ortho-Selective Dearomative 2π + 2σ Photocycloadditions of Bicyclic Aza-Arenes

)-rich bicyclo2.1.1hexanes directly connected to N-heteroarenes. Photophysical experiments and DFT calculations revealed the origin of the 2π + 2σ selectivity and indicate that, in addition to the originally proposed energy transfer or direct excitation pathways, a chain reaction mechanism is operative depending on the reaction conditions.