Low-temperature Photolysis ofortho-Substituted Azidobiphenyls. Formation of Phenazines from 2,2′-Diazidobiphenyls

It was found that the unexpected phenazines were formed as minor products by the low-temperature photolysis of 2,2′-diazidobiphenyls in a rigid matrix. The phenazine formation results from the 1,1′-C–C bond fission of the biphenyl nucleus and suggests the aziridine intermediates. The low-temperature photolysis of 2-azido-2′-methylbiphenyl and 2-azido-2′,4′,6′-trimethylbiphenyl leads to the triplet-derived phenanthridine derivatives as major products.