Rac-cis-7-Oxa-3-aza-bicyclo[4.1.0]heptane-3-carboxylic acid tert-butyl ester (1 g, 5 mmol) was solvated in dioxane (5 mL), 2-Chloro-4-Fluorophenol was added (1.471 g, 10 mmol) and sodium hydroxide (0.401 g, 10 mmol). After 20 hours refluxing, the mixture was cooled, ammonium chloride was added and the mixture extracted three times with ethyl acetate. The combined organic phases were dried with magnesium sulfate and concentrated under vacuum. After a flash chromatography with heptane/ethyl acetate 1:1 to 1:2 heptane/ethyl acetate a solid the title compound was obtained as solid (0.778 g, 45% yield). MS (m/e): 404.5 (M+AcO−).
