TEMPO as Hydrogen Atom Transfer Catalyst in Enhancing Iminyl Radical Cyclization of O-Acetyl Oxime toward Phenanthridines and Isoquinolines

Herein, we present a strategy for promoting the cyclization of ortho-aryl or ortho alkenyl arylketone oxime ethers C-N bonds using TEMPO as a direct hydrogen atom transfer (HAT) catalyst. The reaction employs a green solvent and requires no introduction of metal additives. It only needs catalytic amount of TEMPO to drive the reaction. Gram-scale reaction yields the corresponding products with satisfactory yields, providing a novel and efficient method for the synthesis of phenanthridine and isoquinoline derivatives.