Photolysis or thermolysis of 2-azidopyridine 1-oxides (1) in benzene leads to nitrogen- elimination and ring-opening followed by recyclisation to give 6-cyano-1, 2-oxazines (5) which then usually rearrange thermally to 2-cyano-1-hydroxypyrroles (2); the photolyses provide a ready, high-yield route to 1, 2-oxazines.
