Email Post: 5′′-(4-Chloro­benzyl­idene)-1′-(4-chloro­phen­yl)-1′′-methyl-1′,2′,3′,5′,6′,7′,8′,8a’-octa­hydro­dispiro­[acenaphthyl­ene-1,3′-indolizine-2′,3′′-piperidine]-2,4′′(1H)-dione