2‐(2‐Haloalkenyl)‐aryl Halides as Substrates for Palladium‐Catalysed Tandem CN Bond Formation: Efficient Synthesis of 1‐Substituted Indoles

Abstract

Abstract 2‐(2‐Haloalkenyl)‐aryl halides, conveniently prepared in a single step from the corresponding o ‐halobenzaldehydes, are combined with amines under Pd catalysis to provide 1‐substituted indoles. All combinations of Br and Cl leaving groups can be employed, and a range of substituents on the arene, alkene and amine, can all be tolerated. The use of 1,3‐dichloro‐substituted arenes allows a third amination process to take place; these three‐component processes deliver the corresponding 4‐aminoindoles in good yields.