Put 717 mg (4.48 mmol) (+/−)-6-hydroxyheptanoic acid methyl ester under argon in 10 ml THF and cool to 0° C. Add 2.25 ml (4.48 mmol) of a 2 M solution of phosphazene base P2-tert.-butyl in THF and stir for a further 10 min at RT. Then cool to 0° C. again. Add 1.0 g (2.99 mmol) 4-chloro-5-(4-ethylphenyl)-6-phenylfuro[2,3-d]pyrimidine and continue stirring overnight at RT. Dilute with water, acidify with 10% aqueous citric acid solution and extract twice with ethyl acetate. Combine the ethyl acetate phases and wash once with satd. sodium chloride solution. Dry over magnesium sulphate, concentrate by evaporation and purify the residue by column chromatography on silica gel (solvent: cyclohexane/ethyl acetate 9:1). 640 mg (46.7% of theor.) of the target compound is obtained.
