2-Amino-3-chloro-1,4-naphthoquinone, 2-amino-3-bromo-1,4-naphthoquinone or 2-amino-3-methoxy-1,4-naphthoquinone was dissolved in freshly distilled THF (15 mL). NaH was added and the mixture was stirred at room temperature for 15 min. The appropriate acid chloride was added, drop wise, and the mixture was stirred for 24 hours under argon (mole ratio of substrate:NaH:acid chloride = 1:2.3:2.3). THF was evaporated under vacuum and the mixture was washed with ice-water (10 g ice and 10 mL water). The ice-water mixture was extracted with CH2Cl2 (30 mL, 20 mL consecutively). The combined organic phase was washed with water (3 × 20 mL), saturated NaCl solution (3 × 20 mL), and then dried over anhydrous MgSO4. The crude material was purified via triturating in hot ethanol, recrystallization in ethyl acetate and/or via column chromatography.
Characterization Data for Each Isolated Imido-Substituted Compounds 3a–u
2-Dibenzoylamino-3-chloro-1,4-naphthoquinone (3a). Yellow solid. (61%). Mp: 294–297 °C. IR (cm−1) 3328, 1698, 1672, 1618, 1590, 1573. 1H-NMR (DMSO-d6) 7.35–7.39 (t, 4H, J = 7.5 Hz), 7.46–7.50 (tt, 2H, J = 1.2, 7.5 Hz), 7.65–7.67 (m, 4H), 7.83–7.90 (m, 2H), 7.94–7.96 (dd, 1H, J = 1.7, 7.4 Hz), 8.04–8.06 (dd, 1H, J = 1.3, 8.2 Hz). 13C-NMR (CDCl3) 127.61, 127.64, 128.59, 129.11, 130.69, 131.37, 132.90, 134.45, 134.68, 134.73, 142.32, 144.33, 171.59, 177.29, 178.59. ESI HRMS m/z 438.0513 ([M+Na]+ calcd 438.0509).
2-Dibenzoylamino-3-bromo-1,4-naphthoquinone (3b). Yellow solid. (53%). Mp: 234–238 °C. IR (cm−1) 3087, 1693, 1671, 1588, 1570. 1H-NMR (CDCl3) 7.30–7.34 (t, 4H, J = 7.40 Hz), 7.41–7.45 (tt, 2H, J = 1.21, 7.49 Hz), 7.77–7.81 (m, 6H), 8.10–8.12 (m, 1H), 8.20–8.22 (m, 1H). 13C-NMR (CDCl3) 127.72, 127.96, 128.58, 129.22, 130.65, 131.22, 132.89, 134.58, 134.68, 134.70, 138.75, 147.47, 171.55, 177.48, 178.30. ESI HRMS m/z 482.0005 ([M+Na]+ calcd 482.0004).
2-Dibenzoylamino-3-methoxy-1,4-naphthoquinone (3c). Yellow solid. (45%) Mp: 262–266 °C. IR (cm−1) 3012, 2953, 1675, 1651, 1605, 1578, 1270, 1249, 1218. 1H-NMR (CDCl3) 4.14 (s, 3H), 7.31–7.34 (dt, 4H, J = 1.60, 7.28 Hz), 7.41–7.45 (tt, 2H, J = 1.28, 7.44 Hz), 7.73–7.76 (m, 6H), 8.04–8.09 (m, 2H). 13C-NMR (CDCl3) 181.22, 180.43, 172.63, 154.71, 134.89, 134.55, 134.02, 132.61, 132.56, 131.67, 131.48, 130.86, 130.26, 129.04, 128.58, 128.54, 126.91, 126.73, 61.65. ESI HRMS m/z 434.0998 ([M+Na]+ calcd 434.1004).
2-Bis-(2-chlorobenzoyl)amino-3-chloro-1,4-naphthoquinone (3d). Yellow solid. (49%). Mp: 217–218 °C. IR (cm−1) 1720, 1681, 1618, 1588. 1H-NMR (CDCl3) 7.13–7.16 (d, 2H, J = 7.91 Hz), 7.21–7.25 (dt, 2H, J = 1.68, 7.51 Hz), 7.27–7.31 (dt, 2H, J = 1.30, 7.57), 7.79–7.85 (m, 2H), 7.87–7.89 (d, 2H, J = 4.75 Hz), 8.15–8.20 (m, 1H), 8.22–8.26 (m, 1H). 13C-NMR (CDCl3) 126.76, 126.93, 127.60, 127.80, 129.69, 130.54, 130.85, 131.37, 132.36, 132.52, 132.56, 132.75, 134.14, 134.75, 134.91, 142.65, 144.43, 177.13, 178.22. ESI HRMS m/z 505.9741 ([M+Na]+ calcd 505.9730).
2-Bis-(2-chlorobenzoyl)amino-3-bromo-1,4-naphthoquinone (3e). Yellow crystal (34%). Mp: 232–234 °C. IR (cm−1) 1728, 1688, 1671, 1588, 1468. 1H-NMR (CDCl3) 7.12–7.14 (d, 2H, J = 7.88 Hz), 7.19–7.23 (dd, 2H, J = 1.64, 7.56 Hz), 7.27–7.31 (dt, 2H, J = 1.28, 7.60 Hz), 7.80–7.85 (m, 2H), 7.93–7.94 (d, 2H, 5.2 Hz), 8.16–8.20 (m, 1H), 8.23–8.27 (m, 1H). 13C-NMR (CDCl3) 126.65, 127.66, 128.08, 129.63, 130.49, 130.81, 131.23, 132.25, 134.68, 134.80, 140.78, 145.81, 167.57, 177.26, 177.81. ESI HRMS m/z 549.9240 ([M+Na]+ calcd 549.9224).
2-Bis-(2-chlorobenzoyl)amino-3-methoxy-1,4-naphthoquinone (3f). Yellow solid. (64%) Mp: 195–200 °C. IR (cm−1) 3090, 2959, 1718, 1673, 1658, 1620, 1590, 1263, 1218, 1234, 1H-NMR (CDCl3) 4.30 (s, 3H), 7.19–7.28 (m, 6H), 7.73–7.80 (m, 4H), 8.07–8.12 (m, 2H). 13C-NMR (CDCl3) 180.88, 179.74, 168.21, 155.31, 134.30, 133.61, 132.08, 131.67, 131.10, 130.57, 130.16, 129.32, 128.67, 126.46, 126.27, 115.41, 103.74, 102.58, 61.47. ESI HRMS m/z 502.0224 ([M+Na]+ calcd 502.0225).
2-Bis-(3-chlorobenzoyl)amino-3-chloro-1,4-naphthoquinone (3g). Yellow solid. (31%). Mp: 258–260 °C. IR (cm−1) 3075, 1713, 1698, 1672, 1591, 1571. 1H-NMR (CDCl3) 7.27–7.31 (t, 2H, J = 7.85 Hz), 7.42–7.45 (ddd, 2H, J = 1.03, 2.09, 8.07 Hz), 7.60–7.63 (td, 2H, J = 1.07, 7.68 Hz), 7.70–7.71 (t, 2H, J = 1.82), 7.80–7.85 (m, 2H), 8.11–8.14 (m, 1H), 8.21–8.23 (m, 1H). 13C-NMR (CDCl3) 127.02, 127.93, 128.03, 129.34, 130.21, 130.75, 131.55, 133.29, 135.14, 135.21, 136.06, 143.00, 143.84, 170.20, 177.25, 178.66. ESI HRMS m/z 505.9741 ([M+Na]+ calcd 505.9730).
2-Bis-(3-chlorobenzoyl)amino-3-bromo-1,4-naphthoquinone (3h). Yellow solid (26%) Mp: 204–206 °C. IR (cm−1) 3074, 1698, 1671, 1589, 1566. 1H-NMR (CDCl3) 7.27–7.30 (t, 2H, J = 7.92 Hz), 7.41–7.44 (ddd, 2H, J = 1.04, 2.08, 8.04 Hz), 7.62–7.65 (td, 2H, J = 1.12, 7.72 Hz), 7.72–7.73 (t, 2H, J = 1.84 Hz), 7.78–7.85 (m, 2H), 8.10–8.14 (m, 1H), 8.20–8.24 (m, 1H). 13C-NMR (CDCl3) 127, 128.09, 128.40, 129.49, 130.25, 130.78, 131.49, 133.32, 135.15, 135.18, 135.24, 136.25, 139.56, 147.05, 170.21, 177.50, 178.43. ESI HRMS m/z 549.9236 ([M+Na]+ calcd 549.9224).
2-Bis-(3-chlorobenzoyl)amino-3-methoxy-1,4-naphthoquinone (3i). Yellow solid. (37%) Mp: 182–184 °C. IR (cm−1) 3107, 2960, 1707, 1689, 1670, 1657, 1604, 1572, 1283, 1266, 1239, 1218. 1H-NMR (CDCl3) 4.19 (s, 3H), 7.26–7.30 (t, 2H, J = 7.984 Hz), 7.40–7.43 (ddd, 2H, J = 1.04, 2.08, 8.04 Hz), 7.58–7.61 (td, 2H, J = 1.16, 7.72 Hz), 7.68–7.69 (t, 2H, J = 1.84 Hz), 7.73–7.77 (m, 2H), 8.05–8.09 (m, 2H). 13C-NMR (CDCl3) 180.66, 179.85, 170.63, 154.37, 135.97, 134.53, 134.35, 133.83, 132.37, 131.06, 130.29, 130.21, 129.58, 128.60, 126.58, 126.51, 126.32, 61.53. ESI HRMS m/z 502.0219 ([M+Na]+ calcd 502.0225).
2-Bis-(4-chlorobenzoyl)amino-3-chloro-1,4-naphthoquinone (3j). Yellow solid. (27%). Mp: 212–213 °C. IR (cm−1) 1737, 1714, 1696, 1673, 1589, 1571. 1H-NMR (CDCl3) 7.33–7.36 (td, 4H, J = 2.34, 8.54 Hz), 7.68–7.72 (td, 4H, J = 2.40, 8.47 Hz), 7.79–7.85 (m, 2H), 8 09–8.11 (dd, 1H, J = 2.50, 6.56 Hz), 8.20–8.22 (dd, 1H, J = 2.40, 6.66 Hz). 13C-NMR (CDCl3) 127.72, 127.80, 129.18, 130.34, 130.50, 131.32, 132.52, 134.92, 134.95, 139.67, 142.46, 143.87, 170.40, 177.05, 178.59. ESI MS m/z 505.975 ([M+Na]+ calcd 505.973).
2-Bis-(4-chlorobenzoyl)amino-3-bromo-1,4-naphthoquinone (3k). Yellow solid. (34%). Mp: 266–269 °C. IR (cm−1) 3096, 1703, 1661, 1586. 1H-NMR (CDCl3) 7.33–7.36 (td, 4H, J = 2.16, 8.47 Hz), 7.70–7.73 (td, 4H, J = 2.37, 8.53 Hz), 7.79–7.82 (m, 2H), 8.08–8.11 (m, 1H), 8.20–8.22(m, 1H). 13C-NMR (CDCl3) 127.80, 128.09, 129.13, 130.41, 130.46, 131.17, 132.66, 134.84, 134.90, 138.94, 139.61, 146.98, 170.32, 177.21, 178.28. ESI MS m/z 549.923 ([M+Na]+ calcd 549.9224).
2-Bis-(4-chlorobenzoyl)amino-3-methoxy-1,4-naphthoquinone (3l). Yellow solid. (64%) Mp: 170–172 °C. IR (cm−1) 3100, 2958, 1722, 1687, 1668, 1687, 1652, 1589, 1575, 1274. 1H-NMR (CDCl3) 4.15 (s, 3H), 7.32–7.35 (td, 4H, J = 2.36, 8.64 Hz), 7.66–7.70 (td, 4H, J = 2.36, 8.68 Hz), 7.74–7.76 (m, 2H), 8.05–8.08 (m, 2H). 13C-NMR (CDCl3) 181.11, 180.45, 171.50, 154.73, 139.32, 134.80, 134.32, 133.05, 131.52, 131.08, 130.75, 130.30, 129.19, 127.04, 126.97, 61.93. ESI HRMS m/z 502.0223 ([M+Na]+ calcd 502.0225).
2-Bis-(4-fluorobenzoyl)amino-3-chloro-1,4-naphthoquinone (3m). Yellow solid. (56%). Mp: 284–286 °C. IR (cm−1) 3074, 1719, 1689, 1672, 1591. 1H-NMR (CDCl3) 7.00–7.06 (tt, 4H, J = 2.85, 8.71 Hz), 7.75–7.85 (m, 6H), 8.10–8.12 (m, 1H), 8.20–8.22 (m, 1H). 13C-NMR (CDCl3) 116.08 (d, 2JF,C = 22.2 Hz, C-C-F), 116.41, 126.65, 126.96, 127.67, 127.77, 130.53, 130.57, 130.58, 131.35, 131.66 (d, 3JF,C = 9.4 Hz, C-C-C-F), 132.75, 134.88, 142.42, 144.13, 165.41(d, 1JF,C = 255.99 Hz, C-F), 170.33, 177.13, 178.63. ESI MS m/z 474.034 ([M+Na]+ calcd 474.032).
2-Bis-(4-fluorobenzoyl)amino-3-bromo-1,4-naphthoquinone (3n). Orange-yellow solid (66%). Mp: 170–172 °C. IR (cm−1) 1719, 1670, 1596, 1505. 1H-NMR (CDCl3) 7.03–7.07 (tt, 4H, J = 2.04, 8.68 Hz), 7.80–7.84 (m, 6H), 8.11–8.14 (m, 1H), 8.23–8.25 (m, 1H).13C-NMR (CDCl3) 115.68 (d, 2JF,C = 22.2 Hz, C-C-F), 127.4, 127.71, 130.18, 130.30, 130.33, 130.85, 131.39 (d, 3JF,C = 9.3 Hz, C-C-C-F), 131.44, 134.46, 134.50, 138.52, 146.90, 165.03 (d, 1JF,C = 255.92 Hz, C-F), 169.91, 176.96, 177.97. ESI HRMS m/z 517.9785 ([M+Na]+ calcd 517.9815).
2-Bis-(4-fluorobenzoyl)amino-3-methoxy-1,4-naphthoquinone (3o). Yellow solid. (14%) Mp: 177–179 °C. IR (cm−1) 3073, 3015, 2957, 1708, 1672, 1652, 1614, 1600, 1589, 1269. 1H-NMR (CDCl3) 8.09–8.04 (m, 2H), 7.78–7.74 (m, 6H), 7.03–7.01 (t, 4H, J = 8.56 Hz), 4.15 (s, 3H). 13C-NMR (CDCl3) 61.63, 115.82 (d, 2JF,C = 22.5 Hz, C-C-F), 126.70, 126.78, 130.60, 130.79, 130.82, 131.22, 131.30 (d, 3JF,C = 8.9 Hz, C-C-C-F), 131.31, 134.03, 134.52, 146.62, 154.51, 165.18 (d, 1JF,C = 255.2 Hz, C-F), 166.45, 171.20, 180.29, 180.95. ESI HRMS m/z 470.0807 ([M + Na]+ calcd 470.0816).
2-Bis-(4-tert-butylbenzoyl)amino-3-chloro-1,4-naphthoquinone (3p). Yellow solid.(28%). Mp: 257–260 °C. IR (cm−1) 2965, 2901, 2868, 1701, 1673, 1603, 1592, 1572. 1H-NMR (CDCl3) 1.25 (s, 18H), 7.30–7.32 (td, 4H, J = 1.81, 8.53 Hz), 7.67–7.69(td, 4H, J = 1.86, 8.57 Hz), 7.78–7.81 (m, 2H), 8.09–8.13 (m, 1H), 8.22–8.18 (m, 1H). 13C-NMR (CDCl3) 30.96, 35.06, 125.51, 127.60, 127.65, 129.14, 130.82, 131.45, 131.71, 134.62, 134.68, 142.09, 144.58, 156.57, 171.66, 177.51, 178.67. ESI HRMS m/z 550.1740 ([M+Na]+ calcd 550.1761).
2-Bis-(4-tert-butylbenzoyl)amino-3-bromo-1,4-naphthoquinone (3q). Yellow solid. (58%) Mp: 244–250 °C. IR (cm−1) 2965, 1699, 1674, 1604, 1270, 1186. 1H-NMR (CDCl3) 1.24 (s, 18H), 7.29–7.31 (d, 4H, J = 8.40 Hz), 7.68–7.70 (d, 4H, J = 8.4 Hz), 7.77–7.80 (m, 2H), 8.09–8.11 (m, 1H), 8.19–8.21 (m, 1H). 13C-NMR (CDCl3) 30.75, 34.85, 125.26, 127.52, 127.69, 129.03, 130.58, 131.10,m131.65, 134.36, 134.40, 138.26, 147.50, 156.30, 171.39, 177.46, 178.15. ESI HRMS m/z 1165.3845 ([dimer+Na]+ calcd 1165.2614).
2-Bis-(4-tert-butylbenzoyl)amino-3-methoxy-1,4-naphthoquinone (3r). Yellow solid. (37%) Mp: 222–224 °C. IR (cm−1) 2964, 2905, 2868, 1693, 1674, 1662, 1605, 1271, 1220, 1187. 1H-NMR (CDCl3) 1.25 (s, 18H), 4.12 (s, 3H), 7.30–7.32 (d, 4H, J = 8.44 Hz), 7.65–7.67 (d, 4H, J = 8.40 Hz), 7.71–7.75 (m, 2H), 8.04–8.10 (m, 2H). 13C-NMR (CDCl3) 30.97, 31.02, 34.98, 61.46, 125.35, 125.83, 126.53, 126.81, 128.87, 130.49, 130.87, 131.40, 131.96, 132.04, 133.81, 134.33, 154.64, 156.03, 172.52, 180.39, 181.22. ESI HRMS m/z 524.2449 ([M+Na]+ calcd 524.2437).
2-Bis-(4-methoxybenzoyl)amino-3-chloro-1,4-naphthoquinone (3s). Yellow solid. (48%). Mp: 283–287 °C. IR (cm−1) 3019, 1698, 1668, 1599, 1574, 1508. 1H-NMR (CDCl3).3.81 (s, 6H), 6.80–6.84 (td, 4H, J = 2.86, 8.95 Hz), 7.73–7.82 (m, 6H), 8.09–8.11 (m, 1H), 8.19–8.21 (m, 1H). 13C-NMR (CDCl3) 55.48, 113.98, 114.21, 126.76, 127.57, 127.64, 130.38, 130.79, 131.41, 131.48, 134.61, 134.66, 141.69, 144.95, 163.34, 171.03, 177.48, 178.77. ESI MS m/z 498.074 ([M+Na]+ calcd 498.072).
2-Bis-(4-methoxybenzoyl)amino-3-bromo-1,4-naphthoquinone (3t). Yellow solid. (70%). Mp: 205–210 °C. IR (cm−1) 2839, 1694, 1669, 1598, 1574, 1509, 1167. 1H-NMR (CDCl3). 3.80 (s, 6H), 6.80–6.82 (d, 4H, J = 8.48 Hz), 7.75–7.78 (m, 6H), 8.07–8.09 (m, 1H), 8.18–8.20 (m, 1H). 13C-NMR (CDCl3) 55.43, 113.89, 126.86, 127.67, 127.82, 130.70, 131.21, 131.52, 134.52, 134.54, 138.01, 148.01, 163.25, 170.92, 177.60, 178.40. ESI MS m/z 557.9965 ([M+K]+ calcd 557.9955).
2-Bis-(3,4,5-trimethoxybenzoyl)amino-3-chloro-1,4-naphthoquinone (3u). Orange crystals (51%). Mp: 171–172 °C. IR (cm−1) 3015, 2939, 2838, 1704, 1675, 1586, 1122. 1H-NMR (CDCl3) 3.81 (s, 12H), 3.84 (s, 6H), 7.02 (s, 4H), 7.81–7.84 (m, 2H), 8.12–8.14 (m, 1H), 8.22–8.24 (m, 1H). 13C-NMR (CDCl3) 56.27, 56.35, 60.93, 127.62, 127.77, 129.31, 130.69, 131.39, 134.86, 142.06, 142.27, 144.45, 153.01, 171.08, 177.27, 178.84. ESI MS m/z 618.118 ([M+Na]+ calcd 618.114).
2-N-(4-Chlorobenzoyl))-amino-3-chloro-1,4-naphthoquinone (4). 2-Amino-3-chloro-1,4-naphthoquinone (302 mg, 1.45 mmol) was dissolved in freshly distilled THF (15 mL). NaH (104 mg, 4.33 mmol) was added to the solution and the mixture was stirred at room temperature for 30 mins. p-Chlorobenzoyl chloride (0.27 mL, 2.14 mmol) was added and the mixture was stirred for 5 mins. THF was removed under vacuum and the mixture was extracted (see general experimental for work up). The crude was recrystallized in EtOH (20 mL) then triturated in ethyl acetate to obtain the 4 in 40% yield. IR (cm−1) 3330.36, 1693.64, 1659.97, 1609.37. 1H-NMR (CDCl3) 7.50–7.54 (td, J = 2.66, 8.45 Hz, 2H), 7.76–7.84 (m, 2H), 7.91–7.94 (td, J = 2.54, 8.58 Hz, 2H), 8.13–8.16 (dd, J = 1.86, 7.15 Hz, 1H), 8.22–8.24 (dd, J = 1.54, 7.46 Hz, 1H), 8.30 (s, 1H). 13C-NMR (DSMO-d6) 127.21, 127.30, 129.14, 129.91, 130.73, 131.57, 131.92, 132.68, 135.12, 137.16, 137.96, 142.11, 164.73, 177.93, 178.91. ESI HRMS m/z 346.0017 ([M+H]+ calcd 346.0038).
2-(N-Benzoyl-N-(4-chlorobenzoyl))-amino-3-chloro-1,4-naphthoquinone (5). Compound 4 (101 mg, 0.292 mmol) was dissolved in THF (15 mL). NaH (14 mg, 0.583 mmol) was added followed by benzoyl chloride (0.07 mL, 0.604 mmol). The resulting mixture was stirred at room temperature for 26 hours. THF was removed under vacuum and the mixture was extracted (see general experiment for work up). The crude was purified by column chromatography with silica gel in CH2Cl2 to obtain a yellow solid in 43% yield. IR (cm−1) 3093, 1705, 1693, 1673, 1587, 1571, 1521. 1H-NMR (CDCl3) 7.30–7.33 (td, 2H, J = 1.89, 6.72 Hz), 7.33–7.37 (t, J = 7.98 Hz, 2H), 7.45–7.47 (t, 1H, J = 7.46 Hz), 7.69–7.72 (td, 2H, J = 1.96, 8.60 Hz), 7.73–7.76 (td, 2H, J = 1.41, 8.49 Hz), 7.79–7.82 (m, 1H), 8.10–8.13 (m, 1H), 8.20–8.22 (m, 1H). 13C-NMR (CDCl3) 127.68, 127.73, 128.76, 129.00, 129.06, 130.63, 131.37, 133.21, 134.82, 124.84, 171.34, 177.19, 178.60. ESI MS m/z 472.0097 ([M+Na]+ calcd 472.0119).
2-N-acteylamino-3-chloro-1,4-naphthoquinone (6). 2-Amino-3-chloro-1,4-naphthoquinone (305 mg, 1.47 mmol) was stirred for 10 mins at room temperature in acetic anhydride (9 mL, 95.39 mmol). Conc. sulfuric acid (1 drop) was added and the reaction mixture was stirred to obtain a yellow precipitate in 64% yield. IR (cm−1) 3308.59, 1711.06, 1607.38, 1586.41, 1475.28, 1198.03. 1H-NMR (CDCl3) 2.32 (s, 3H), 7.68 (s, 1H), 7.76–7.83 (m, 2H), 8.12–8.15 (ddd, 1H, J = 1.88, 2.20, 7.20 Hz), 8.20–8.22 (ddd, 1H, J = 1.44, 2.68, 7.08 Hz). 13C-NMR (CDCl3) 24.18, 127.09, 127.57, 130.26, 131.58, 134.16, 134.83. MALDI MS m/z 273.1471 ([M+Na]+ calcd 272.0090).
2-(N-acetyl-N-(4-chlorobenzoyl))-amino-3-chloro-1,4-naphthoquinone (
7). Compound
6 (300 mg, 1.2 mmol) was dissolved in THF (26 mL). NaH (75.6 mg, 1.88 mmol) was added to the solution and the mixture was stirred at room temperature for 15 min. 4-Chlorobenzoyl chloride (0.2 mL, 1.56 mmol) was added and the mixture was stirred at room temperature for 25 hrs. THF was removed under vacuum and the mixture was extracted (see general experiment for work up). The crude was purified by triturating in 50% ether/hexane mixture, followed by recrystallization from hexane (1.2 mg of crude/mL of hexane) to obtain a yellow solid in 41% yield. Mp: 134–136 °C. IR (cm
−1) 1673.43, 1702.76, 1591.38, 1254.29, 1197.10.
1H-NMR (CDCl
3) 2.56 (s, 3H), 7.31–7.35 (td, 2H,
J = 2.32, 8.72 Hz), 7.59–7.62 (td, 2H,
J = 2.36, 8.52 Hz), 7.79–7.82 (m, 2H), 8.11–8.16 (m, 2H).
13C-NMR (CDCl
3) 25.33, 127.67, 129.02, 129.54, 130.54, 131.16, 132.67, 134.76, 134.84, 139.39, 143.32, 143.42, 169.66, 171.94, 176.85, 178.48. ESI MS
m/z 410.0009 ([M+Na]
+ calcd 409.9963). Structural information of compound
7 has been deposited with the CCDC as CCDC894544. This data is available free of charge from
www.ccdc.com.ac.uk/conts/rtrieving.html (or from the Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 IEZ, UK).