## 3 Materials and Methods
#### Synthesis of the Starting Substrates
_2-(1H-Indol-3-yl)-7-methyl-1H-benzo[]imidazole_ (**3a**). A yield of 0.311 g (97%), 6 h, light-brown solid. Mp. = 156-157 \({}^{\circ}\)C (petroleum ether/EtOAc). \({}^{1}\)H NMR (400 MHz, DMSO-\(d_{6}\)) \(\delta\) = 11.86 (s, 1H), 8.44-8.40 (m, 1H), 8.30 (d, \(J\) = 2.8 Hz, 1H), 7.58-7.54 (m, 1H), 7.45 (d, \(J\) = 8.0 Hz, 1H), 7.30-7.23 (m, 2H), 7.19-7.15 (m, 1H), 7.08-7.07 (m, 1H), and 2.62 (s, 3H) ppm; \({}^{13}\)C(\({}^{1}\)H) NMR (100 MHz, DMSO-\(d_{6}\)) \(\delta\) = 147.9, 136.5, 135.9, 135.8, 128.1, 124.6, 123.6, 123.5, 123.1, 122.5, 122.5, 120.8, 120.6, 112.2, 111.2, 111.1, 103.9 (br.s), and 16.7 ppm. HRMS (ESI) calcd for C\({}_{16}\)H\({}_{14}\)N\({}_{3}\) [M+H]\({}^{+}\) 248.1182; found 248.1181. _7-Bromo-5-chloro-2-(1H-indol-3-yl)-1H-benzo[d]imidazole_ (**3a**). A yield of 0.391 g (87%), 6 h, white solid. Mp. = 115-116 \({}^{\circ}\)C (DMAC/H\({}_{2}\)O). \({}^{1}\)H NMR (400 MHz, DMSO-\(d_{6}\)) \(\delta\) = 12.84 (s, 1H), 11.70 (s, 1H), 8.52-8.51 (m, 1H), 8.19-8.18 (m, 1H), 7.53-7.50 (m, 2H), 7.41-7.40 (m, 1H), and 7.26-7.20 (m, 2H) ppm; \({}^{13}\)C(\({}^{1}\)H) NMR (100 MHz, DMSO-\(d_{6}\)) \(\delta\) = 151.3, 141.8, 136.5, 135.0, 126.9, 125.7, 125.0, 123.2, 121.2, 120.5, 111.9, 110.9, 109.7, and 105.6 ppm. HRMS (ESI) calcd for C\({}_{15}\)H\({}_{10}\)BrClN\({}_{3}\) [M+H]\({}^{+}\) 345.9741; found 345.9753. _7-Bromo-2-(1H-indol-3-yl)-5-methyl-1H-benzo[d]imidazole_ (**3 ab**). A yield of 0.343 g (81%), 6 h, light-beige solid. Mp. = 243 \({}^{\circ}\)C, decomposition (EtOH). \({}^{1}\)H NMR (400 MHz, DMSO-\(d_{6}\)) \(\delta\) = 12.34 (s, 1H), 8.58 (d, \(J\) = 2.8 Hz, 1H), 8.23-8.19 (m, 1H), 7.68-7.64 (m, 1H), 7.54 (s, 2H), 7.38-7.34 (m, 2H), and 2.50 (s, 3H) ppm; \({}^{13}\)C(\({}^{1}\)H) NMR (100 MHz, DMSO-\(d_{6}\)) \(\delta\) = 147.6, 136.5, 136.2, 133.2, 132.2, 130.2, 130.1, 128.6, 123.7, 123.3, 121.6, 119.7, 112.9, 112.4, 104.5, 99.3, and 20.7 ppm. HRMS (ESI) calcd for C\({}_{16}\)H\({}_{13}\)BrN\({}_{3}\) [M+H]\({}^{+}\) 326.0287; found 326.0278. _7-Bromo-2-(1H-indol-3-yl)-5-methoxy-1H-benzo[]imidazole_ (**3 ac**). A yield of 0.253 g (57%), 8 h, gray solid. Mp. = 118 \({}^{\circ}\)C, decomposition (petroleum ether/EtOAc). \({}^{1}\)H NMR (400 MHz, DMSO-\(d_{6}\)) \(\delta\) = 12.50 (br.s, 1H), 11.59 (s, 1H), 8.53-8.51 (m, 1H), 8.14 (br.s, 1H), 7.51-7.49 (m, 1H), 7.25-7.19 (m, 2H), 7.01-6.98 (m, 2H), and 3.83 (s, 3H) ppm; \({}^{13}\)C(\({}^{1}\)H) NMR (100 MHz, DMSO-\(d_{6}\)) \(\delta\) = 155.0, 149.5 (br.s), 136.4, 126.2 (br.s), 125.1, 122.2, 121.3, 120.2, 112.2 (br.s), 111.8, 106.2, 94.4 (br.s), and 55.9 ppm. HRMS (ESI) calcd for C\({}_{16}\)H\({}_{13}\)BrN\({}_{3}\)O [M+H]\({}^{+}\) 342.0237; found 342.0236. _5,7-Dibromo-2-(1H-indol-3-yl)-1H-benzo[d]imidazole_ (**3 ad**). A yield of 0.437 g (86%), 6 h, light-beige solid. Mp. = 148-150 \({}^{\circ}\)C (DMAC/H\({}_{2}\)O). \({}^{1}\)H NMR (400 MHz, DMSO-\(d_{6}\)) \(\delta\) = 12.82 (br.s, 1H), 11.70 (s, 1H), 8.53-8.50 (m, 1H), 8.25 (br.s, 1H), 7.68 (br.s, 1H), 7.54-7.50 (m, 2H), and 7.26-7.20 (m, 2H) ppm; \({}^{13}\)C(\({}^{1}\)H) NMR (100 MHz, DMSO-\(d_{6}\)) \(\delta\) = 151.3 (br.s), 136.4, 127.3, 127.2, 125.7, 125.1, 122.3, 121.3, 120.5, 113.1, 111.9, and 105.5 ppm. HRMS (ESI) calcd for C\({}_{15}\)H\({}_{10}\)Br\({}_{2}\)N\({}_{3}\) [M+H]\({}^{+}\) 389.9236; found 389.929. _2-(1H-Indol-3-yl)-6,7-dimethyl-1H-benzo[d]imidazole_ (**3 ae**). A yield of 0.329 g (97%), 65 h, light-beige solid. Mp. = 154-155 \({}^{\circ}\)C (EtOAc). \({}^{1}\)H NMR (400 MHz, DMSO-\(d_{6}\)) 1H), 11.53 (s, 1H), 8.58-8.56 (m, 1H), 8.18-8.17 (m, 1H), 7.51-7.49 (m, 1H), 7.27-7.24 (m, 1H), 7.23-7.18 (m, 2H), 6.96 (d, \(J\) = 8.0 Hz, 1H), 2.54 (s, 3H), and 2.35 (s, 3H) ppm; \({}^{13}\)C(\({}^{1}\)H) NMR (100 MHz, DMSO-\(d_{6}\)) \(\delta\) = 11.37, 11.69, 11.8, and 13.5 ppm. HRMS (ESI) calcd for C\({}_{17}\)H\({}_{18}\)N\({}_{3}\) [M+H]\({}^{+}\) 262.1339; found 262.1335. (CCDC 2293846 contains the supplementary crystallographic data for this paper. These data can be obtained free of charge from the Cambridge Crystallographic Data Centre via.