Graphitic Carbon Nitride as Photocatalyst for the Direct Formylation of Anilines

The use of graphitic carbon nitride (g‐CN) for the photocatalytic radical formylation of anilines, which represents a more sustainable and attractive alternative to the currently used approaches, is reported herein. Our operationally simple method occurs under mild conditions, employing air as an oxidant. In particular, the chemistry is driven by the ability of g‐CN to reach an electronically excited state upon visible‐light absorption, which has a suitable potential energy to trigger the formation of reactive α‐amino radical species from anilines. Mechanistic investigations also proved the key role of the g‐CN to form reactive superoxide radicals from O2 via single electron transfer. Importantly, this photocatalytic transformation provides a variety of functionalized formamides (15 examples, up to 89 % yield). A new metal‐free photocatalytic approach for the direct conversion of N,N‐difunctionalized anilines into formamides derivatives (up to 89 % yield) under mild operative conditions is described herein. In this reaction, graphitic carbon nitride (g‐CN) acts as a robust and fully recyclable visible‐light photocatalyst that was easily recovered and reused up to five times without any significant drop in yield.