The crystal structure of 1,7,8,9-tetrachloro-4-benzyl-10,10-dimethoxy-4-azatricyclo-(5,2,1,02,6)dec-8-ene-3,5-dione (C18H15Cl4NO4, Mr=451.11) has been determined by single-crystal X-ray diffraction analysis. The crystal belongs to the monoclinic system, space group P21 /c with a=18.6488(2), b=13.06430(10), c=16.1086(2) , β=92.9870(10)°, V=3919.26(7) 3 , Z=8, D c=1.529 g/cm 3 , μ=5.711 mm -1 , F(000)=1840, the final R=0.0599 and wR=0.1664 for 5645 observed reflections. The title compound is composed of a polycyclic fused pyrrolidine ring system. Three symmetric fused five-membered-ring structures were formed by the Diels-Alder reaction between N-benzylmaleimide and 5,5-dimethoxy-1,2,3,4-tetrachlorocydopentadiene.
