650 mg (2.15 mmol) of 5-(5-chloro-2-thienyl)-1-(2-fluorobenzyl)-1,3-dihydro-2H-imidazol-2-one from Example 236A, 516 mg (4.21 mmol) of ethyl chloroacetate and 582 mg (4.21 mmol) of potassium carbonate are stirred in 12 ml acetonitrile for 7 hrs at 80° C. The reaction solution is diluted with ethyl acetate and washed three times with saturated sodium chloride solution. The organic phase is dried over sodium sulphate. After filtration from the drying agent, the filtrate is concentrated in vacuo. After purification by flash chromatography over silica gel (eluent: cyclohexane/ethyl acetate first 5:1, then 1:1), 610 mg (74% of theory) of the target compound are obtained.
