4-Nitrophenyl chloroformate was added to 1 mL of a solution of 7-((S)-5-hydroxymethyl-2-oxooxazolidin-3-yl)-3-(2-trifluoromethylphenyl)-2H-isoquinolin-1-one obtained in Step B of Example 1-13 (30 mg, 0.074 mmol) in pyridine, and the mixture was stirred at room temperature for six hours. Hexaethylene glycol monobenzyl ether (138 mg, 0.370 mmol) was added to the mixture which was then stirred at 60° C. for 14 hours. 1 N hydrochloric acid was added to the mixture, followed by extraction with ethyl acetate. The extract was washed with saturated saline and then dried over anhydrous sodium sulfate, and then the solvent was evaporated under reduced pressure. The resulting residue was purified by silica gel column chromatography (methylene chloride:methanol=50:1) to obtain 2-[2-(2-{2-[2-(2-benzyloxyethoxy)ethoxy]ethoxy}ethoxy)ethoxy]ethyl carbonate (S)-2-oxo-3-[1-oxo-3-(2-trifluoromethylphenyl)-1,2-dihydroisoquinolin-7-yl]-oxazolidin-5-ylmethyl ester (22 mg, yield: 37%) as a colorless oil. The product was deprotected by a method similar to that of Example 1-36 using a 10% Pd—C catalyst in a hydrogen atmosphere to synthesize the title compound.
