Diethyl Ether → ethyl (1R,2R)-2-(4-bromophenyl)cyclopropanecarboxylate

Participants

Reaction Conditions

Reaction Steps

NaOtBu (3.23 g, 33.6 mmol) and 10 mL of dry DME were charged in round bottom flask previously inerted with nitrogen. Triethyl phosphonoacetate (7.7 mL, 38.64 mmol) was added at a rate such to maintain internal temperature below 30° C., about 30 minutes. The mixture was stirred until complete dissolution was observed, about 30 minutes. A solution of chiral 2-(4-bromophenyl)oxirane Enantiomer 1 (Intermediate 9 Enantiomer 1) (3.35 g, 16.8 mmol) in 6 mL of dry DME was added dropwise maintaining internal temperature between 20° C. and 30° C. The reaction mixture was stirred at 60° C. for 24 h. The temperature was increased to 70° C. and maintained at this temperature for further 6 h. Mixture was cooled to room temperature, taken up with 100 mL Et2O, cooled to 0° C. and poured in approx. 80 mL cold ss NH4Cl. The solution was diluted with approx. 20 mL water, the phases were separated and the aqueous one extracted with Et2O 2×100 mL. Combined organics were dried over Na2SO4 and evaporated to dryness to get crude title material that was purified by SiO2 flash chromatography (Horizon 65M) eluting with Et2O/n-hexane 5/95 to get after evaporation of the solvent, pure title material, 3.35 g as a colourless oil.

Provenance & Evidence