| 1.90 g |
With di-μ-chlorobis[(1,2,5,6-η)-1,5-cyclooctadiene]diiridium; 4,4′-di-tert-butyl-2,2′-bipyridine In tetrahydrofuran at 20 - 80℃; for 21h; Inert atmosphere; |
2-Methoxy-6-(4-tolylsulfinyl)phenyl Triflate (2a); Typical Procedure
To a mixture of 2-methoxyphenol (1a; 1.24 mL, 11.3 mmol), [Ir(cod)Cl]2 (35.6 mg, 52.0 μmol), and 1,3,5-trimethoxybnzene (75.6 mg, 0.447 mmol) in benzene (5.0 mL) was slowly added Et2SiH2 (1.94 mL, 10.3 mmol) at rt. The mixture was stirred for 20 min and then concentrated under reduced pressure. To the resulting oil were added B2pin2 (2.54 g, 10.0 mmol), dtbpy (26.8 mg, 0.205 mmol), [Ir(cod)Cl]2 (47.2 mg, 69.0 μmol), and HBpin (72.0 μL, 49.6 μmol) in THF (5.0 mL) at rt. After stirring for 21 h at 80 °C, aq 1 M HCl (5 mL) was slowly added to the mixture at 0 °C. The mixture was extracted with EtOAc (3 × 10 mL) and the combined organic extracts were washed with brine (10 mL) and dried (Na2SO4). After filtration, the filtrate was concentrated under reduced pressure. The residue was purified by column chromatography (silica gel 30 g, n-hexane/EtOAc 5:1) to give 2- methoxy-6-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenol (1.90 g, <7.60 mmol, <74%) as a colorless solid. A solution of the above crude 2-methoxy-6-(4,4,5,5-tetramethyl- 1,3,2-dioxaborolan-2-yl)phenol (1.00 g, <4.00 mmol) and S-(4-tolyl) 4-toluenethiosulfonate (6a; 536 mg, 1.93 mmol) dissolved in methanol (25.0 mL) were added to a mixture of CuSO4 (15.9 mg, 99.3 μmol) and K2CO3 (552 mg, 4.00 mmol) at 50 °C. After stirring for 12 h at the same temperature, the mixture was passed through a short pad of silica gel washing with EtOAc. The filtrate was concentrated under reduced pressure. The residue was purified by column chromatography (silica gel 20 g, n-hexane/EtOAc 5:1) to give 6-methoxy-2-(4-tolylthio) phenol as a colorless oil. To a solution of the resulting oil (<1.93 mmol) and i-Pr2NEt (1.31 mL, 7.50 mmol) dissolved in CH2Cl2 (25.0 mL) was slowly added trifluoromethanesulfonic anhydride (1.23 mL, 7.50 mmol) at -78 °C. After stirring for 5 min at the same temperature, sat. aq NaHCO3 (20 mL) was slowly added to the mixture . The mixture was extracted with CH2Cl2 (3 × 20 mL) and the combined organic extracts were washed with brine (10 mL) and dried (Na2SO4). After filtration, the filtrate was concentrated under reduced pressure. The residue was purified by flash column chromatography (silica gel 80 g, n-hexane/EtOAc 5:1) to give 6-methoxy-2-(4-tolylthio)phenyl triflate [443 mg, 1.18 mmol, 61% in 2 steps from S-(4-tolyl) 4-toluenethiosulfonate] as a colorless oil. To a mixture of 6-methoxy-2-(4-tolylthio)phenyl triflate (439 mg, 1.16 mmol) in CH2Cl2 (5.0 mL) was slowly added mCPBA (ca. 65%, 308 mg, ca. 1.16 mmol) at 0 °C. After gradually warming to rt, the mixture was stirred for 5 min, and to this were added sat. aq Na2S2O3 (10 mL) and sat. aq K2CO3 (10 mL). The mixture was extracted with CH2Cl2 (3 × 10 mL) and the combined organic extract were washed with brine (10 mL) and dried (Na2SO4). After filtration, the filtrate was concentrated under reduced pressure. The residue was purified by column chromatography (silica gel 20 g, n-hexane/EtOAc 5:1) to give 6-methoxy-2- (4-tolylsulfinyl)phenyl triflate (2a; 374 mg, 0.95 mmol, 82%; 19% from 2-methoxyphenol in 4 steps) as a colorless solid; mp 89-90 °C; Rf = 0.22 (n-hexane/EtOAc 5:1). 1H NMR (CDCl3, 500 MHz): δ = 2.36 (s, 3 H), 3.90 (s, 3 H), 7.10 (dd, J = 8.2, 1.5 Hz, 1 H), 7.23-7.28 (AA′BB′, 2 H), 7.50 (dd, J = 8.2, 8.2 Hz, 1 H), 7.54-7.58 (AA′BB′, 2 H), 7.60 (dd, J = 8.2, 1.5 Hz, 1 H). 13C NMR (CDCl3, 126 MHz): δ = 21.4, 56.4, 115.4, 116.3, 118.6 (q, J = 322 Hz), 125.2, 129.7, 130.2, 134.1, 140.86, 140.91, 142.4, 151.3. 19F NMR (CDCl3, 376 MHz): δ = -72.6 (s). IR (KBr): 621, 748, 876, 1086, 1132, 1206, 1212, 1423, 1475 cm-1. HRMS (ESI): m/z ([M + Na]+) calcd for C15H13F3O5S2Na+: 417.0054; found: 417.0056. |
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