... 7) For a review of indole dimerization see: Smith, G. G. In Advances in Heterocyclic Chemistry; Katritzky, A ... The crude product from the organic phase was chromatographed on silica gel, eluting with a 1:3 ... 2.51 (29, 2CH3), 7.05 (m, 3H, arom), 7.18 (m, 3H, arom), 7.28 (d, J = 8.4 Hz ...