A visible-light photocatalytic N-radical cascade of hydrazones for the synthesis of dihydropyrazole-fused benzosultams

An efficient visible light photocatalytic and external oxidant-free N-radical 5-exo cyclization/addition/aromatization cascade of β,γ-unsaturated hydrazones is described, which provides a practical route to various biologically interesting dihydropyrazole-fused benzosultams in satisfactory yields.