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15
Representative Experimental Procedure.
A mixture of indole (0.117 g, 0.50 mmol), 4-(benzo[d]ox-azol-2-yl)benzaldehyde (0.115 g, 0.25 mmol) and [hmim]HSO4 (0.0264g, 0.50 mmol × 5% mol) in EtOH (4.0 mL) was stirred at r.t. After completion of the reaction as indicated by TLC, the mixture was concentrated in vacuo to remove the solvent. The resulting solution was extracted with Et2O (5 × 10 mL). The organic layer was dried (Na2SO4), concentrated under vacuum and purified by column chromatography to afford the pure product.
3,3′-Bis-indolyl-4-(benzo[d]oxazol-2-yl)phenylmethane (2g): pale powder; mp 234-236 °C. IR (KBr): ν = 3421, 3053 cm-1. 1H NMR (400 MHz, CDCl3): δ = 5.99 (s, 1 H), 6.72 (s, 2 H), 7.03 (dd, J
1 = 7.6 Hz, J
2 = 7.2 Hz, 2 H), 7.19 (t, J = 7.2 Hz, 2 H), 7.35 (s, 2 H), 7.40 (dd, J
1 = 7.6 Hz, J
2 = 8.0 Hz, 4 H), 7.77 (s, 1 H), 8.02 (s, 2 H), 8.18 (d, J = 8.0 Hz, 2 H). HRMS: m/z calcd for C23H20N2S: [M] 439.1685; found: 439.1666 [M+].
3,3′-Bis-(5-methyl) indolyl-3-thienylmethane (3c): pink powder; mp 217-219 °C. IR (KBr): ν = 3410, 2909, 2848 cm-1. 1H NMR (400 MHz, CDCl3): δ = 2.38 (s, 6 H), 5.90 (s, 1 H), 6.69 (s, 2 H), 6.94 (s, 1 H), 7.00-7.06 (m, 4 H), 7.24 (d, J = 5.2 Hz, 4 H), 7.83 (s, 2 H). HRMS: m/z calcd for C23H20N2S: [M] 356.1347; found: 356.1334 [M+].
