Electrophilic ipso-substitutions. Part 1. Reaction of 3-substituted indoles with nitronium and nitrosonium ions

Abstract

3-Substituted indoles react with nitronium and nitrosonium ions to yield 3-nitroindole. In both cases the reaction was interpreted as an electrophilic ipso-substitution. The reaction mechanism is interpreted by hypothesizing the formation of a σ-complex-like intermediate, which is some cases is preceded by an electron-transfer process. An order for the leaving abilities of the different electrofugal groups is discussed.