A suspension (70 ml) of 1.81 g of 60% sodium hydride in N,N-dimethylformamide was cooled to −18° C. with ice-sodium chloride bath, and 21 ml of a solution of 8.67 g of 1-(p-toluoylamino)-2-propanone in N,N-dimethylformamide was added slowly. After 1-hour-stirring, 21 ml of a solution of 14.10 g of ethyl 2-(6-iodohexyloxy)-2-methylpropionate in N,N-dimethylformamide was added dropwise slowly. The bath was removed and the mixture was stirred for additional 18 hours at room temperature. The reaction solution was, after addition of ice-cold water, extracted with ethyl acetate, washed with water and brine sequentially, dried over anhydrous magnesium sulfate, and the solvent was distilled off under reduced pressure. The residue was purified by silica gel column chromatography (Wakogel® C-200, n-hexane: ethyl acetate=3:1) to provide 12.20 g of the objective compound as yellow crystals.
