Gravar-mail: 1′-Benzyl-4,4′′-bis­(4-chloro­phen­yl)-3-(2,6-dichloro­phen­yl)-1′′-methyl-4,5-dihydro­isoxazole-5-spiro-3′-piperidine-5′-spiro-3′′-pyrrolidine-2′′-spiro-3′′′-indoline-2′′′,4′-dione