Cp. Brock et al., AN ALMOST PLANAR HYDRAZINE MOIETY IN A DIELS-ALDER ADDUCT, Acta crystallographica. Section C, Crystal structure communications, 51, 1995, pp. 2434-2437
The structure of the product of the reaction of 1,3-cyclooctadiene and
N-phenyl-1,2,4-triazoline-3,5-dione has been identified as iazatricyc
lo-[5.4.2.0(2,6)]tridec-12-ene-3,5-dione (C16H17N3O2). The distinction
between endo and exo addition cannot be made because the hydrazine mo
iety in the product molecule is almost planar.