Trifluoroacetic acid → 3-Carboxy-5-(1,1-dimethylethyl)-alpha-(3-mercaptopropyl)-benzenepropanoic acid

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Reaction Steps

To a solution of 2-(3-tert-butyl-5-methoxycarbonyl-benzyl)-5-[(triphenylmethyl)thio]pentanoic acid XII (5.5 g, 9.7 mmol) in dichloromethane (30 mL) were added triisopropylsilane (2.4 mL, 11.6 mmol) and trifluoroacetic acid (10 mL), and the mixture was stirred at room temperature for 10 minutes. The solvent was removed under reduced pressure and the crude material was purified by silica gel chromatography (1% AcOH in Hexanes/EtOAc, 4:1) to afford 3-carboxy-5-(1,1-dimethylethyl)-alpha-(3-mercaptopropyl)-benzenepropanoic acid 49 (1.7 g, 5.3 mmol, 55%) as a white solid: 1H NMR (CD3OD) δ 1.3 (s, 9H), 1.5-1.8 (m, 4H), 2.4 (m, 2H), 2.6-2.7 (m, 1H), 2.8-2.9 (m, 1H), 2.9-3.0 (m, 1H), 7.5 (s, 1H), 7.7 (s, 1H), 7.8 (s, 1H); 13C NMR (CD3OD) δ 24.8, 31.7 (3C), 31.9, 32.9, 35.6, 39.5, 48.6, 125.7, 128.5, 131.6, 132.0, 140.9, 152.8, 170.3, 179.0. Anal. Calcd for C17H24O4S: C, 62.93; H, 7.46; S, 9.88. Found: C, 63.02; H, 7.36; S, 9.82.

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