Crystal structure of ethyl 1′,5-dimethyl-2′′,3-dioxo-3H-di­spiro­[benzo[b]thiophene-2,3′-pyrrolidine-2′,3′′-indoline]-4′-carboxyl­ate

The title compound, C(23)H(22)N(2)O(4)S, crystallized with two independent mol­ecules (A and B) in the asymmetric unit. They have very similar conformations with the pyrrolidine ring having a twisted conformation, on the C(spiro)—C(spiro) bond, in both mol­ecules. In mol­ecule A, the mean planes of the benzo­thio­phene and indoline ring systems are inclined to the mean plane of the pyrrolidine ring by 87.59 (10) and 84.51 (11)°, respectively, and to one another by 72.69 (7)°. The corresponding angles in mol­ecule B are 87.15 (10), 84.58 (10) and 72.07 (7)°, respectively. In the crystal, the A and B mol­ecules are linked to one another by two N—H⋯O hydrogen bonds, forming a dimer. These dimers are linked via C—H⋯O hydrogen bonds, forming a three-dimensional structure.