Organocatalytic Electrosynthesis of Cinnolines through Cascade Radical Cyclization and Migration

A straightforward one-pot two-step electrosynthesis of cinnoline derivatives from ortho-alkynyl acetophenones and sulfonyl hydrazides has been developed through the organocatalytic cascade radical cyclization and migration. This methodology features green and mild reaction conditions, good to excellent yield, broad functional group tolerance, excellent regioselectivity, and use of readily available substrates. Moreover, based on isotope labeling, radical trapping, singlet oxygen and superoxide radical anion inhibiting, cyclic voltammetry, and EPR experiments, a possible electrochemically cascade radical cyclization and migration process was proposed.