Triphenylphosphine → 5-((1S)-2-(t-butyldimethylsiloxy)-1-methyl-ethoxy)-3-(4-methylthiophenoxy)-benzoic acid methyl ester

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Reaction Steps

After adding 1.40 g (7.40 mmol) of (2R)-1-(t-butyldimethylsiloxy)-2-hydroxypropane and 2.00 g (7.40 mmol) of triphenylphosphine to a solution of 1.20 g (4.13 mmol) of the 5-hydroxy-3-(4-methylthiophenoxy)benzoic acid methyl ester obtained in Production Example 1 in tetrahydrofuran (10 ml), 3.20 ml (7.40 mmol) of diethyl azodicarboxylate was added while cooling on ice, and the mixture was stirred at room temperature for 2 hours. Water was added to the reaction mixture, extraction was performed with acetic acid ethyl ester, and then the organic layer was washed with brine, dried and concentrated under reduced pressure. The obtained residue was purified by silica gel column chromatography (hexane:acetic acid ethyl ester=95:5) to obtain 1.63 g of 5-((1S)-2-(t-butyldimethylsiloxy)-1-methyl-ethoxy)-3-(4-methylthiophenoxy)-benzoic acid methyl ester (yield: 95%) as a colorless oil. After adding 2.06 g (12.0 mmol) of m-chloroperbenzoic acid to a solution of 1.84 g (3.97 mmol) of the obtained ester compound in chloroform (40 ml) while cooling on ice, the reaction mixture was stirred for 0.5 hour while cooling on ice. Aqueous sodium thiosulfate was added to the reaction mixture, and the organic layer was washed with saturated aqueous sodium hydrogencarbonate and brine, dried, and concentrated under reduced pressure to obtain a crude sulfone compound.

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