Synthesis of cyclohexylidenehydrazine-fused polycyclics via a photocatalytic radical cascade reaction of 2-ethynylaldehyde hydrazones.

A general and efficient visible-light photoredox-catalyzed cascade annulation of 2-ethynylaldehyde hydrazones with α-bromo-carbonyls for the synthesis of various cyclohexylidene-hydrazine-fused polycyclic compounds is described. This protocol is characterized by a broad substrate scope, mild conditions and amenability to gram-scale synthesis.