Metal-Templated Asymmetric Catalysis: (Z)-1-Bromo-1-Nitrostyrenes as Versatile Substrates for Friedel-Crafts Alkylation of Indoles

An asymmetric Friedel–Crafts alkylation of indoles with (Z)-1-bromo-1-nitrostyrenes, which is efficiently catalyzed by a number of hydrogen bond interactions with the ligand sphere of bis-cyclometalated iridium complexes, has been reported. The proposed transition state exploits a hydrogen bond network, which is illustrated by the co-crystal structure of a model catalyst with an analog of the nitro substrate. The bromo functional group not only plays an important role for achieving a high asymmetric induction but also affords chiral indole-containing products, which can be readily converted to a range of useful intermediates for the creation of chiral indole building blocks.