Diethyl Ether → 1,3-Dichloro-3-fluoro-7-oxabicyclo[4.1.0]heptane

0.85 g (21.3 mmol) of sodium hydroxide pellets were added in three portions to 1.6 g (7.22 mmol) of pure alcohol 1f in suspension in 22 cm3 of distilled water at 15°-20° C. The reaction mixture was kept at room temperature for 1 h 15 min, 10 cm3 of ether were then added, stirring was continued for 5 min and then the aqueous phase was separated off and extracted with ether (5×25 cm3). The ether phases were combined, dried over magnesium sulfate and filtered, and the solvent was evaporated off. 1.28 g of a liquid, the epoxide 2e, were obtained; the crude yield was 96% (macrobore GC purity>98%).