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

Participants

Reaction Steps

To 100 ml of an anhydrous tetrahydrofuran solution of 7.56 g (40.6 mmol) of cis-2-t-butoxycarbonylcyclopropanecarboxylic acid was added 7.57 g (46.7 mmol) of 1,1-carbonyldiimidazole under cooling with ice. After stirring the mixture was stirred at room temperature for 2 hours, the solvent was evaporated under reduced pressure. To 50 ml of an anhydrous tetrahydrofuran solution of the resulting residue was added 80 ml of an anhydrous tetrahydrofuran solution of 101.5 mmol of previously prepared magnesium monoethyl malonate was added, followed by stirring overnight. After completion of the reaction, the solvent was removed by evaporation under reduced pressure, and ethyl acetate was added to the residue. 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 6.67 g (64.1%) of the titled compound as a yellow oily substance.

Provenance & Evidence