[CH3:1][C:2]([CH3:8])([CH3:7])[C@H:3]([OH:6])[CH2:4][OH:5].N1C=CC=CC=1.[C:15]1([CH3:25])[CH:20]=[CH:19][C:18]([S:21](Cl)(=[O:23])=[O:22])=[CH:17][CH:16]=1>ClCCl>[OH:6][C@@H:3]([C:2]([CH3:8])([CH3:7])[CH3:1])[CH2:4][O:5][S:21]([C:18]1[CH:19]=[CH:20][C:15]([CH3:25])=[CH:16][CH:17]=1)(=[O:23])=[O:22]To a solution of (2S)-3,3-dimethyl-butane-1,2-diol (3.1 g, 26.3 mmol) in dichloromethane (25 ml) is added pyridine (4.3 ml, 52.6 mmol). To the mixture is then added dropwise a solution of 4-toluenesulfonyl chloride (5.0 g, 26.3 mmol) in dichloromethane (25 ml) at 0° C. The reaction mixture is warmed to room temperature and stirred for additional 16 h. The reaction mixture is diluted with dichloromethane (50 ml) and washed with 10% copper(II) sulfate solution (2×30 ml). The organic layer is dried over sodium sulfate and evaporated to get the crude product, which is purified by column chromatography (silica gel, 5% ethyl acetate/hexane) affording 4-methyl-benzenesulfonic acid [(2S)-2-hydroxy-3,3-dimethyl-butyl]ester (4.2 g, 14.4 mmol, 54%).
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