2-(Dimethylamino)ethanol → Carbonic acid, 2-(dimethylamino)ethyl phenyl ester

A 391 mg (2.5 mmole) portion of phenyl chloroformate was added dropwise to a solution of 223 mg (2.5 mmole) of N,N-dimethylethanolamine and 253 mg (2.5 mmole) of triethylamine in 5 ml of methylene chloride under ice-cooling with stirring, followed by stirring further under ice-cooling for 10 minutes and then at room temperature for 30 minutes. The reaction solution was diluted with methylene chloride, and the solution was washed with 1% aqueous sodium hydrogencarbonate solution and dried over sodium sulfate. The solvent was distilled off, and there was obtained 465 mg of the crude 2-dimethylaminoethyl phenyl carbonate in the form of a colorless oil. 880 mg (2.2 mmole) of the compound as obtained in Example 80 was added to the compound, followed by warming at 90° C. for 2 hours. The reaction solution was subjected to separation and purification by chromatography on a column of silica gel (40 g). After impurities were removed with n-hexane-ethyl acetate (1:4) as an eluent, there was obtained the objective compound in the form of a colorless powder from the eluate of chloroform-methanol (10:1). Yield of 800 mg (71%).