反应详情

To a solution of 4.5 g (80 mmol) of potassium hydroxide in water (200 mL) and tetrahydrofuran (200 mL) was added 21.46 g (70 mmol) of methyl (2R)-2-(3,5-di-t-butyl-4-hydroxyphenyl)thiopropanoate (31). The reaction mixture was allowed to stir overnight at room temperature. The reaction solution was acidified to pH 1.2 with concentrated hydrochloric acid and and extracted with t-butyl methyl ether (3×100 mL). The combined extracts were washed with an aqueous saturated sodium chloride solution (1×300 mL) and dried (MgSO4). Filtration, concentration and recrystallization from hexane and ethyl acetate afforded 18.35 g (90%) of (2R)-2-(3,5-di-t-butyl-4-hydroxyphenyl)thiopropanoic acid (32) as a white crystalline material: m.p. 111°-112° C.; 1H NMR (CDCl3) δ1.33-1.46 (m, 21 H), 3.58-3.65 (q, J=7.1 Hz, 1 H), 5.34 (s, --OH, 1 H), 7.33 (s, 2 H), 9.12 (b, --CO2H, 1 H); 13C NMR (CDCl3) δ178.8, 154.8, 136.7, 131.8, 121.6, 46.0, 34.4, 30.2, 17.1; IR (KBr) 3608 (s), 3570 (s), 2960 (vs), 1692 (vs), 1424 (vs), 1287 (s), 1239 (vs), 1121 (vs), 884 (s), 774 (w) cm-1.

1. extractionextracted with t-butyl methyl ether (3×100 mL)
2. washThe combined extracts were washed with an aqueous saturated sodium chloride solution (1×300 mL)
3. dry with materialdried (MgSO4)
4. filtrationFiltration, concentration and recrystallization from hexane and ethyl acetate