In 10 ml of dry tetrahydrofuran was dissolved 744 mg (2.00 mmol) of 2-(benzyloxymethyl)-5-(3-chlorophenylthio)-4-isopropyl-1H-imidazole (16e), followed by addition of 410 mg (2.40 mmol) of allyl bromide, 96 mg (2.40 mmol) of sodium hydroxide and 5 mg (0.015 mg) of tetrabutylammoniumbromide at room temperature with stirring, and the mixture was stirred at room temperature for 3 hours. This reaction mixture was concentrated under reduced pressure, the residue was extracted with methylene chloride, the organic layer was washed with water arid dried over sodium sulfate. The solvent was concentrated under reduced pressure and the residual oil was fractionated by silica gel chromatography (ethyl acetate: methylene chloride=1:9). From the first fraction, 50 mg (yield 6.7%) of the objective position isomer (17g') was obtained, and then, 480 mg (yield 58%) of 1-allyl-2-benzyloxymethyl-5-(3-chlorophenylthio)-4-isopropyl-1H-imidazole (17g) was obtained.
