Synthesis of Densely Functionalized Pyrroles via Photoinduced C-Insertion into <i>N</i>-Alkylenamines: Sequential C(sp²)–H/C(sp³)–H Activation with Bromine Radicals

Photoinduced C_sp^₃-Br bond homolysis of ArCOCF₂Br using triethylamine as the halogen bonding (XB) acceptor was a key step for the [2 + 2 + 1] cyclization. An unprecedented strategy for assembling privileged pyrroles and their fused scaffolds via metal-, oxidant-free C-incorporation into <i>N</i>-alkylenamines through a triple-cleavage process has been disclosed. This method uses readily available alkyl amines, alkynes, or CF₃-containing <i>N</i>-benzylenamines as the starting material and features two consecutive C-C-forming reactions with ArCOCF₂Br as the carbon source. The transformation exploits the dual reactivity of bromine radicals─hydrogen-atom transfer (HAT) and reversible radical addition (RRA)─to coactivate the <i>N</i>-alkylenamines, and the resulting open-shell intermediates are then intercepted by <i>in situ</i>-generated difluoroalkyl radicals to deliver the target heterocycles.