Easy Access to Fused Tricyclic Quinoline Derivatives through Metal-Free Electrocatalytic 4 + 2 Annulation

An efficient electrocatalytic cycloaddition approach for the construction of a lactone- or lactam-fused quinoline framework is documented. Diverse arrays of functionalities are well-compatible under this metal-free, mild, and scalable electro-redox protocol. Mechanistic studies indicate an iodide-mediated electro-oxidation of secondary amines to their corresponding imines and consequent 4 + 2 cycloaddition, fabricating C–C bonds followed by rapid aromatization leading to the six-membered core structure.