3,12-Dimesityl-6,8-dimethyl-5,10-dioxa-1,2,4,11-tetraazatricyclo[7.3.1.0^2,6]trideca-3,7,11-triene and 3,12-Dimesityl-6,8,13-trimethyl-5,10-dioxa-1,2,4,11-tetraazatricyclo[7.3.1.0^2,6]trideca-3,7,11-triene

X-ray crystallographic study of the title compounds, C₂₇H₃₂N₄O₂ and C₂₈H₃₄N₄O₂, respectively, allows us to establish the structure of the diadducts obtained from the condensation of nitrile oxides and 1,2-diazepine. The conformations of the five-, six- and seven-membered rings forming the tridecatriene are described.