Light-induced intramolecular carbene C(sp ³ )–H insertion of <i>N</i> -tosylhydrazones; synthesis of functionalized coumarans and indolines

We report a light-induced intramolecular carbene C(sp³)-H insertion under metal-free conditions using caesium carbonate, which allows access to highly functionalized coumarans and indolines in high yields. This method's versatility is demonstrated by the bis-C-H insertion, and its synthetic applications for various transformations, one-pot synthesis, and precursors of biologically active molecules.