1,3-Diaza-6-oxabicyclo[3.1.0]hex-3-enes and their 3-oxides were obtain
ed by the photolysis of 2H-imidazole 1-oxides and 2H-imidazole 1,3-dio
xides. 1,3-Diaza-6-oxabicyclo[3.1.0]hex-3-ene 3-oxides are thermally u
nstable and are converted to the starting 2H-imidazole 1,3-dioxides; t
heir further photolysis affords a mixture of stereoisomeric 1,3-diaza-
4,7-dioxatricyclo[4.1.0.0(3,5)]heptanes.