Organocatalytic Electrosynthesis of Cinnolines through\nCascade Radical Cyclization and Migration

A straightforward\none-pot two-step electrosynthesis of cinnoline\nderivatives from <i>ortho</i>-alkynyl acetophenones and\nsulfonyl hydrazides has been developed through the organocatalytic\ncascade radical cyclization and migration. This methodology features\ngreen and mild reaction conditions, good to excellent yield, broad\nfunctional group tolerance, excellent regioselectivity, and use of\nreadily available substrates. Moreover, based on isotope labeling,\nradical trapping, singlet oxygen and superoxide radical anion inhibiting,\ncyclic voltammetry, and EPR experiments, a possible electrochemically\ncascade radical cyclization and migration process was proposed.