Indole β-nucleophilic substitution. Part 7. β-Halogenation of indoles. Attempted intramolecular β-nucleophilic substitution of α-arylindoles

Abstract

Intramolecular β-nucleophilic substitution of 2-aryl-1-phenylsulphonylindoles could not be achieved. N-Arylsulphonylation of 2-arylindoles with arylsulphonyl halides using phase-transfer conditions is accompanied by 3-halogenation in some cases; the proportion of 3-halogeno-arylsulphonyl-2-arylindole produced is greater with more electron rich 2-substituents supporting the view that the 3-halogenation is electrophilic in character.