A Facile Synthesis of Tris(indolyl)propanes by Concerted 1,2- and 1,4-Friedel-Crafts Attack of Indoles to α,β-Unsaturated Aldimines

Abstract

The Friedel-Crafts reaction of indoles with a wide range of α,β-unsaturated aldimines catalysed by binaphthyl phosphoric acid is demonstrated. The resulting tris(indolyl)propanes are presumably generated by a concerted 1,2- and 1,4-nucleophilic attack to the conjugated imines. According to the preliminary bioassay results, the compound 4e exhibits moderate activity against pancreatic cancer cells.