(1R,2S)-2-tert-Butoxycarbonylcyclopropanecarboxylic acid → Ethyl 3-(Cis-2-t-butoxycarbonylcyclopropyl)-3-oxopropionate

Participants

Reaction Steps

To 170 ml of an anhydrous tetrahydrofuran solution of 14.71 g (79.0 mmol) of (1R,2S)-2-t-butoxycarbonylcyclopropanecarboxylic acid was added 16.49 g (90.6 mmol) of 1,1-carbonyldiimidazole under cooling with ice, and the mixture was stirred at room temperature for 1.5 hours. The solvent was removed by evaporation under reduced pressure. To 60 ml of an anhydrous tetrahydrofuran solution of the resulting residue was added 150 ml of an anhydrous tetrahydrofuran solution of 197.5 mmol of previously prepared magnesium monoethyl malonate, followed by stirring for 3 days. After completion of the reaction, the solvent was evaporated under reduced pressure. Ethyl acetate was added to the residue, and the mixture was washed successively with 0.5N hydrochloric acid, a saturated sodium hydrogencarbonate aqueous solution, and a saturated sodium chloride aqueous solution. The organic layer was dried over anhydrous sodium sulfate, and the solvent was evaporated under reduced pressure. The residue was purified by silica gel column chromatography (hexane:ethyl acetate=7:3) to give 18.53 g (91.8%) of the title compound as a colorless oily substance.

Provenance & Evidence