Tuning Benzylic C−H Functionalization of (Thio)xanthenes with Electrochemistry
Abstract
:1. Introduction
2. Results and Discussion
3. Materials and Methods
3.1. General Considerations
3.2. Typical Procedure for the Synthesis of 3a
- 1-Phenyl-2-(9H-xanthen-9-yl)ethan-1-one (3a) was prepared following general procedure [46], and the reaction mixture was purified by flash column chromatography with petroleum ether and ethylacetate (PE/EA = 100:1) to afford the product 3a (63.8 mg, 71% yield). 1H NMR (600 MHz, CDCl3) δ 7.81 (d, J = 7.2 Hz, 2H), 7.50 (t, J = 7.2 Hz, 1H), 7.37 (t, J = 7.8 Hz, 2H), 7.32 (dd, J = 7.2, 1.2 Hz, 2H), 7.23–7.19 (m, 2H), 7.12 (d, J = 8.4 Hz, 2H), 7.04–7.00 (m, 2H), 4.85 (t, J = 6.0 Hz, 1H), 3.35 (d, J = 6.6 Hz, 2H). 13C NMR (151 MHz, CDCl3) δ 197.9, 152.4, 137.0, 133.1, 128.8, 128.5, 128.1, 127.9, 125.5, 123.5, 116.6, 49.7, 34.7. HRMS (ESI) calcd. for C21H16NaO2+ ([M + Na]+): 323.1043, found: 323.1044.
- 1-(p-tolyl)-2-(9H-Xanthen-9-yl)ethan-1-one (3b) was prepared following general procedure, [47] and the reaction mixture was purified by flash column chromatography with petroleum ether and ethylacetate (PE/EA = 100:1) to afford the product 3b (59.2 mg, 63% yield). White solid; m.p.: 108~109 °C. 1H NMR (600 MHz, CDCl3) δ 7.71 (d, J = 7.8 Hz, 2H), 7.32 (dd, J = 7.8, 1.2 Hz, 2H), 7.22–7.19 (m, 2H), 7.17 (d, J = 8.4 Hz, 2H), 7.11 (dd, J = 7.8, 1.2 Hz, 2H), 7.03–7.00 (m, 2H), 4.85 (t, J = 6.6 Hz, 1H), 3.32 (d, J = 6.6 Hz, 2H), 2.36 (s, 3H). 13C NMR (151 MHz, CDCl3) δ 197.69, 152.46, 144.09, 134.68, 129.33, 128.98, 128.36, 127.95, 125.75, 123.59, 116.65, 49.77, 34.81, 21.73. HRMS (ESI) calcd. for C22H18NaO2+ ([M + Na]+): 337.1199, found: 337.1203.
- 1-(4-Pentylphenyl)-2-(9H-xanthen-9-yl)ethan-1-one (3c) was prepared following general procedure, and the reaction mixture was purified by flash column chromatography with petroleum ether and ethylacetate (PE/EA = 100:1) to afford the product 3c (82.2 mg, 75% yield). White solid; m.p.: 117~118 °C. 1H NMR (600 MHz, CDCl3) δ 7.73 (d, J = 8.4 Hz, 2H), 7.32 (dd, J = 7.8, 1.2 Hz, 2H), 7.22–7.16 (m, 2H), 7.17 (d, J = 8.4 Hz, 2H), 7.11 (d, J = 8.4 Hz, 2H), 7.03–7.00 (m, 2H), 4.85 (t, J = 6.6 Hz, 1H), 3.33 (d, J = 6.6 Hz, 2H), 2.60 (t, J = 7.8 Hz, 2H), 1.58–1.32 (m, 2H), 1.31–1.25 (m, 4H), 0.88 (t, J = 7.2 Hz, 3H). 13C NMR (151 MHz, CDCl3) δ 197.5, 152.3, 148.9, 134.7, 128.9, 128.6, 128.3, 127.8, 125.7, 123.5, 116.5, 49.7, 34.6, 31.4, 30.8, 22.5, 22.3, 14.0. HRMS (ESI) calcd. for C26H26NaO2+ ([M + Na]+): 393.1825, found: 393.1826.
- 1-(4′-Ethyl-[1,1′-biphenyl]-4-yl)-2-(9H-xanthen-9-yl)ethan-1-one (3d) was prepared following general procedure, and the reaction mixture was purified by flash column chromatography with petroleum ether and ethylacetate (PE/EA = 100:1) to afford the product 3d (78.6 mg, 65% yield). White solid; m.p.: 122~123 °C. 1H NMR (600 MHz, CDCl3) δ 7.86 (d, J = 8.4 Hz, 2H), 7.59 (d, J = 8.4 Hz, 2H), 7.51 (d, J = 7.8 Hz, 2H), 7.34 (dd, J = 7.8, 1.8 Hz, 2H), 7.29 (d, J = 8.4 Hz, 2H), 7.23–7.20 (m, 2H), 7.13 (dd, J = 7.8, 0.6 Hz, 2H), 7.03 (td, J = 7.2, 1.2 Hz, 2H), 4.88 (t, J = 6.6 Hz, 1H), 3.38 (d, J = 6.6 Hz, 2H), 2.70 (q, J = 7.8 Hz, 2H), 1.28 (s, 3H). 13C NMR (151 MHz, CDCl3) δ 197.6, 152.5, 145.9, 144.8, 137.2, 135.6, 129.0, 128.8, 128.6, 128.0, 127.3, 127.0, 125.7, 123.6, 116.7, 49.9, 34.9, 28.7, 15.7. HRMS (ESI) calcd. for C29H24NaO2+ ([M + Na]+): 427.1669, found: 427.1668.
- 1-(o-tolyl)-2-(9H-Xanthen-9-yl)ethan-1-one (3e) was prepared following general procedure, and the reaction mixture was purified by flash column chromatography with petroleum ether and ethylacetate (PE/EA = 100:1) to afford the product 3e (49.8 mg, 53% yield). White solid; m.p.: 105~106 °C. 1H NMR (600 MHz, CDCl3) δ 7.33 (d, J = 7.2 Hz, 2H), 7.30–7.27 (m, 2H), 7.21 (t, J = 7.8 Hz, 2H), 7.18 (d, J = 7.2 Hz, 1H), 7.12–7.09 (m, 3H), 7.04 (t, J = 7.2 Hz, 2H), 4.84 (t, J = 6.6 Hz, 1H), 3.26 (d, J = 6.6 Hz, 2H), 2.43 (s, 3H). 13C NMR (151 MHz, CDCl3) δ 202.1, 152.5, 138.2, 132.0, 131.4, 128.9, 128.6, 128.0, 125.7, 125.7, 123.6, 116.7, 52.7, 35.0, 21.2. HRMS (ESI) calcd. for C22H18NaO2+ ([M + Na]+): 337.1199, found: 337.1201.
- 1-(m-tolyl)-2-(9H-Xanthen-9-yl)ethan-1-one (3f) was prepared following general procedure, and the reaction mixture was purified by flash column chromatography with petroleum ether and ethylacetate (PE/EA = 100:1) to afford the product 3f (60.0 mg, 68% yield). White solid; m.p.: 111~112 °C. 1H NMR (600 MHz, CDCl3) δ 7.54–7.50 (m, 2H), 7.24 (t, J = 7.2 Hz, 2H), 7.20–7.16 (m, 2H), 7.13 (t, J = 7.8 Hz, 2H), 7.04 (d, J = 7.8 Hz, 2H), 6.95 (t, J = 7.2 Hz, 2H), 4.77 (t, J = 6.6 Hz, 1H), 3.26 (d, J = 6.6 Hz, 2H), 2.26 (s, 3H). 13C NMR (151 MHz, CDCl3) 198.3, 152.6, 138. 6, 137.2, 134.1, 129.1, 128.9, 128.6, 128.1, 125.8, 125.5, 123.7, 116.8, 50.0, 34.9, 21.5.
- 1-(Naphthalen-1-yl)-2-(9H-xanthen-9-yl)ethan-1-one (3g) was prepared following general procedure, and the reaction mixture was purified by flash column chromatography with petroleum ether and ethylacetate (PE/EA = 100:1) to afford the product 3g (64.2 mg, 61% yield). White solid; m.p.: 116~117 °C. 1H NMR (600 MHz, CDCl3) δ 8.50 (d, J = 8.4 Hz, 1H), 7.91 (d, J = 7.8 Hz, 1H), 7.84 (d, J = 7.8 Hz, 1H), 7.59–7.55 (m, 1H), 7.59–7.50 (m, 1H), 7.48 (dd, J = 7.2, 1.1 Hz, 1H), 7.38 (dd, J = 7.2, 1.2 Hz, 2H), 7.36–7.32 (m, 1H), 7.24–7.21 (m, 2H), 7.12 (dd, J = 8.4, 1.2 Hz, 2H), 7.06–7.03 (m, 2H), 4.94 (t, J = 6.6 Hz, 1H), 3.42 (d, J = 6.6 Hz, 2H). 13C NMR (151 MHz, CDCl3) δ 202.2, 152.5, 136.1, 134.0, 132.9, 130.2, 128.9, 128.6, 128.1, 127.9, 126.6, 125.8, 125.5, 124.4, 123.7, 53.2, 35.5. HRMS (ESI) calcd. for C25H18NaO2+ ([M+Na]+): 373.1199, found: 373.1200.
- 2-(2-Methyl-9H-xanthen-9-yl)-1-phenylethan-1-one (3h) was prepared following general procedure, and the reaction mixture was purified by flash column chromatography with petroleum ether and ethylacetate (PE/EA = 100:1) to afford the product 3h (65.8 mg, 70% yield). White solid; m.p.: 102~103 °C. 1H NMR (600 MHz, CDCl3) δ 7.81 (d, J = 7.8 Hz, 2H), 7.50 (t, J = 7.2 Hz, 1H), 7.37 (t, J = 7.2 Hz, 2H), 7.31 (d, J = 7.8 Hz, 1H), 7.19 (t, J = 7.2 Hz, 1H), 7.10 (d, J = 7.8 Hz, 2H), 7.02–6.89 (m, 3H), 4.80 (t, J = 6.6 Hz, 1H), 3.35 (d, J = 6.6 Hz, 2H), 2.27 (s, 3H). 13C NMR (151 MHz, CDCl3) δ 198.2, 152.6, 150.3, 137.2, 133.21, 133.0, 129.2, 129.0, 128.6, 128.6, 128.2, 127.9, 125.7, 125.3, 123.4, 116.6, 116.4, 49.9, 34.8, 20.8.
- 2-(4-Methyl-9H-xanthen-9-yl)-1-phenylethan-1-one (3i) was prepared following general procedure, and the reaction mixture was purified by flash column chromatography with petroleum ether and ethylacetate (PE/EA = 100:1) to afford the product 3i (67.8 mg, 72% yield). White solid; m.p.: 107~108 °C. 1H NMR (600 MHz, CDCl3) δ 7.71 (d, J = 8.4 Hz, 2H), 7.33 (d, J = 7.8 Hz, 2H), 7.23 –7.20 (m, 2H), 7.17 (d, J = 8.4 Hz, 2H), 7.12 (d, J = 8.4 Hz, 2H), 7.02 (t, J = 7.8 Hz, 2H), 4.86 (t, J = 6.6 Hz, 1H), 3.33 (d, J = 6.6 Hz, 2H), 2.36 (s, 3H). 13C NMR (151 MHz, CDCl3) δ 197.5, 152.3, 143.9, 134.5, 130.0, 129.8, 129.5, 129.5, 129.2, 128.8, 128.3, 128.2, 127.8, 127.3, 125.6, 123.4, 116.5, 49.6, 34.7, 21.6. HRMS (ESI) calcd. for C22H18NaO2+ ([M + Na]+): 337.1199, found: 337.1196.
- 2-(4-(tert-Butyl)-9H-xanthen-9-yl)-1-phenylethan-1-one (3j) was prepared following general procedure, and the reaction mixture was purified by flash column chromatography with petroleum ether and ethylacetate (PE/EA = 100:1) to afford the product 3j (74.0 mg, 70% yield). White solid; m.p.: 113~114 °C. 1H NMR (600 MHz, CDCl3) δ 7.78–7.75 (m, 2H), 7.41–7.38 (m, 2H), 7.32 (dd, J = 7.8, 1.2 Hz, 2H), 7.22–7.19 (m, 2H), 7.12 (dd, J = 8.4, 1.2 Hz, 2H), 7.02 (td, J = 7.2, 1.2 Hz, 2H), 4.87 (t, J = 6.6 Hz, 1H), 3.34 (d, J = 6.6 Hz, 2H), 1.30 (s, 9H). 13C NMR (151 MHz, CDCl3) δ 196.4, 155.9, 151.3, 133.4, 128.8, 128.7, 127.8, 127.3, 127.0, 126.8, 126.3, 124.7, 124.6, 124.4, 122.4, 121.8, 115.5, 48.7, 34.0, 33.5, 29.9. HRMS (ESI) calcd. for C25H24NaO2+ ([M + Na]+): 379.1669, found: 379.1670.
3.3. Typical Procedure for the Synthesis of 4a
- N-(9H-xanthen-9-yl)acetamide (4a) was prepared following general procedure, and the reaction mixture was purified by flash column chromatography with petroleum ether and ethylacetate (PE/EA = 5:1) to afford the product 4a (48.7 mg, 68% yield). White solid; m.p.: 238~239 °C. 1H NMR (600 MHz, CDCl3) δ 7.48–7.46 (m, 2H), 7.32–7.28 (m, 2H), 7.13–7.10 (m, 4H), 6.49 (d, J = 9.0 Hz, 1H), 6.05 (br, d, J = 9.0 Hz, 1H), 2.00 (s, 3H). 13C NMR (151 MHz, CDCl3) δ 169.2, 151.3, 129.8, 129.4, 123.7, 121.3, 116.8, 44.0, 23.5. HRMS (ESI) calcd. for C15H13NNaO2+ ([M + Na]+): 262.0838, found: 262.0839.
- N-(2-Methyl-9H-xanthen-9-yl)acetamide (4b) was prepared following general procedure, and the reaction mixture was purified by flash column chromatography with petroleum ether and ethylacetate (PE/EA = 5:1) to afford the product 4b (49.5 mg, 65% yield). White solid; m.p.: 242~243 °C. 1H NMR (600 MHz, CDCl3) δ 7.46 (d, J = 7.8 Hz, 1H), 7.31–7.27 (m, 1H), 7.11–7.08 (m, 3H), 7.00 (d, J = 8.4 Hz, 1H), 6.46 (d, J = 9.0 Hz, 1H), 6.00 (br, d, J = 9.0 Hz, 1H), 2.32 (s, 3H), 2.01 (s, 3H). 13C NMR (151 MHz, CDCl3) δ 169.2, 151.4, 149.2, 133.2, 130.2, 129.8, 129.8, 129.3, 123.5, 121.3, 120.8, 116.7, 116.5, 44.1, 23.6, 20.8. HRMS (ESI) calcd. for C16H15NNaO3+ ([M + Na]+): 276.0095, found: 276.0092.
- N-(2-Methoxy-9H-xanthen-9-yl)acetamide (4c) was prepared following general procedure, and the reaction mixture was purified by flash column chromatography with petroleum ether and ethylacetate (PE/EA = 5:1) to afford the product 4c (60.3 mg, 75% yield). White solid; m.p.: 251~252 °C. 1H NMR (600 MHz, CDCl3) δ 7.46 (d, J = 7.2 Hz, 1H), 7.31–7.27 (m, 1H), 7.11–7.07 (m, 2H), 7.04 (d, J = 9.0 Hz, 1H), 6.98 (d, J = 3.0 Hz, 1H), 6.87 (dd, J = 9.0, 3.0 Hz, 1H), 6.47 (d, J = 9.0 Hz, 1H), 6.01 (br, d, J = 9.0 Hz, 1H), 3.79 (s, 3H), 2.01 (s, 3H). 13C NMR (151 MHz, CDCl3) δ 169.2, 155.7, 151.5, 145.4, 129.8, 129.4, 123.5, 121.7, 120.7, 117.7, 116.7, 116.4, 112.8, 55.9, 44.5, 23.6. HRMS (ESI) calcd. for C16H15NNaO3+ ([M + Na]+): 292.0944, found 292.0947.
- N-(2-Phenyl-9H-xanthen-9-yl)acetamide (4d) was prepared following general procedure, and the reaction mixture was purified by flash column chromatography with petroleum ether and ethylacetate (PE/EA = 5:1) to afford the product 4d (57.7 mg, 61% yield). White solid; m.p.: 247~248 °C. 1H NMR (600 MHz, CDCl3) δ 7.70 (d, J = 1.8 Hz, 1H), 7.58–7.56 (m, 2H), 7.54 (dd, J = 9.0, 2.4 Hz, 1H), 7.51–7.49 (m, 1H), 7.43 (t, J = 7.2 Hz, 2H), 7.36–7.30 (m, 2H), 7.18 (d, J = 8.4 Hz, 1H), 7.14–7.11 (m, 2H), 6.57 (d, J = 9.6 Hz, 1H), 6.06 (br, J = 9.6 Hz, 1H), 2.01 (s, 3H). 13C NMR (151 MHz, CDCl3) δ 169.2, 151.2, 150.8, 140.2, 136.9, 129.9, 129.5, 129.0, 128.2, 128.2, 127.4, 127.0, 123.8, 121.5, 121.2, 117.2, 116.8, 44.1, 23.6. HRMS (ESI) calcd. for C21H17NNaO2+ ([M + Na]+): 338.1151, found: 338.1147.
- N-(2-(Trifluoromethyl)-9H-xanthen-9-yl)acetamide (4e) was prepared following general procedure, and the reaction mixture was purified by flash column chromatography with petroleum ether and ethylacetate (PE/EA = 5:1) to afford the product 4e (51.6 mg, 56% yield). White solid; m.p.: 244~245 °C. 1H NMR (600 MHz, CDCl3) δ 7.75 (s, 1H), 7.55 (dd, J = 8.4, 1.2 Hz, 1H), 7.45 (d, J = 8.4 Hz, 1H), 7.35–7.31 (m, 1H), 7.20 (d, J = 8.4 Hz, 1H), 7.15 (t, J = 7.8 Hz, 1H), 7.13 (d, J = 8.4 Hz, 1H), 6.52 (d, J = 9.0 Hz, 1H), 6.10 (br, s, 1H), 2.04 (s, 3H). 13C NMR (151 MHz, CDCl3) δ 169.4, 153.5, 150.7, 129.8, 129.64, 127.4 (q, J = 3.6), 126.5 (q, J = 3.2), 125.9 (q, J = 271.5), 124.5, 123.1, 121.8, 121.3, 120.7, 117.4, 116.9, 43.7, 23.5. 19F NMR (565 MHz, CDCl3) δ − 77.30. HRMS (ESI) calcd. for C16H12F3NNaO2+ ([M + Na]+): 330.0172, found: 330.0175.
- N-(4-Methyl-9H-xanthen-9-yl)acetamide (4f) was prepared following general procedure, and the reaction mixture was purified by flash column chromatography with petroleum ether and ethylacetate (PE/EA = 5:1) to afford the product 4f (52.5 mg, 69% yield). White solid; m.p.: 239~240 °C. 1H NMR (600 MHz, CDCl3) 7.50 (d, J = 7.2 Hz, 1H), 7.31 (t, J = 8.4 Hz, 2H), 7.16 (d, J = 8.4 Hz, 2H), 7.13–7.10 (m, 1H), 7.02 (t, J = 7.8 Hz, 1H), 6.50 (d, J = 9.0 Hz, 1H), 5.92 (br, d, J = 8.4 Hz, 1H), 2.40 (s, 3H), 2.00 (s, 3H). 13C NMR (151 MHz, CDCl3) δ 169.0, 151.2, 151.0, 139.6, 129.7, 129.4, 129.2, 124.6, 123.5, 121.3, 118.1, 116.9, 116.6, 43.8, 23.4, 21.2. HRMS (ESI) calcd. for C16H15NNaO2+ ([M + Na]+): 276.0995, found: 276.0997.
- N-(4-Phenyl-9H-xanthen-9-yl)acetamide (4g) was prepared following general procedure, and the reaction mixture was purified by flash column chromatography with petroleum ether and ethylacetate (PE/EA = 5:1) to afford the product 4g (54.7 mg, 58% yield). White solid; m.p.: 251~152 °C. 1H NMR (600 MHz, CDCl3) δ 7.60 (d, J = 7.0 Hz, 2H), 7.51–7.46 (m, 4H), 7.42–7.38 (m, 1H), 7.36 (dd, J = 7.8, 1.6 Hz, 1H), 7.29–7.26 (m, 1H), 7.19 (t, J = 7.8 Hz, 1H), 7.12 (td, J = 7.8, 1.2 Hz, 1H), 7.03 (d, J = 8.4 Hz, 1H), 6.56 (d, J = 9.0 Hz, 1H), 6.06 (br, J = 8.4 Hz, 1H), 2.02 (s, 3H). 13C NMR (151 MHz, CDCl3) δ 169.2, 151.3, 148.3, 137.5, 130.8, 130.2, 129.8, 129.6, 129.3, 129.1, 128.3, 127.5, 123.9, 123.7, 122.0, 121.3, 116.9, 44.5, 23.6. HRMS (ESI) calcd. for C21H17NNaO2+ ([M + Na]+): 338.1151, found: 338.1151.
- N-(2,3-Dimethyl-9,10-dihydroanthracen-9-yl)acetamide (4h) was prepared following general procedure, and the reaction mixture was purified by flash column chromatography with petroleum ether and ethylacetate (PE/EA = 5:1) to afford the product 4h (57.2 mg, 72% yield). White solid; m.p.: 247~248 °C. 1H NMR (600 MHz, CDCl3) δ 7.66 (dd, J = 7.8, 0.6 Hz, 1H), 7.30–7.27 (m, 1H), 7.12 (d, J = 8.4 Hz, 1H), 7.10–7.07 (m, 2H), 6.92 (d, J = 8.4 Hz, 1H), 6.55 (d, J = 9.0 Hz, 1H), 5.85 (br, d, J = 7.8 Hz, 1H), 2.27 (s, 3H), 2.26 (s, 3H), 1.91 (s, 3H). 13C NMR (151 MHz, CDCl3) δ 168.4, 151.1, 150.8, 136.8, 131.9, 130.7, 130.2, 129.2, 123.6, 122.8, 119.0, 116.3, 114.1, 42.9, 23.3, 20.2, 15.2. HRMS (ESI) calcd. for C17H17NNaO2+ ([M + Na]+): 290.1151, found: 290.1152.
- N-(1,3-Dimethyl-9,10-dihydroanthracen-9-yl)acetamide (4i) was prepared following general procedure, and the reaction mixture was purified by flash column chromatography with petroleum ether and ethylacetate (PE/EA = 5:1) to afford the product 4i (51.6 mg, 67% yield). White solid; m.p.: 244~245 °C. 1H NMR (600 MHz, CDCl3) δ 7.66–7.63 (m, 1H), 7.29 (td, J = 7.8, 1.8 Hz, 1H), 7.11–7.08 (m, 2H), 6.82 (d, J = 4.8 Hz, 2H), 6.47 (d, J = 9.6 Hz, 1H), 5.78 (br, d, J = 9.0 Hz, 1H), 2.34 (s, 3H), 2.32 (s, 3H), 1.91 (s, 3H). 13C NMR (151 MHz, CDCl3) δ 168.4, 152.4, 151.3, 139.4, 138.6, 130.2, 129.2, 126.4, 123.7, 122.9, 116.5, 116.2, 115.1, 42.4, 23.4, 21.2, 18.7. HRMS (ESI) calcd. for C17H17NNaO2+ ([M + Na]+): 290.1151, found: 290.1155.
- N-(1,2,3,10-Tetrahydrocyclopenta[b]xanthen-10-yl)acetamide (4j) was prepared following general procedure, and the reaction mixture was purified by flash column chromatography with petroleum ether and ethylacetate (PE/EA = 5:1) to afford the product 4j (51.9 mg, 70% yield). White solid; m.p.: 236~237 °C. 1H NMR (600 MHz, CDCl3) δ 7.58 (dd, J = 8.4, 1.8 Hz, 1H), 7.30–7.27 (m, 1H), 7.18 (d, J = 8.4 Hz, 1H), 7.11–7.07 (m, 2H), 6.94 (d, J = 8.4 Hz, 1H), 6.48 (d, J = 9.6 Hz, 1H), 5.81 (br, d, J = 9.6 Hz, 1H), 2.99–2.94 (m, 1H), 2.90 (t, J = 8.4 Hz, 2H), 2.87–2.81 (m, 1H), 2.17–2.08 (m, 2H), 1.96 (s, 3H). 13C NMR (151 MHz, CDCl3) δ 168.5, 151.327, 150.6, 144.8, 139.4, 130.2, 129.3, 125.1, 123.6, 122.2, 116.6, 116.4, 114.9, 42.8, 32.5, 31.4, 25.7, 23.4. HRMS (ESI) calcd. for C18H17NNaO2+ ([M + Na]+): 302.1151, found 302.1154.
- N-(10-Methoxy-12H-benzo[a]xanthen-12-yl)acetamide (4k) was prepared following general procedure, and the reaction mixture was purified by flash column chromatography with petroleum ether and ethylacetate (PE/EA = 3:1) to afford the product 4k (61.3 mg, 64% yield). White solid; m.p.: 258~259 °C. 1H NMR (600 MHz, CDCl3) δ 8.07 (d, J = 8.4 Hz, 1H), 7.84 (d, J = 6.6 Hz, 1H), 7.82 (d, J = 8.4 Hz, 1H), 7.60 (t, J = 6.6 Hz, 1H), 7.46 (t, J = 7.2 Hz, 1H), 7.30 (d, J = 9.0 Hz, 1H), 7.25 (d, J = 3.0 Hz, 1H), 7.13 (d, J = 9.0 Hz, 1H), 7.08 (d, J = 9.4 Hz, 1H), 6.92 (dd, J = 8.4, 3.0 Hz, 1H), 5.85 (br, d, J = 9.6 Hz, 1H), 3.83 (s, 3H), 1.92 (s, 3H). 13C NMR (151 MHz, CDCl3) δ 168.7, 156.2, 150.3, 144.8, 131.8, 130. 5, 130.4, 128.7, 127.8, 124.8, 123.0, 122.5, 118.0, 117.6, 116.8, 112.6, 111.5, 56.0, 42.2, 23.4. HRMS (ESI) calcd. for C20H17NNaO2+ ([M + Na]+): 342.1101, found 342.1102.
- N-(7H-benzo[c]xanthen-7-yl)acetamide (4l) was prepared following general procedure, and the reaction mixture was purified by flash column chromatography with petroleum ether and ethylacetate (PE/EA = 5:1) to afford the product 4l (47.6 mg, 55% yield). White solid; m.p.: 250~251 °C. 1H NMR (600 MHz, CDCl3)δ 8.43 (d, J = 8.4 Hz, 1H), 7.83 (d, J = 7.2 Hz, 1H), 7.60 –7.54 (m, 4H), 7.51–7.48 (m, 1H), 7.38–7.35 (m, 1H), 7.30 (dd, J = 8.4, 1.2 Hz, 1H), 7.19–7.16 (m, 1H), 6.66 (d, J = 9.0 Hz, 1H), 6.04 (br, d, J = 9.0 Hz, 1H), 2.02 (s, 3H). 13C NMR (151 MHz, CDCl3) δ 169.1, 151.0, 146.3, 134.0, 129.9, 129.3, 127.6, 127.0, 126.3, 126.3, 124.0, 123.9, 123.3, 121.8, 121.2, 116.8, 114.8, 44.2, 23.5. HRMS (ESI) calcd. for C19H15
- N-(12H-benzo[a]xanthen-12-yl)acetamide (4m) was prepared following general procedure, and the reaction mixture was purified by flash column chromatography with petroleum ether and ethylacetate (PE/EA = 5:1) to afford the product 4m (50.3 mg, 58% yield). White solid; m.p.: 249~250 °C. 1H NMR (600 MHz, CDCl3) δ 8.43 (d, J = 8.4 Hz, 1H), 7.83 (d, J = 7.8 Hz, 1H), 7.60–7.54 (m, 4H), 7.50 (d, J = 8.4 Hz, 1H), 7.37 (t, J = 7.8 Hz, 1H), 7.30 (d, J = 7.8 Hz, 1H), 7.17 (t, J = 7.2 Hz, 1H), 6.67 (d, J = 9.6 Hz, 1H), 6.01 (br, J = 9.0 Hz, 1H), 2.02 (s, 3H). 13C NMR (151 MHz, CDCl3) δ 169.1, 151.1, 146.4, 134.1, 130.0, 129.4, 127.8, 127.1, 126.4, 126.4, 124.1, 123.4, 121.9, 121.4, 116.9, 114.9, 44.4, 23.6. HRMS (ESI) calcd. for C19H15NNaO2+ ([M + Na]+): 312.0095, found 312.0098.
- N-(9H-xanthen-9-yl)butyramide (4n) was prepared following general procedure, and the reaction mixture was purified by flash column chromatography with petroleum ether and ethylacetate (PE/EA = 9:1) to afford the product 4n (40.1 mg, 50% yield). White solid; m.p.: 262~263 °C. 1H NMR (600 MHz, CDCl3) δ 7.45 (d, J = 7.8 Hz, 2H), 7.30 (t, J = 7.2 Hz, 2H), 7.12–7.09 (m, 4H), 6.52 (d, J = 9.0 Hz, 1H), 6.05 (br, d, J = 8.4 Hz, 1H), 2.17 (t, J = 7.8 Hz, 2H), 1.72–1.67 (m, 2H), 0.94 (t, J = 7.2 Hz, 3H). 13C NMR (151 MHz, CDCl3) δ 172.2, 151.2, 129.8, 129.4, 123.7, 121.4, 116.8, 43.8, 38.9, 19.3, 13.9. HRMS (ESI) calcd. for C18H19NO2+ ([M + H]+): 267.1379, found: 267.1377.
- N-(9H-thioxanthen-9-yl)acetamide (4o) was prepared following general procedure, and the reaction mixture was purified by flash column chromatography with petroleum ether and ethylacetate (PE/EA = 5:1) to afford the product 4o (48.9 mg, 64% yield). White solid; m.p.: 237~238 °C. 1H NMR (600 MHz, CDCl3) δ 7.58 (dd, J = 6.0, 2.4 Hz, 2H), 7.47–7.45 (m, 2H), 7.28–7.25 (m, 4H), 6.30 (d, J = 9.0 Hz, 1H), 6.23 (br, d, J = 7.2 Hz, 1H), 1.88 (s, 3H). 13C NMR (151 MHz, CDCl3) δ 169.0, 134.9, 133.0, 129.6, 128.0, 127.2, 127.2, 53.4, 23.5. HRMS (ESI) calcd. for C15H13NNaOS+ ([M + Na]+): 278.0610, found: 278.0613.
4. Conclusions
Supplementary Materials
Author Contributions
Funding
Institutional Review Board Statement
Informed Consent Statement
Data Availability Statement
Conflicts of Interest
Sample Availability
References
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Entry | Electrode | Temp (°C) | Yield (%) | |
---|---|---|---|---|
3a | 4a | |||
1 | C(+)|Pt(−) | rt | 32 | 40 |
2 | C(+)|Pt(−) | 30 | 38 | 37 |
3 | C(+)|Pt(−) | 40 | 45 | 21 |
4 | C(+)|Pt(−) | 50 | 71 | 6 |
5 | C(+)|Pt(−) | 60 | 65 | trace |
6 | C(+)|Pt(−) | 70 | 52 | trace |
7 | C(+)|Ni(−) | 50 | 14 | 25 |
8 | Pt(+)|C(−) | 50 | 46 | 17 |
9 | GF(+)|GF(−) | 50 | n.d. | 43 |
10 c | C(+)|Pt(−) | 50 | 55 | 8 |
11 d | C(+)|Pt(−) | 50 | 37 | 10 |
12 e | C(+)|Pt(−) | 50 | 48 | trace |
13 f | C(+)|Pt(−) | 50 | 22 | trace |
14 | GF(+)|GF(−) | rt | n.d. | 35 |
15 f | GF(+)|GF(−) | rt | n.d. | 50 |
16 f,g | GF(+)|GF(−) | rt | n.d. | 77 |
17 c,f,g | GF(+)|GF(−) | rt | n.d. | 61 |
18 d,f,g | GF(+)|GF(−) | rt | n.d. | 33 |
19 e,f,g | GF(+)|GF(−) | rt | n.d. | 58 |
20 h | GF(+)|GF(−) | rt | n.d. | n.d. |
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Wang, C.; Yang, N.; Li, C.; He, J.; Li, H. Tuning Benzylic C−H Functionalization of (Thio)xanthenes with Electrochemistry. Molecules 2023, 28, 6139. https://doi.org/10.3390/molecules28166139
Wang C, Yang N, Li C, He J, Li H. Tuning Benzylic C−H Functionalization of (Thio)xanthenes with Electrochemistry. Molecules. 2023; 28(16):6139. https://doi.org/10.3390/molecules28166139
Chicago/Turabian StyleWang, Changji, Na Yang, Chao Li, Jian He, and Hongji Li. 2023. "Tuning Benzylic C−H Functionalization of (Thio)xanthenes with Electrochemistry" Molecules 28, no. 16: 6139. https://doi.org/10.3390/molecules28166139