The crystal structure of 1,7,8,9-tetrachloro-4-benzyl-10,10-dimethoxy-4-azatricyclo- （5,2,1,0^2,6）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）A, β = 92.9870（10）°, V = 3919.26（7） A3, Z = 8, Dc = 1.529 g/cm3,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.
