undergoes HAT with benzene forming xylene 9 and a new radical hybrid 20, which can attack benzene and through recombination/-hydride elimination yields biphenyl 8. However, there are multiple possibilities for the re-aromatisation of the cyclohexadienyl radicals 18/21 to product by palladium and alternative pathways should be considered, such as direct HAT by Pd I or XAT and subsequent baseassisted elimination. A light on/off experiment was also carried out, showing stepwise formation of all three products during light-on cycles, ruling out a chain reaction (Figure ).