65 (s, 3H, OCH3. 13C NMR ((CD3)2SO, 125 MHz): 186.7, 156.eight, 148.2, 147.1, 146.7, 146.1, 142.8, 136.7, 128.five, 123.3, 121.77, 121.75, 121.7, 119.3, 117.2, 112.0, 111.7, 111.1, 95.0, 55.7, 55.3. HPLC: 13.87 min., purity at 254 nm 93.4 . HRMS (ESI+): m/z calculated for C23H18N3O8 [M+H]+ 464.1088, identified 464.1087. four.1.22. 2-(3-Hydroxy-4-methoxyphenyl)-3-(4-nitrobenzoyl)-6-methoxyindole (26)–To a well-stirred answer of compound 14 (0.14 g, 0.27 mmol) in THF (ten mL) at 0 was added TBAF (0.40 mL, 0.40 mmol, 1 M in THF) dropwise. The reaction mixture was stirred for 30 min even though warming to room temperature. The reaction mixture was quenched with water (ten mL) and extracted with EtOAc (three 10 mL). The combined organic extract was dried more than Na2SO4 and concentrated under reduced stress. Purification by flash column chromatography employing a prepacked 50 g silica column [solvent A: EtOAc; solvent B: hexanes; gradient: 12 A / 88 B (three CV), 12 A / 88 B 100 A / 0 B (11 CV), 100 A / 0 B (two CV); flow rate: 40 mL/min; monitored at 254 and 280 nm] afforded the preferred indole phenol ligand 26 (0.02 g, 0.05 mmol, 19 , Rf 0.23 (50:50 hexanes:EtOAc)) as a yellow powder. 1H NMR ((CD3)2SO, 500 MHz): 12.04 (br s, 1H, NH), 9.05 (s, 1H, OH), 7.98 (d, J = eight.0 Hz, 2H, ArH), 7.83 (d, J = eight.5 Hz, 1H, ArH), 7.61 (d, J = eight.5 Hz, 2H, ArH), 6.95 (d, J = 1.0 Hz, 1H, ArH), six.85 (dd, J = 8.five Hz, 1.five Hz, 1H, ArH), 6.71 (s, 1H, ArH), six.68 (d, J = eight.5 Hz, 1H, ArH), six.63 (d, J = eight.5 Hz, 1H, ArH), 3.81 (s, 3H, OCH3), 3.65 (s, 3H, OCH3). 13C NMR ((CD3)2SO, 125 MHz): 190.1, 156.6, 148.3, 148.0, 146.1, 146.0, 145.6, 136.6, 129.eight, 123.9, 122.6, 122.0, 121.47, 121.45, 116.eight, 111.62, 111.55, 111.4, 94.9, 55.7, 55.3. HPLC: 13.19 min., purity at 254 nm 99 . HRMS (ESI+): m/z calculated for C23H19N2O6 [M+H]+ 419.1238, found 419.1237. four.1.23.2-(3-Hydroxy-4-methoxyphenyl)-3-(3-nitrobenzoyl)-6-methoxyindole (27)–To a well-stirred option of compound 15 (0.13 g, 0.25 mmol) in THF (10 mL) at 0 was added TBAF (0.38 mL, 0.38 mmol, 1 M in THF) dropwise.CPDA The reaction mixture was stirred for 30 min although warming to space temperature.RI-1 The reaction mixture was quenched with water (ten mL) and extracted with EtOAc (three ten mL). The combined organic extract was dried more than Na2SO4 and concentrated under reduced pressure. Purification by flash column chromatography using a prepacked 50 g silica column [solvent A: EtOAc; solvent B: hexanes; gradient: 15 A / 85 B (4.five CV), 40 A / 60 B (16 CV), 40 A / 60 B 100 A / 0 B (two CV), one hundred A / 0 B (ten.5 CV); flow price: 40 mL/min; monitored at 254 and 280 nm] afforded the desired indole phenol ligand 27 (0.ten g, 0.25 mmol, Rf = 0.28 (50:50 hexanes:EtOAc)) quantitatively as a yellow powder.PMID:24078122 1H NMR ((CD3)2CO, 500 MHz): 10.95 (br s, 1H, NH), 8.25 (t, J = 2.0 Hz, 1H, ArH), 8.13 (ddd, J = 8.0 Hz, two.0 Hz, 1.0 Hz, 1H, ArH), eight.02 (d, J = eight.5 Hz, 1H, ArH), 7.93 (dt, J = 7.5 Hz, 1.0 Hz, 1H, ArH), 7.69 (s, 1H, OH), 7.49 (t, J = 8.0 Hz, 1H, ArH), 7.06 (d, J = two.0 Hz, 1H, ArH), 6.91 (dd, J = 9.0 Hz, 2.5 Hz, 1H, ArH), 6.81 (d, J = 2.0 Hz, 1H, ArH), 6.78 (dd, J = eight.5 Hz, two.0 Hz, 1H, ArH), six.73 (d, J = eight.0 Hz, 1H, ArH), three.86 (s, 3H, OCH3), 3.75 (s, 3H, OCH3). 13C NMR ((CD3)2CO, 125 MHz): 190.5, 158.5, 149.two, 148.five, 147.4, 146.0, 143.1, 138.0, 135.9, 130.1, 125.8, 125.7, 124.8, 123.7, 123.0, 122.9, 117.five, 113.0, 112.7, 112.three, 95.8, 56.5, 56.0. HPLC: 12.97 min., purity at 254 nm 99 . HRMS (ESI+): m/z calculated for C23H19N2O6 [M+H]+ 419.1238, discovered 419.1236.NIH-PA Author Manuscript.