Visible‐Light Induced Selective C−H Arylation of 2‐Imino‐2H‐Chromene‐3‐Carbonitriles and Decarboxylative Ipso‐Arylation of 2‐Oxo‐2H‐Chromene‐3‐Carboxylic Acids

Visible‐light induced selective arylation of 2‐imino‐2 H ‐chromene‐3‐carbonitriles and decarboxylative ipso ‐arylation of coumarin‐3‐carboxylic acids have been accomplished under mild conditions in the absence of either base or acid and oxidant. By employing blue LEDs as an excitation source, the aryl radicals are generated by Ru(II) complex through a single‐electron transfer process, which subsequently react with 2‐imino‐2 H ‐chromene‐3‐carbonitriles and 2‐oxo‐2 H ‐chromene‐3‐carboxylic acids to produce the desired products. This is the first report on selective arylation of conjugated systems without using either an acid or a base.