3.2. General Procedure for the Synthesis of Bisindolyl Tetrahydrocarbazoles 3 and 4
2 mmol of the freshly distilled succinaldehyde 2 was dissolved in 15 mL acetic acid (100%). After addition of 5 mmol of the indole derivative, the solution color changed. The mixture was stirred for at least 24 h at room temperature protected from light. The reaction proceeding was followed by TLC, indicating the formation of two products. When no more changes in the detectable product formation were observed within the mixture according to TLC, the work-up procedure started with adjusting the pH-value to 6–7 using sodium hydroxide solution (10%) under precipitate formation. The precipitate was filtered and washed with distilled water. Then it was dissolved in ethyl acetate and dried over magnesium sulfate. After filtration, the solvent was removed in vacuum. The oily residue was separated by column chromatography over silica gel to result in eluated fractions containing each compounds 3 and 4, respectively.
(1R,4S)-1,4-Di(1H-indol-3-yl)-2,3,4,9-tetrahydro-1H-carbazole (3a). Yield 21%, light pink powder; mp 167–168 °C; 1H NMR (DMSO-d6) δ = 10.89 (d, 3JN′/2′ = 2.4 Hz, 1H, N′-H), 10.69 (d, 3JN″/2″ = 2.3 Hz, 1H, N″-H), 10.45 (s, 1H, N-H), 7.61 (dbr, 3J4″/5″ = 7.9 Hz, 4J4″/6″, 1H, 4″-H), 7.39 (dbr, 3J4′/5′ = 7.9 Hz, 4J4′/6′, 1H, 4′-H), 7.36 (dd, 3J7′/6′ = 8.2 Hz, 4J7′/5′ = 0.9 Hz, 1H, 7′-H), 7.33 (dd, 3J7″/6″ = 8.2 Hz, 4J7″/5″ = 0.9 Hz, 1H, 7″-H), 7.18 (dd, 3J8/7 = 7.9 Hz, 4J8/6 = 0.9 Hz, 1H, 8-H), 7.08 (d, 3J2′/N′ = 2.4 Hz, 1H, 2′-H), 7.04 (ddd, 3J6′/7″; 6″/7″ = 7.9 Hz, 3J6′/5′; 6″/5″ = 7.4 Hz, 4J6′/4′; 6″/4″ = 0.9 Hz, 2H: 6″-H; 6′-H), 6.94 (ddd, 3J5″/4″ = 7.9 Hz, 3J5″/6″ = 7.4 Hz, 4J5″/7″ = 0.9 Hz, 1H, 5″-H), 6.90 (ddd, 3J5′/4′ = 7.9 Hz, 3J5′/6′ = 7.4 Hz, 4J5′/7′ = 0.9 Hz, 1H, 5′-H), 6.89 (dd, 3J5/6 = 8.2 Hz, 4J5/7 = 1.2 Hz, 1H, 5-H), 6.87 (ddd, 3J7/8 = 7.9 Hz, 3J7/6 = 7.4 Hz, 4J7/5 = 1.2 Hz, 1H, 7-H), 6.81 (d, 3J2″/N″ = 2.3 Hz, 1H, 2″-H), 6.70 (ddd, 3J6/5 = 8.2 Hz, 3J6/7 = 7.4 Hz, 4J6/8 = 0.9 Hz, 1H, 6-H), 4.55 (t, 3J4/3,3 = 5.3 Hz, 1H, 4-H), 4.50 (t, 3J1/2,2 = 6.4 Hz, 1H, 1-H), 2.17–2.09 (m, 2H, 3,3-H), 2.08–2.02 (m, 2H, 2,2-H); m/z (ESI) 400.37 (100, [M−H]−).
(1R,4S)-6-Chloro-1,4-bis(5-chloro-1H-indol-3-yl)-2,3,4,9-tetrahydro-1H-carbazole (3b). Yield 16%, light beige powder; mp 149–152 °C; 1H NMR (DMSO-d6) δ = 11.18 (d, 3JN′/2′ = 2.3 Hz, 1H, N′-H), 11.03 (d, 3JN″/2″ = 2.4 Hz, 1H, N″-H), 10.77 (s, 1H, N-H), 7.61 (d, 4J4″/6″ = 2.1 Hz, 1H, 4″-H), 7.44 (d, 4J4′/6′ = 2.1 Hz, 1H, 4′-H), 7.40 (d, 3J7′/6′ = 8.5 Hz, 1H, 7′-H), 7.38 (d, 3J7″/6″ = 8.5 Hz, 1H, 7″-H), 7.23 (d, 3J8/7 = 8.5 Hz, 1H, 8-H), 7.17 (d, 3J2′/N′ = 2.3 Hz, 1H, 2′-H), 7.07 (dd, 3J6′/7′ = 8.5 Hz, 4J6′/4′ = 2.1 Hz, 1H, 6′-H), 7.07 (dd, 3J6″/7″ = 8.5 Hz, 4J6″/4″ = 2.1 Hz, 1H, 6″-H), 6.93 (dd, 3J7/8 = 8.5 Hz, 4J7/5 = 2.1 Hz, 1H, 7-H), 6.92 (d, 3J2″/N″ = 2.4 Hz, 1H, 2″-H), 6.86 (d, 4J5/7 = 2.1 Hz, 1H, 5-H), 4.55 (t, 3J4/3,3 = 5.1 Hz, 1H, 4-H), 4.52 (t, 3J1/2,2 = 5.1 Hz, 1H, 1-H), 2.23–2.12 (m, 2H, 3,3-H), 2.05–1.93 (m, 2H, 2,2-H); m/z (ESI) 502.17 (100, [M−H]−); 504.19 (86, [M−H]−); 506.17 (29, [M−H]−).
(1R,4S)-7-Chloro-1,4-bis(6-chloro-1H-indol-3-yl)-2,3,4,9-tetrahydro-1H-carbazole (3c). Yield 19%, beige powder; mp 172–173 °C; 1H NMR (DMSO-d6) δ = 11.07 (d, 3JN′/2′ = 2.3 Hz, 1H, N′-H), 10.89 (d, 3JN″/2″ = 2. Hz, 1H, N″-H), 10.55 (s, 1H, N-H), 7.41 (d, 4J7′/5′ = 2.0 Hz, 1H, 7′-H), 7.37 (d, 4J7″/5″ = 2.2 Hz, 1H, 7″-H), 7.33 (d, 3J4″/5″ = 8.5 Hz, 1H, 4″-H), 7.22 (d, 3J4′/5′ = 8.5 Hz, 1H, 4′-H), 7.14 (d, 4J8/6 = 1.9 Hz, 1H, 8-H), 7.13 (d, 4J2′/N′ = 2.4 Hz, 1H, 2′-H), 7.01 (d, 4J2″/N″ = 2.3 Hz, 1H, 2″-H), 6.90 (dd, 3J5′/4′ = 8.5 Hz, 4J5′/7′ = 1.9 Hz, 1H, 5′-H), 6.85 (dd, 3J5″/4″ = 8.5 Hz, 4J5″/7″ = 2.0 Hz, 1H, 5″-H), 6.69 (d, 3J5/6 = 8.5 Hz, 1H, 5-H), 6.65 (dd, 3J6/5 = 8.5 Hz, 4J6/8 = 1.9 Hz, 1H, 6-H), 4.58 (t, J4/3,3 = 5.3 Hz, 1H, 4-H), 4.55 (t, J1/2,2 = 5.4 Hz, 1H, 1-H), 2.23–2.17 (m, 2H, 3,3-H), 2.04–1.95 (m, 2H, 2,2-H); m/z (ESI) 502.23 (100, [M−H]−); 504.21 (85, [M−H]−).
(1R,4S)-6-Bromo-1,4-bis(5-bromo-1H-indol-3-yl)-2,3,4,9-tetrahydro-1H-carbazole (3d). Yield 24%, light beige powder; mp 146–148 °C; 1H NMR (DMSO-d6) δ = 11.19 (d, 3JN′/2′ = 2.3 Hz, 1H, N′-H), 11.05 (d, 3JN″/2″ = 2.4 Hz, 1H, N″-H), 10.77 (s, 1H, N-H), 7.76 (d, 4J4″/6″ = 2.0 Hz, 1H, 4″-H), 7.57 (d, 4J4′/6′ = 1.9 Hz, 1H, 4′-H), 7.36 (d, 3J7″/6″ = 8.6 Hz, 1H, 7″-H), 7.34 (d, 3J7′/6′ = 8.6 Hz, 1H, 7′-H), 7.19 (d, 3J8/7′ = 8.6 Hz, 1H, 8-H), 7.18 (dd, 3J6″/7″ = 8.6 Hz, 4J6″/4″ = 2.0 Hz, 1H, 6″-H), 7.17(dd, 3J6′/7′ = 8.6 Hz, 4J6′/4′ = 1.9 Hz, 1H, 6′-H), 7.16 (d, 3J2′/N′ = 2.3 Hz, 1H, 2′-H), 7.04 (dd, 3J7/8 = 8.6 Hz, 4J7/5′ = 2.0 Hz, 1H, 7-H), 7.01 (d, 4J5/7 = 2.0 Hz, 1H, 5-H), 6.88 (d, 3J2″/N″ = 2.4 Hz, 1H, 2″-H), 4.55 (t, J1/2,2 = 5.2 Hz, 1H, 1-H), 4.51 (t, J4/3,3 = 5.2 Hz, 1H, 4-H), 2.18–2.07 (m, 2H, 3,3-H), 2.07–1.94 (m, 2H, 2,2-H); m/z (ESI) 636.12 (100, [M−H]−); 638.11 (92, [M−H]−); 640.11 (34, [M−H]−); 634.18 (30, [M−H]−).
(1R,4S)-7-Bromo-1,4-bis(5-bromo-1H-indol-3-yl)-2,3,4,9-tetrahydro-1H-carbazole (3e). Yield 12%, light pink powder; mp 151–153 °C; 1H NMR (DMSO-d6) δ = 11.08 (d, 3JN′/2′ = 2.4 Hz, 1H, N′-H), 10.88 (d, 3JN″/2″ = 2.4 Hz, 1H, N″-H), 10.71 (s, 1H, N-H), 7.57 (d, 4J7′/5′ = 1.8 Hz, 1H, 7′-H), 7.53 (d, 4J7″/5″ = 1.8 Hz, 1H, 7″-H), 7.52 (d, 3J4″/5″ = 8.3 Hz, 1H, 4″-H), 7.36 (d, 4J8/6 = 1.8 Hz, 1H, 8-H), 7.33 (d, 3J4′/5′ = 8.3 Hz, 1H, 4′-H), 7.13 (d, 3J2′/N′ = 2.4 Hz, 1H, 2′-H), 7.07 (dd, 3J5″/4″ = 8.3 Hz, 4J5″/7″ = 1.8 Hz, 1H, 5″-H), 7.07 (dd, 3J5′/4′ = 8.3 Hz, 4J5′/7′ = 1.8 Hz, 1H, 5′-H), 6.88 (d, 3J2″/N″ = 2.4 Hz, 1H, 2″-H), 6.86 (dd, 3J6/5 = 8.4 Hz, 4J6/8 = 1.8 Hz, 1H, 6-H), 6.80 (d, 3J5/6 = 8.4 Hz, 1H, 5-H), 4.54 (t, 3J1/2,2 = 5.5 Hz, 1H, 1-H), 4.51 (t, 3J4/3,3 = 5.5 Hz, 1H, 4-H), 2.25–2.18 (m, 2H, 3,3-H), 2.03–1.93 (m, 2H, 2,2-H); m/z (ESI) 638.09 (100, [M−H]−); 636.13 (93, [M−H]−); 634.17 (39, [M−H]−); 640.06 (34, [M−H]−).
(1R,4S)-6-(Benzyloxy)-1,4-bis(5-(benzyloxy)-1H-indol-3-yl)-2,3,4,9-tetrahydro-1H-carbazole (3f). Yield 22%, red brownish powder; mp 89–91 °C; 1H NMR (DMSO-d6) δ = 10.71 (d, 3JN′/2′ = 2.3 Hz, 1H, N′-H), 10.56 (d, 3JN″/2″ = 2.4 Hz, 1H, N″-H), 10.26 (s, 1H, N-H), 7.40 (dd, 3J2,6-Ph′/3,5-Ph′ = 7.9 Hz, 4J2,6-Ph′/4-Ph′ = 1.1 Hz, 2H, 2,6-Ph′-H), 7.40–7.20 (m, 13H, Ar-H), 7.25 (d, 3J7″/6″ = 8.6 Hz, 1H, 7″-H), 7.24 (d, 3J7′/6′ = 8.6 Hz, 1H, 7′-H), 7.08 (d, 3J8/7 = 8.6 Hz, 1H, 8-H), 7.06 (d, 4J4′/6′ = 2.3 Hz, 1H, 4′-H), 6.94 (d, 3J2′/N′ = 2.3 Hz, 1H, 2′-H), 6.81 (d, 3J2″/N″ = 2.4 Hz, 1H, 2″-H), 6.79 (dd, 3J6″/7″ = 8.6 Hz, 4J6″/4″ = 2.4 Hz, 1H, 6″-H), 6.77 (dd, 3J6′/7′ = 8.6 Hz, 4J6′/4′ = 2.3 Hz, 1H, 6′-H), 6.75 (d, 4J4″/6″ = 2.4 Hz, 1H, 4″-H), 6.61 (dd, 3J7/8 = 8.6 Hz, 4J7/5 = 2.5 Hz, 1H, 7-H), 6.47 (d, 4J5/7 = 2.5 Hz, 1H, 5-H), 5.01 (s, 2H, O-CH2-Ph′), 4.84 (s, 2H, O-CH2-Ph″), 4.76–4.66 (m, 2H, O-CH2-Ph), 4.52–4.45 (m, 2H, 1-H; 4-H), 2.20–2.10 (m, 2H, 3,3-H), 2.01–1.81 (m, 2H, 2,2-H); m/z (ESI) 742.33 (100, [M+Na]+); 720.26 (13, [M+H]+).
3,3′-((1R,4S)-6-Cyano-2,3,4,9-tetrahydro-1H-carbazole-1,4-diyl)bis(1H-indole-5-carbonitrile) (3h). Yield 8%, light pink powder; mp 184–186 °C; 1H NMR (DMSO-d6) δ = 11.60 (d, 3JN′/2 = 2.4 Hz, 1H, N′-H), 11.44 (d, 3JN″/2″ = 2.4 Hz, 1H, N″-H), 11.15 (s, 1H, N-H), 8.14 (d, 4J4″/6″ = 1.5 Hz, 1H, 4″-H), 8.04 (d, 4J4′/6′ = 1.5 Hz, 1H, 4′-H), 7.56 (d, 3J7′/6′ = 8.5 Hz, 1H, 7′-H), 7.54 (d, 3J7″/6″ = 8.6 Hz, 1H, 7″-H), 7.44 (dd, 3J6′/7′ = 8.5 Hz, 4J6′/4′ = 1.5 Hz, 1H, 6′-H), 7.43 (dd, 3J6″/7″ = 8.6 Hz, 4J6″/4″ = 1.5 Hz, 1H, 6″-H), 7.39 (d, 3J8/7 = 8.5 Hz, 1H, 8-H), 7.31 (dd, 3J7/8 = 8.5 Hz, 4J7/5 = 1.6 Hz, 1H, 7-H), 7.30 (d, 3J2′/N′ = 2.4 Hz, 1H, 2′-H), 7.29 (d, 4J5/7 = 1.6 Hz, 1H, 5-H), 7.05 (d, 3J2″/N″ = 2.4 Hz, 1H, 2″-H), 4.70 (t, 3J4/3,3 = 5.1 Hz, 1H, 4-H), 4.67 (t, 3J1/2,2 = 5.2 Hz, 1H, 1-H), 2.28–2.14 (m, 2H, 3,3-H), 2.05–1.91 (m, 2H, 2,2-H); m/z (ESI) 475.26 (100, [M−H]−).
(1S,4S)-1,4-Di(1H-indol-3-yl)-2,3,4,9-tetrahydro-1H-carbazole (4a). Yield 19%, white powder; mp 152–154 °C; 1H NMR (DMSO-d6) δ = 10.87 (d, 3JN′/2′ = 2,4 Hz, 1H, N′-H), 10.69 (d, 3JN″/2″ = 2,3 Hz, 1H, N″-H), 10.39 (s, 1H, N-H), 7.45 (dbr, 3J4″/5″ = 7.9 Hz, 4J4″/6″, 1H, 4″-H), 7.36 (dbr, 3J7′/6′ = 8.1 Hz, 4J7′/5′, 1H, 7′-H), 7.34 (dbr, 3J7″/6″ = 8.1 Hz, 4J7″/5″, 1H, 7″-H), 7.30 (dbr, 3J4′/5′ = 7.9 Hz, 4J4′/6′, 1H, 4′-H), 7.15 (dbr, 3J8/7 = 8.1 Hz, 4J8/6, 1H, 8-H), 7.05 (ddd, 3J6′/7′ = 8.1 Hz, 3J6′/5′ = 6.9 Hz, 4J6′/4′ = 1.1 Hz, 1H, 6′-H), 7.03 (ddd, 3J6″/7″ = 8.1 Hz, 3J6″/5″ = 6.9 Hz, 4J6″/4″ = 1.0 Hz, 1H, 6″-H), 6.99 (d, 3J2′/N′ = 2.4 Hz, 1H, 2′-H), 6.89 (ddd, 3J5″/4″ = 7.9 Hz, 3J5″/6″ = 6.9 Hz, 4J5″/7″ = 1.0 Hz, 1H, 5″-H), 6.87 (ddd, 3J5′/4′ = 7.9 Hz, 3J5′/6′ = 6.9 Hz, 4J5′/7′ = 1.0 Hz, 1H, 5′-H), 6.85 (d, 3J2″/N″ = 2.3 Hz, 1H, 2″-H), 6.84 (ddd, 3J7/8 = 8.1 Hz, 3J7/6 = 7.0 Hz, 4J7/5 = 1.0 Hz, 1H, 7-H), 6.81 (dbr, 3J5/6 = 8.0 Hz, 4J5/7, 1H, 5-H), 6.63 (ddd, 3J6/5 = 8.0 Hz, 3J6/7 = 7.0 Hz, 4J6/8 = 1.0 Hz, 1H, 6-H), 4.59 (t, 3J1/2,2 = 4.9 Hz, 1H, 1-H), 4.59 (t, 3J4/3,3 = 4.9 Hz, 1H, 4-H), 2.27–2.20 (m, 2H, 3,3-H), 2.03–1.96 (m, 2H, 2,2-H); m/z (ESI) 400.31 (100, [M−H]−); 801.24 (42, [2M−H]−).
(1S,4S)-6-Chloro-1,4-bis(5-chloro-1H-indol-3-yl)-2,3,4,9-tetrahydro-1H-carbazole (4b). Yield 12%, beige powder; mp 167–170 °C; 1H NMR (DMSO-d6) δ = 11.13 (d, 3JN′/2′ = 2.3 Hz, 1H, N′-H), 10.97 (d, 3JN″/2″ = 2.3 Hz, 1H, N″-H), 10.65 (s, 1H, N-H), 7.39 (d, 3J7′/6′ = 8.5 Hz, 1H, 7′-H), 7.38 (d, 4J4″/6″ = 2.0 Hz, 1H, 4″-H), 7.36 (d, 3J7″/6″ = 8.5 Hz, 1H, 7″-H), 7.29 (d, 4J4′/6′ = 2.0 Hz, 1H, 4′-H), 7.16 (d, 3J8/7 = 8.5 Hz, 1H, 8-H), 7.13 (d, 3J2′/N′ = 2.3 Hz, 1H, 2′-H), 7.05 (dd, 3J6′/7′ = 8.5 Hz, 4J6′/4′ = 2.0 Hz, 1H, 6′-H), 7.04 (d, 3J2″/N″ = 2.3 Hz, 1H, 2″-H), 7.02 (dd, 3J6″/7″ = 8.5 Hz, 4J6″/4 = 2.0 Hz, 1H, 6″-H), 6.85 (dd, 3J7/8 = 8.5 Hz, 4J7/5 = 2.1 Hz, 1H, 7-H), 6.70 (d, 4J5/7 = 2.1 Hz, 1H, 5-H), 4.64–4.60 (m, 1H, 1-H), 4.58–4.54 (m, 1H, 4-H), 2.23–2.17 (m, 2H, 3,3-H), 2.00–1.93 (m, 2H, 2,2-H); m/z (ESI) 502.38 (100, [M−H]−); 504.32 (92, [M−H]−).
(1S,4S)-7-Chloro-1,4-bis(6-chloro-1H-indol-3-yl)-2,3,4,9-tetrahydro-1H-carbazole (4c). Yield 13%, beige powder; mp 159–161 °C; 1H NMR (DMSO-d6) δ = 11.07 (d, 3JN′/2′ = 2.4 Hz, 1H, N′-H), 10.88 (d, 3JN″/2″ = 2.4 Hz, 1H, N″-H), 10.70 (s, 1H, N-H), 7.57 (d, 3J4″/5″ = 8.5 Hz, 1H, 4″-H), 7.42 (d, 4J7′/5′ = 1.9 Hz, 1H, 7′-H), 7.39 (d, 3J4′/5′ = 8.5 Hz, 1H, 4′-H), 7.39 (d, 4J7″/5″ = 1.9 Hz, 1H, 7″-H), 7.21 (d, 4J8/6 = 1.9 Hz, 1H, 8-H), 7.14 (d, 3J2′/N′ = 2.4 Hz, 1H, 2′-H), 6.96 (dd, 3J5″/4″ = 8.5 Hz, 4J5″/7″ = 1.9 Hz, 1H, 5″-H), 6.95 (dd, 3J5′/4′ = 8.5 Hz, 4J5′/7′ = 1.9 Hz, 1H, 5′-H), 6.89 (d, 3J2″/N″ = 2.4 Hz, 1H, 2″-H), 6.84 (d, 3J5/6 = 8.4 Hz, 1H, 5-H), 6.75 (dd, 3J6/5 = 8.4 Hz, 3J6/8 = 1.9 Hz, 1H, 6-H), 4.55–4.47 (m, 2H: 1- H; 4-H), 2.25–2.17 (m, 2H, 3,3-H), 2.04–1.97 (m, 2H, 2,2-H); m/z (ESI) 502.28 (100, [M−H]−); 504.31 (84, [M−H]−).
(1S,4S)-6-Bromo-1,4-bis(5-bromo-1H-indol-3-yl)-2,3,4,9-tetrahydro-1H-carbazole (4d). Yield 17%, beige powder; mp 115–117 °C; 1H NMR (DMSO-d6) δ = 11.15 (d, 3JN′/2′ = 2.3 Hz, 1H, N′-H), 11.00 (d, 3JN″/2″ = 2.4 Hz, 1H, N″-H), 10.69 (s, 1H, N-H), 7.57 (d, 4J4″/6″ = 1.9 Hz, 1H, 4″-H), 7.47 (d, 4J4′/6′ = 1.9 Hz, 1H, 4′-H), 7.36 (d, 3J7′/6′ = 8.6 Hz, 1H, 7′-H), 7.34 (d, 3J7″/6″ = 8.6 Hz, 1H, 7″-H), 7.18 (dd, 3J6′/7′ = 8.6 Hz, 4J6′/4′ = 1.9 Hz, 1H, 6′-H), 7.15 (dd, 3J6″/7″ = 8.6 Hz, 4J6″/4″ = 1.9 Hz, 1H, 6″-H), 7.15 (d, 3J8/7 = 8.5 Hz, 1H, 8-H), 7.10 (d, 3J2′/N′ = 2.3 Hz, 1H, 2′-H), 7.00 (d, 3J2″/N″ = 2.4 Hz, 1H, 2″-H), 6.99 (dd, 3J7/8 = 8.5 Hz, 4J7/5 = 2.0 Hz, 1H, 7-H), 6.89 (d, 4J5/7 = 2.0 Hz, 1H, 5-H), 4.63 (t, 3J1/2,2 = 4.9 Hz, 1H, 1-H), 4.58 (t, 3J4/3,3 = 4.9 Hz, 1H, 4-H), 2.25–2.18 (m, 2H, 3,3-H), 2.00–1.94 (m, 2H, 2,2-H); m/z (ESI) 636.18 (100, [M−H]−); 638.13 (91, [M−H]−); 634.22 (41, [M−H]−); 640.13 (32, [M−H]−).
(1S,4S)-7-Bromo-1,4-bis(5-bromo-1H-indol-3-yl)-2,3,4,9-tetrahydro-1H-carbazole (4e). Yield 12%, light pink powder; mp 149–152 °C; 1H NMR (DMSO-d6) δ = Hz, 1H, N′-H), 10.91 (d, 3JN″/2″ = 2.3 Hz, 1H, N″-H), 10.57 (s, 1H, N-H), 7.57 (d, 4J7′/5′ = 1.8 Hz, 1H, 7′-H), 7.52 (d, 4J7″/5″ = 1.8 Hz, 1H, 7″-H), 7.30 (d, 4J8/6 = 1.8 Hz, 1H, 8-H), 7.28 (d, 3J4″/5″ = 8.4 Hz, 1H, 4″-H), 7.19 (d, 3J4′/5′ = 8.4 Hz, 1H, 4′-H), 7.13 (d, 3J2′/N′ = 2.3 Hz, 1H, 2′-H), 7.03 (dd, 3J5′/4′ = 8.4 Hz, 4J5′/7′ = 1.8 Hz, 1H, 5′-H), 7.01 (d, 3J2″/N″ = 2.3 Hz, 1H, 2″-H), 6.98 (dd, 3J5″/4″ = 8.4 Hz, 4J5″/7″ = 1.8 Hz, 1H, 5″-H), 6.78 (dd, 3J6/5 = 8.4 Hz, 4J6/8 = 1.8 Hz, 1H, 6-H), 6.65 (d, 3J5/6 = 8.4 Hz, 1H, 5-H), 4.61–4.54 (m, 2H, 1-H; 4-H), 2.24–2.19 (m, 2H, 3,3-H), 2.03–1.97 (m, 2H, 2,2-H); m/z (ESI) 638.11 (100, [M−H]−); 636.13 (83, [M−H]−).
(1S,4S)-6-(Benzyloxy)-1,4-bis(5-(benzyloxy)-1H-indol-3-yl)-2,3,4,9-tetrahydro-1H-carbazole (4f). Yield 20%, brownish powder; mp 95–96 °C; 1H NMR (DMSO-d6) δ = 10.71 (d, 3JN′/2′ = 2.3 Hz, 1H, N′-H), 10.56 (d, 3JN″/2″ = 2.4 Hz, 1H, N″-H), 10.26 (s, 1H, N-H), 7.40 (dd, 3J2,6-Ph′/3,5-Ph′ = 7.9 Hz, 4J2,6-Ph′/4-Ph′ = 1.1 Hz, 2H, 2,6-Ph′-H), 7.40–7.20 (m, 13H, Ar-H), 7.25 (d, 3J7″/6″ = 8.6 Hz, 1H, 7″-H), 7.24 (d, 3J7′/6′ = 8.6 Hz, 1H, 7′-H), 7.08 (d, 3J8/7 = 8.6 Hz, 1H, 8-H), 7.06 (d, 4J4′/6′ = 2.3 Hz, 1H, 4′-H), 6.94 (d, 3J2′/N′ = 2.3 Hz, 1H, 2′-H), 6.81 (d, 3J2″/N″ = 2.4 Hz, 1H, 2″-H), 6.79 (dd, 3J6″/7″ = 8.6 Hz, 4J6″/4″ = 2.4 Hz, 1H, 6″-H), 6.77 (dd, 3J6′/7′ = 8.6 Hz, 4J6′/4′ = 2.3 Hz, 1H, 6′-H), 6.75 (d, 4J4″/6″ = 2.4 Hz, 1H, 4″-H), 6.61 (dd, 3J7/8 = 8.6 Hz, 4J7/5 = 2.5 Hz, 1H, 7-H), 6.47 (d, 4J5/7 = 2.5 Hz, 1H, 5-H), 5.01 (s, 2H, O-CH2-Ph′), 4.84 (s, 2H, O-CH2-Ph″), 4.76–4.66 (m, 2H, O-CH2-Ph), 4.52–4.45 (m, 2H, 1-H; 4-H), 2.20–2.10 (m, 2H, 3,3-H), 2.01–1.81 (m, 2H, 2,2-H); m/z (ESI) 742.33 (100, [M+Na]+); 720.26 (13, [M+H]+).
(1S,4S)-7-(Benzyloxy)-1,4-bis(5-(benzyloxy)-1H-indol-3-yl)-2,3,4,9-tetrahydro-1H-carbazole (4g). Yield 25%, light brownish powder; mp 92–93 °C; 1H NMR (DMSO-d6) δ = 10.66 (d, 3JN′/2′ = 2.3 Hz, 1H, N′-H), 10.50 (d, 3JN″/2″ = 2.3 Hz, 1H, N″-H), 10.15 (s, 1H, N-H), 7.50–7.26 (m, 15H, Ar-H), 7.27 (d, 3J4″/5″ = 8.8 Hz, 1H, 4″-H), 7.14 (d, 3J4′/5′ = 8.8 Hz, 1H, 4′-H), 6.94 (d, 4J7′/5′ = 2.3 Hz, 1H, 7′-H), 6.91 (d, 4J7″/5″ = 2.3 Hz, 1H, 7″-H), 6.88 (d, 3J2′/N′ = 2.3 Hz, 1H, 2′-H), 6.76 (d, 3J2″/N″ = 2.3 Hz, 1H, 2″-H), 6.76 (d, 4J8/6 = 2.3 Hz, 1H, 8-H), 6.68 (d, 3J5/6 = 8.6 Hz, 1H, 5-H), 6.64 (dd, 3J5′/4′ = 8.8 Hz, 4J5′/7′ = 2.3 Hz, 1H, 5′-H), 6.62 (dd, 3J5″/4″ = 8.8 Hz, 4J5″/7″ = 2.3 Hz, 1H, 5″-H), 6.41 (dd, 3J6/5 = 8.6 Hz, 4J6/8 = 2.3 Hz, 1H, 6-H), 5.10 (s, 2H, O-CH2-Ph′), 5.09 (s, 2H, O-CH2-Ph″), 4.98 (s, 2H, O-CH2-Ph), 4.47 (t, 3J1/2,2; 4/3,3 = 5.9 Hz, 2H, 1-H; 4-H), 2.21–2.15 (m, 2H, 3,3-H), 1.99–1.93 (m, 2H, 2,2-H); m/z (ESI) 742.22 (100, [M+Na]+).
3,3′-((1S,4S)-6-Cyano-2,3,4,9-tetrahydro-1H-carbazole-1,4-diyl)bis(1H-indole-5-carbonitrile) (4h). Yield 9%, white powder; mp 182–184 °C; 1H NMR (DMSO-d6) δ = 11.58 (d, 3JN′/2 = 2.3 Hz, 1H, N′-H), 11.44 (d, 3JN″/2″ = 2.4 Hz, 1H, N″-H), 11.15 (s, 1H, N-H), 7.90 (d, 4J4″/6″ = 1.5 Hz, 1H, 4″-H), 7.87 (d, 4J4′/6′ = 1.5 Hz, 1H, 4′-H), 7.57 (d, 3J7′/6′ = 8.5 Hz, 1H, 7′-H), 7.55 (d, 3J7″/6″ = 8.6 Hz, 1H, 7″-H), 7.43 (dd, 3J6′/7′ = 8.5 Hz, 4J6′/4′ = 1.5 Hz, 1H, 6′-H), 7.40 (dd, 3J6″/7″ = 8.6 Hz, 4J6″/4″ = 1.5 Hz, 1H, 6″-H), 7.34 (d, 3J8/7 = 8.4 Hz, 1H, 8-H), 7.28 (d, 3J2′/N′ = 2.3 Hz, 1H, 2′-H), 7.25 (dd, 3J7/8 = 8.4 Hz, 4J7/5 = 1.6 Hz, 1H, 7-H), 7.21 (d, 3J2″/N″ = 2.4 Hz, 1H, 2″-H), 7.12 (d, 4J5/7 = 1.6 Hz, 1H, 5-H), 4.79 (t, 3J1/2,2 = 5.2 Hz, 1H, 1-H), 4.74 (t, 3J4/3,3 = 5.2 Hz, 1H, 4-H), 2.29–2.23 (m, 2H, 3,3-H), 2.06–2.00 (m, 2H, 2,2-H); m/z (ESI) 475.23 (100, [M−H]−).
3.3. General Procedure for the Synthesis of Bisindolyl Carbazoles 5
An equimolar mixture of each compound 3 and 4 with the same indole substituent was dissolved in methanol (25 mL) and one and a half molar amount of 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) was added. The mixture was stirred at room temperature for 3 h protected from light. The reaction proceeding was followed by TLC and when no more detectable product formation was observed, the solvent was removed in vacuum. The remaining mixture was separated by column chromatography over silica gel. The eluated compound fractions were unified and the solvent was removed in vacuum to yield the solid compounds 5.
1,4-Di(1H-indol-3-yl)-9H-carbazole (5a). Yield 59%, light beige powder; mp 296–271 °C; 1H NMR (DMSO-d6) δ = 11.52 (d, 4JN′/2′ = 2.5 Hz, 1H, N′-H), 11.38 (d, 4JN″/2″ = 2.5 Hz, 1H, N″-H), 10.96 (s, 1H, N-H), 7.84 (d, 4J2′/N′ = 2.5 Hz, 1H, 2′-H), 7.75 (dbr, 3J4′/5′ = 8.0 Hz,4J4′/6′, 1H, 4′-H), 7.62 (d, 4J2″/N″ = 2.5 Hz, 1H, 2″-H), 7.61 (d, 3J2/3 = 7.5 Hz, 1H, 2-H), 7.55 (dbr, 3J7′/6′; 7″/6″ = 8.3 Hz,4J7′/5′; 7″/5″, 2H, 7′-H; 7″-H), 7.53 (dbr, 3J8/7 = 8.3 Hz,4J8/6, 1H, 8-H), 7.30 (dbr, 3J5/6 = 8.1 Hz, 4J5/7, 1H, 5-H), 7.29 (dbr, 3J4″/5″ = 8.0 Hz,4J4″/6″, 1H, 4″-H), 7.24 (ddd, 3J7/8 = 8.3 Hz, 3J7/6 = 7.1 Hz, 4J7/5 = 1.2 Hz, 1H, 7-H), 7.22 (d, 3J3/2 = 7.5 Hz, 1H, 3-H), 7.21 (ddd, 3J6′/7′ = 8.3 Hz, 3J6′/5′ =7.0 Hz, 4J6′/4′ =1.2 Hz, 1H, 6′-H), 7.18 (ddd, 3J6″/7″ = 8.3 Hz, 3J6″/5″ =6.9 Hz, 4J6″/4″ =1.2 Hz, 1H, 6″-H), 7.11 (ddd, 3J5′/4′ = 8.0 Hz, 3J5′/6′ = 7.0 Hz, 4J5′/7′ = 1.1 Hz, 1H, 5′-H), 6.97 (ddd, 3J5″/4″ = 8.0 Hz, 3J5″/6″ = 6.9 Hz, 4J5″/7″ = 1.1 Hz, 1H, 5″-H), 6.79 (ddd, 3J6/5 = 8.1 Hz, 3J6/7 = 7.1 Hz, 4J6/8 = 1.1 Hz, 1H, 6-H); m/z (ESI) 817.05 (100, [2M + Na]+); 420.26 (52, [M+Na]+).
6-Chloro-1,4-bis(5-chloro-1H-indol-3-yl)-9H-carbazole (5b). Yield 50%, yellow green powder; mp 134–137 °C; 1H NMR (DMSO-d6) δ = 11.75 (d, 3JN′/2′ = 2.5 Hz, 1H, N′-H), 11.67 (d, 3JN″/2″ = 2.5 Hz, 1H, N″-H), 11.22 (s, 1H, N-H), 7.91 (d, 3J2′/N′ = 2.5 Hz, 1H, 2′-H), 7.77 (d, 3J2″/N″ = 2.5 Hz, 1H, 2′-H), 7.66 (d, 4J4′/6′ = 2.1 Hz, 1H, 4′-H), 7.62 (d, 3J2/3 = 7.5 Hz, 1H, 2-H), 7.60 (d, 3J7″/6″ = 8.6 Hz, 1H, 7″-H), 7.57 (d, 3J7′/6′ = 8.6 Hz, 1H, 7′-H), 7.54 (d, 3J8/7 = 8.6 Hz, 1H, 8-H), 7.30 (dd, 3J7/8 = 8.6 Hz, 4J7/5 = 2.1 Hz, 1H, 7-H), 7.26 (d, 3J3/2 = 7.5 Hz, 1H, 3-H), 7.25 (d, 4J4″/6″ = 2.1 Hz, 1H, 4″-H), 7.22 (d, 4J5/7 = 2.1 Hz, 1H, 5-H), 7.22 (dd, 3J6″/7″ = 8.6 Hz, 4J6″/4″ = 2.1 Hz, 1H, 6″-H), 7.20 (dd, 3J6′/7′ = 8.6 Hz, 4J6′/4′ = 2.1 Hz, 1H, 6′-H); m/z (ESI) 498.45 (100, [M−H]−); 500.43 (95, [M−H]−); 502.44 (35, [M−H]−).
7-Chloro-1,4-bis(5-chloro-1H-indol-3-yl)-9H-carbazole (5c). Yield 26%, yellow powder; mp 168–170 °C; 1H NMR (DMSO-d6) δ = 11.68 (d, 3JN′/2′ = 2.3 Hz, 1H, N′-H), 11.56 (d, 3JN″/2″ = 2.3 Hz, 1H, N″-H), 11.13 (s, 1H, N-H), 7.86 (d, 3J2′/N′ = 2.3 Hz, 1H, 2′-H), 7.69 (d, 3J2″/N″ = 2.3 Hz, 1H, 2″-H), 7.68 (d, 3J4′/5′ = 8.2 Hz, 1H, 4′-H), 7.59 (d, 3J2/3 = 7.5 Hz, 1H, 2-H), 7.59 (d, 4J7″/5″ = 1.8 Hz, 1H, 7″-H), 7.59 (d, 4J7′/5′ = 1.9 Hz, 1H, 7′-H), 7.51 (d, 4J8/7 = 1.9 Hz, 1H, 8-H), 7.23 (d, 3J3/2 = 7.5 Hz, 1H, 3-H), 7.21 (d, 3J4″/5″ = 8.6 Hz, 1H, 4″-H), 7.18 (d, 3J5/6 = 8.5 Hz, 1H, 5-H), 7.12 (dd, 3J5′/4′ = 8.2 Hz, 4J5′/7′ = 1.9 Hz, 1H, 5′-H), 6.99 (dd, 3J5″/4″ = 8.6 Hz, 4J5″/7″ = 1.8 Hz, 1H, 5″-H), 6.86 (dd, 3J6/5 = 8.5 Hz, 4J6/8 = 1.9 Hz, 1H, 6-H); m/z (ESI) 498.54 (100, [M−H]−).
6-Bromo-1,4-bis(5-chloro-1H-indol-3-yl)-9H-carbazole (5d). Yield 51%, yellow green powder; mp 101–105 °C; 1H NMR (DMSO-d6) δ = 11.76 (d, 3JN′/2′ = 2.5 Hz, 1H, N′-H), 11.69 (d, 3JN″/2″ = 2.5 Hz, 1H, N″-H), 11.23 (s, 1H, N-H), 7.89 (d, 3J2′/N′ = 2.5 Hz, 1H, 2′-H), 7.80 (d, 4J4′/6′ = 1.9 Hz, 1H, 4′-H), 7.75 (d, 3J2″/N″ = 2.5 Hz, 1H, 2″-H), 7.62 (d, 3J2/3 = 7.5 Hz, 1H, 2-H), 7.55 (d, 3J7′/6′ = 8.5 Hz, 1H, 7′-H), 7.53 (d, 3J7″/6″ = 8.6 Hz, 1H, 7″-H), 7.50 (d, 3J8/7 = 8.5 Hz, 1H, 8-H), 7.41 (dd, 3J7/8 = 8.5 Hz, 4J7/5 = 2.0 Hz, 1H, 7-H), 7.39 (d, 4J4″/6″ = 2.0 Hz, 1H, 4″-H), 7.38 (d, 4J5/7 = 2.0 Hz, 1H, 5-H), 7.33 (dd, 3J6′/7′ = 8.5 Hz, 4J6′/4′ = 1.9 Hz, 1H, 6′-H), 7.32 (dd, 3J6″/7″ = 8.6 Hz, 4J6″/4″ = 2.0 Hz, 1H, 6″-H), 7.26 (d, 3J3/2 = 7.5 Hz, 1H, 3-H); m/z (ESI) 632.32 (100, [M−H]−); 634.27 (98, [M−H]−); 636.26 (36, [M−H]−); 630.31 (31, [M−H]−).
7-Bromo-1,4-bis(5-chloro-1H-indol-3-yl)-9H-carbazole (5e). Yield 26%, beige powder; mp 180–183 °C; 1H NMR (DMSO-d6) δ = 11.69 (d, 3JN′/2′ = 2.5 Hz, 1H, N′-H), 11.57 (d, 3JN′/2′ = 2.5 Hz, 1H, N′-H), 10.13 (s, 1H, N-H), 7.85 (d, 3J2′/N′ = 2.5 Hz, 1H, 2′-H), 7.74 (d, 4J7′/5′ = 1.8 Hz, 1H, 7′-H), 7.73 (d, 4J7″/5″ = 1.8 Hz, 1H, 7″-H), 7.68 (d, 3J2″/N″ = 2.5 Hz, 1H, 2″-H), 7.67 (d, 4J8/6 = 1.9 Hz, 1H, 8-H), 7.63 (d, 3J4′/5′ = 8.5 Hz, 1H, 4′-H), 7.60 (d, 3J2/3 = 7.5 Hz, 1H, 2-H), 7.24 (dd, 3J5′/4′ = 8.5 Hz, 4J5′/7′ = 1.8 Hz, 1H, 5′-H), 7.23 (d, 3J3/2 = 7.5 Hz, 1H, 3-H), 7.16 (d, 3J4″/5″ = 8.5 Hz, 1H, 4″-H), 7.13 (d, 3J5/6 = 8.7 Hz, 1H, 5-H), 7.10 (dd, 3J5″/4″ = 8.5 Hz, 4J5″/7″ = 1.8 Hz, 1H, 5″-H), 6.99 (dd, 3J6/5 = 8.7 Hz, 4J6/8 = 1.9 Hz, 1H, 6-H); m/z (ESI) 634.35 (100, [M−H]−); 634.47 (93, [M−H]−); 636.31 (42, [M−H]−); 630.57 (26, [M−H]−); 636.32 (12, [M−H]−).
6-(Benzyloxy)-1,4-Bis(5-(benzyloxy)-1H-indol-3-yl)-9H-carbazole (5f). Yield 24%, yellow green powder; mp 109–112 °C; 1H NMR (DMSO-d6) δ = 11.36 (d, 3JN′/2′ = 2.5 Hz, 1H, N′-H), 11.30 (d, 3JN″/2″ = 2.5 Hz, 1H, N″-H), 10.75 (s, 1H, N-H), 7.77 (d, 3J2′/N′ = 2.5 Hz, 1H, 2′-H), 7.57 (d, 3J2″/N″ = 2.5 Hz, 1H, 2″-H), 7.51 (d, 3J2/3 = 7.5 Hz, 1H, 2-H), 7.51 (d, 3J7″/6″ = 8.7 Hz, 1H, 7″-H), 7.45 (dd, 3J2,6-Ph′/3,5-Ph′ = 8.4 Hz, 4J2,6-Ph′/4-Ph′ = 1.4 Hz, 2H, 2,6-Ph′-H), 7.44 (d, 3J7′/6′ = 8.5 Hz, 1H, 7′-H), 7.43 (d, 3J8/7 = 8.7 Hz, 1H, 8-H), 7.36 (ddd, 3J3,5-Ph′/2,6-Ph′ = 8.4 Hz, 3J3,5-Ph′/4-Ph′ = 6.8 Hz, 4J3,5-Ph′/3,5-Ph′ = 1.4 Hz, 2H, 3,5-Ph′-H), 7.30 (d, 4J4′/6′ = 2.4 Hz, 1H, 4′-H), 7.30 (dd, 3J2,6-Ph″/3,5-Ph″ = 8.5 Hz, 4J2,6-Ph″/4-Ph″ = 1.4 Hz, 2H, 2,6-Ph″-H), 7.34–7.20 (m, 7H, Ar-H), 7.16 (d, 3J3/2 = 7.5 Hz, 1H, 3-H), 7.12 (dd, 3J2,6-Ph/3,5-Ph = 7.9 Hz, 4J2,6-Ph/4-Ph = 1.4 Hz, 2H, 2,6-Ph-H), 6.98 (dd, 3J6′/7′ = 8.5 Hz, 4J6′/4′ = 2.4 Hz, 1H, 6′-H), 6.96 (dd, 3J6″/7″ = 8.7 Hz, 4J6″/4″ = 2.5 Hz, 1H, 6″-H), 6.96 (d, 4J5/7 = 2.5 Hz, 1H, 5-H), 6.94 (dd, 3J7/8 = 8.7 Hz, 4J7/5 = 2.5 Hz, 1H, 7-H), 6.89 (d, 4J4″/6″ = 2.5 Hz, 1H, 4″-H), 5.09 (s, 2H, O-CH2-Ph′), 4.89 (s, 2H, O-CH2-Ph″), 4.62 (s, 2H, O-CH2-Ph); m/z (ESI) 738.54 (100, [M+Na]+).
7-(Benzyloxy)-1,4-Bis(5-(benzyloxy)-1H-indol-3-yl)-9H-carbazole (5g). Yield 33%, light brownish powder; mp 112–115 °C; 1H NMR (DMSO-d6) δ = 11.28 (d, 3JN′/2′ = 2.5 Hz, 1H, N′-H), 11.14 (d, 3JN″/2″ = 2.5 Hz, 1H, N″-H), 10.79 (s, 1H, N-H), 7.65 (d, 3J2′/N′ = 2.5 Hz, 1H, 2′-H), 7.61 (d, 3J4″/5″ = 8.7 Hz, 1H, 4″-H), 7.51 (dd, 3J2,6-Ph′/3,5-Ph′; 2,6-Ph″/3,5-Ph″ = 8.0 Hz, 4J2,6-Ph′/4-Ph′; 2,6-Ph″/4-Ph″ = 1.3 Hz, 4H, 2,6-Ph′-H; 2,6-Ph″-H), 7.48 (d, 3J2/3 = 7.5 Hz, 1H, 2-H), 7.45 (dd, 3J2,6-Ph/3,5-Ph = 8.0 Hz, 4J2,6-Ph/4-Ph = 1.4 Hz, 2H, 2,6-Ph-H), 7.44 (d, 3J2″/N″ = 2.5 Hz, 1H, 2″-H), 7.42–7.31 (m, 9H, Ar-H), 7.20 (d, 3J5/6 = 8.7 Hz, 1H, 5-H), 7.14 (d, 3J3/2 = 7.5 Hz, 1H, 3-H), 7.14 (d, 3J4′/5′ = 8.7 Hz, 1H, 4′-H), 7.11 (d, 4J8/6 = 2.3 Hz, 1H, 8-H), 7.10 (d, 4J7″/5″ = 2.4 Hz, 1H, 7″-H), 7.09 (d, 4J7′/5′ = 2.4 Hz, 1H, 7′-H), 6.85 (dd, 3J5″/4″ = 8.7 Hz, 4J5″/7″ = 2.4 Hz, 1H, 5″-H), 6.71 (dd, 3J5′/4′ = 8.7 Hz, 4J5′/7′ = 2.4 Hz, 1H, 5′-H), 6.53 (dd, 3J6/5 = 8.7 Hz, 4J6/8 = 2.3 Hz, 1H, 6-H), 5.18 (s, 2H, O-CH2-Ph′), 5.16 (s, 2H, O-CH2-Ph″), 5.10 (s, 2H, O-CH2-Ph); m/z (ESI) 738.28 (100, [M+Na]+).
3,3′-(6-Cyano-9H-carbazole-1,4-diyl)bis(1H-indole-5-carbonitrile) (5h). Yield 29%, light pink powder; mp 190–193 °C; 1H NMR (DMSO-d6) δ = 12.16 (d, 3JN′/2′ = 2.5 Hz, 1H, N′-H), 12.12 (d, 3JN″/2″ = 2.5 Hz, 1H, N″-H), 11.71 (s, 1H, N-H), 8.16 (d, 4J4′/6′ = 1.6 Hz, 1H, 4′-H), 8.05 (d, 3J2′/N′ = 2.5 Hz, 1H, 2′-H), 8.00 (d, 3J2″/N″ = 2.5 Hz, 1H, 2″-H), 7.78 (d, 3J7″/6″ = 8.4 Hz, 1H, 7″-H), 7.76 (d, 4J4″/6″ = 1.6 Hz, 1H, 4″-H), 7.75 (d, 3J2/3 = 7.5 Hz, 1H, 2-H), 7.73 (d, 3J7′/6′ = 8.5 Hz, 1H, 7′-H), 7.69 (dd, 3J7/8 = 8.5 Hz, 4J7/5 = 1.5 Hz, 1H, 7-H), 7.68 (d, 3J8/7 = 8.5 Hz, 1H, 8-H), 7.58 (dd, 3J6″/7″ = 8.4 Hz, 4J6″/4″ = 1.6 Hz, 1H, 6″-H), 7.58 (dd, 3J6′/7′ = 8.4 Hz, 4J6′/4′ = 1.6 Hz, 1H, 6′-H), 7.55 (d, 4J5/7 = 1.5 Hz, 1H, 5-H), 7.39 (d, 3J3/2 = 7.5 Hz, 1H, 3-H); m/z (ESI) 471.53 (100, [M−H]−).