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Abstract The use of halogen bonding interactions as an alternative to acid and metal catalysts for substrate activation has gained popularity in recent years. In this work we demonstrate a halogen bond assisted activation of chalcones under visible light irradiation for the Friedel‐Crafts reaction with indole to yield β ‐indolylketones. The simple and scalable protocol uses the readily available CBr 4 as halogen bond catalyst. The targets are produced in 31–94% of yield with excellent functional group tolerance. The proposed mechanism of the reaction is supported by UV‐vis, fluorescence, and NMR spectroscopic studies. Further it is demonstrated that the β ‐indolylketones can be oxidised to indole substituted α , β ‐unsaturated ketones by DDQ or cyclized to thieno2,3‐ b indoles in the presence of elemental sulfur and base.
Kumar et al. (Sat,) studied this question.