To a mixture of chloroform (3.5 ml) and toluene (0.75 ml) is added (1R*,5S*)-1-methyl-8-oxa-bicyclo[3.2.1]octane-2,4-dione (0.25 g, 1.62 mmol) and N,N-dimethylaminopyridine (0.99 g, 8.11 mmol) under a nitrogen atmosphere with stirring. To this reaction mixture is then added 4′-chloro-4-methylbiphenyl-3-yllead triacetate (1.05 g, 1.78 mmol) in one portion, then the mixture heated at 80° C. for 1-2 hours. The reaction mixture is cooled to room temperature, acidified with dilute aqueous hydrochloric acid then filtered through diatomaceous earth to remove inorganic residues (subsequent washing with dichloromethane). Aqueous fractions are extracted with dichloromethane (2×10 ml), then all organic fractions are combined, dried over sodium sulfate and concentrated under vacuum to give crude product which is purified by flash chromatography (hexane/ethyl acetate) to give (1R*,5S*)-3-(4′-chloro-4-methylbiphenyl-3-yl)-1-methyl-8-oxabicyclo[3.2.1]octane-2,4-dione (0.240 g) as a white solid.
