.32 g, 48.0 mMol) was added dropwise in 0.5 h at room temperature under an atmosphere of nitrogen. After addition of a few drops of methanol, a solution of 1-tert-butoxycarbonyl-4-piperidone (4.8 g, 24 mMol) dissolved in dry toluene (20 mL) was added dropwise to the reaction mixture while stirring at 80° C. over 1 h. The reaction mixture was stirred for 3 h at the same temperature and then cooled to 0° C. (ice bath) and adjusted to pH 6-6.5 with acetic acid. The resulting cold mixture was diluted with water (10 mL) and adjusted to pH 8 with 5% sodium hydroxide solution. The toluene layer was separated and the aqueous layer was extracted with toluene (20 mL). The combined organic layer was dried over anhydrous sodium sulfate, and concentrated under reduced pressure The compound was dried in vacuum to give methyl-1-tert-butoxycarbonyl-4-oxo-3-piperidine carboxylate (5.0 g, 80%). The compound obtained was carried to next reaction without any further purification.

Provenance & Evidence