rac-Methyl (1R,3′S)-1′,1′′-dimethyl-2,2′′-dioxo-2H-dispiro­[acenaphthyl­ene-1,2′-pyrrolidine-3′,3′′-indoline]-4′-carboxyl­ate

In the title compound, C₂₆H₂₂N₂O₄, the pyrrolidine ring adopts a twisted conformation and the other five-membered rings adopt envelope conformations with the spiro C atoms as the flap atoms. The naphthalene ring system of the dihydro­acenaphthyl­ene group forms dihedral angles of 89.2 (9) and 75.5 (6)° with the pyrrolidine and indole rings, respectively. The pyrrolidine ring makes a dihedral angle of 80.1 (9)° with the indole ring. In the crystal, mol­ecules are linked by weak C—H...O hydrogen bonds, forming chains along the b-axis direction.