Molecular iodine: An efficient catalyst for the synthesis of both symmetrical and unsymmetrical triindolylmethanes (TRIM)

Lewis acid catalyzed synthesis of triindolylmethanes from indole-3-carboxaldehyde and several other indole derivatives is described. A systematic study was carried out to evaluate the catalytic activity of seven Lewis acids and molecular iodine. Iodine appeared to be the most efficient in affording symmetrical and unsymmetrical triindolylmethanes in high yield.