Diisopropyl azodicarboxylate (2.6 g) is added portionwise to a stirred solution of triphenylphosphine (3.4 g) in dry tetrahydrofuran (40 mL) at 0° C. under nitrogen. The reaction mixture is stirred at 0° C. for 15 minutes then treated with a solution of 2-fluoro-4-hydroxybenzonitrile (0.87 g) and t-butyl 3-(3-hydroxymethylphenyl)propionate (1.5 g) in dry tetrahydrofuran (10 mL) whilst maintaining the temperature at 0-5° C. Stirring is continued at this temperature for 1 hour when the reaction mixture is allowed to warm up to room temperature. The reaction mixture is evaporated to low bulk and partitioned between ethyl acetate (100 mL) and water (100 mL). The organic phase is washed with water (50 mL), dried over magnesium sulphate and evaporated. The residue is purified by flash chromatography on silica eluting with a mixture of cyclohexane and ethyl acetate (4:1 v/v). Fractions homogeneous in the required product are combined and evaporated to give tert-butyl 3-[3-(4-cyano-3-fluoro-phenoxymethyl)phenyl]propionate (0.3 g).
