Dry reaction of indoles 1a–c with aldehydes 2a–i, ketones 2j–o and an acetal 2p on M. K10 clay at room temperature furnished 3, 3′-diindolylalkanes (DIAs: 3a–h, j–r). The novel formation of tris (3-indolyl) methane 4 from 2i through tandem reactions and of the DIAs 6 and 8 from 1d through Plancher rearrangements were also observed.