Tri(indolyl)phosphine oxides: Attempted formation of lower rim-capped cone conformers of calix[3]indoles

3-(p-Chlorophenyl)-4,6-dimethoxyindole (1a>), 3(p-bromophenyl)-4,6-dimethoxyindole (1b), 5-benzyloxyindole (1c), and indole (1d) yield the corresponding tri(indolyl)phosphine oxides (2a-d), on sequential treatment with n-butyllithium and phosphoryl chloride. The related phosphines, arsines, and stibines were not isolated. The stibine from indole (1a) is implicated as a reactive intermediate in the formation of the calix[3]indole (5), following its interaction with formaldehyde.