Chiral anion phase transfer of aryldiazonium cations: an enantioselective synthesis of C3-diazenated pyrroloindolines

Abstract

Herein is reported the first asymmetric utilization of aryldiazonium cations as a source of electrophilic nitrogen. This is achieved through a chiral anion phase-transfer pyrroloindolinization reaction that forms C3-diazenated pyrroloindolines from simple tryptamines and aryldiazonium tetrafluoroborates. The title compounds are obtained in up to 99% yield and 96% ee. The air- and water-tolerant reaction allows electronic and steric diversity of the aryldiazonium electrophile and the tryptamine core.

Keywords: amination; asymmetric catalysis; cyclization; phase-transfer catalysis; photolysis.