Formation of C-amido-calix[3]indoles from 2'- and 7'-indolylglyoxylamides

Article abstract of DOI:10.1016/S0040-4020(00)00774-2

A range of 2'- and 7'-indolylglyoxylic amides 1 and 2, derived from 3-(4'-chlorophenyl)-4,6-dimethoxyindole, have been reduced to the corresponding alcohols 3 and 4 respectively. On treatment with acid, these alcohols underwent trimerisation to give the calix[3]indoles 8. The major conformer was generally the flattened partial cone, but in certain cases the cone conformers could be detected and even isolated. The related 2'-indolylglyoxylic amides 13, derived from 4,6-dimethoxy-3-methylindole, were also converted into calix[3]indoles 15. (C) 2000 Elsevier Science Ltd.