7-Oxabicyclo[4.1.0]heptane-1-carboxylic acid ethyl ester

Synthesis

Aqueous Na2(EDTA) (1 × 10-4 M, 2.5 mL) and Bu4NHSO4 (10 mg, 0.03 mmol) were added to a solution of the olefifin (77 mg, 0.5 mmol) in acetonitrile (2.5 mL) with vigorous stirring at 0 °C. A mixture of oxone (1.5 g, 2.5 mmol) and NaHCO3 (0.65g, 7.75 mmol) was pulverized, and a small portion of this mixture was added to the reaction mixture to bring the pH to > 7. Then a solution of the ketone (38 mg, 0.125 mmol) in ACN (1.25 mL) was added. The rest of the Oxone and NaHCO3 was added to the reaction mixture portionwise over 4.5 h. On stirring for an additional 7.5 h at 0 °C and 12 h at room temperature, the resulting mixture was diluted with water and extracted with EtOAc. The combined extracts were washed with brine, dried (Na2SO4), fifiltered, concentrated, and purifified by flflash chromatography to give the epoxide as a colorless oil (65 mg, 77% yield, 93% ee by GC, absolute stereochemistry not determined unambiguously).

Reference: Wu, X.-Y.; She, X.; Shi Y. J. Am. Chem. Soc. 2002, 124, 8792– 8793.