Kristallstruktur eines überbrückten 1,2,3‐Oxadiazolidin‐5‐ons

The Crystal Structure of a Bridged 1,2,3‐Oxadiazolidin‐5‐one Derivative 3‐(2‐Allylphenyl)‐4‐phenylsydnone ( 1 ) undergoes in solution an intramolecular, 1,3‐dipolar cycloaddition reaction to give 2‐oxo‐1‐phenyl‐1,5‐methano‐1,2,4,5,6,11‐hexahydro [1,2,3] oxadiazolo [3,2‐ a ] cinnoline ( 2 ). The unique 1,2,3‐oxadiazolidin‐5‐one structure of this molecule has been proved by X‐ray analysis. The crystal structure has been solved by direct methods and refined by full‐matrix least squares calculations to R = 0,046. The crystal system is orthorhombic, space group P bca , with unit cell dimensions a = 10,546, b = 15,482, c = 16,531 Å.