title: Crystal structures of ethyl (2S*,2'R*)-1'-methyl-2'',3-dioxo-2,3-di-hydro-dispiro-[1-benzo-thio-phene-2,3'-pyrrolidine-2',3''-indoline]-4'-carboxyl-ate and ethyl (2S*,2'R*)-5''-chloro-1'-methyl-2'',3-dioxo-2,3-di-hydro-dispiro-[1-benzo-thio-phene-2,3'-pyrrolidine-2',3''-indoline]-4'-carboxyl-ate.
abstract: In the title compounds, C22H20N2O4S, (I), and C22H19ClN2O4S, (II), the pyrrolidine rings have twist conformations on the spiro-spiro C-C bonds. In (I), the five-membered ring of the oxindole moiety has an envelope conformation with the spiro C atom as the flap, while in (II) this ring is flat (r.m.s. deviation = 0.042 Å). The mean planes of the pyrrolidine rings are inclined to the mean planes of the indole units [r.m.s deviations = 0.073 and 0.069 Å for (I) and (II), respectively] and the benzo-thio-phene ring systems (r.m.s. deviations = 0.019 and 0.034 Å for (I) and (II), respectively) by 79.57 (8) and 88.61 (7)° for (I), and by 81.99 (10) and 88.79 (10)° for (II). In both compounds, the eth-oxy-carbonyl group occupies an equatorial position with an extended conformation. The overall conformation of the two mol-ecules differs in the angle of inclination of the indole unit with respect to the benzo-thio-phene ring system, with a dihedral angle between the planes of 71.59 (5) in (I) and 82.27 (7)° in (II). In the crystal of (I), mol-ecules are linked via pairs of N-H⋯O hydrogen bonds, forming inversion dimers enclosing R 2 (2)(14) loops. The dimers are linked via C-H⋯O and bifurcated C-H⋯O(O) hydrogen bonds, forming sheets lying parallel to (100). In the crystal of (II), mol-ecules are again linked via pairs of N-H⋯O hydrogen bonds, forming inversion dimers but enclosing smaller R 2 (2)(8) loops. Here, the dimers are linked by C-H⋯O hydrogen bonds, forming ribbons propagating along [010].
authors.affiliation: Department of Physics, Queen Mary's College (Autonomous), Chennai 600 004, India.
authors.forename: M P
authors.initials: MP
authors.lastname: Savithri
authors.affiliation: Department of Organic Chemistry, University of Madras, Guindy Campus, Chennai 600 025, India.
authors.forename: M
authors.initials: M
authors.lastname: Suresh
authors.affiliation: Department of Organic Chemistry, University of Madras, Guindy Campus, Chennai 600 025, India.
authors.forename: R
authors.initials: R
authors.lastname: Raghunathan
authors.affiliation: Department of Physics, Presidency College (Autonomous), Chennai 600 005, India.
authors.forename: G
authors.initials: G
authors.lastname: Vimala
authors.affiliation: Department of Physics, Presidency College (Autonomous), Chennai 600 005, India.
authors.forename: R
authors.initials: R
authors.lastname: Raja
authors.affiliation: Department of Physics, Presidency College (Autonomous), Chennai 600 005, India.
authors.forename: A
authors.initials: A
authors.lastname: SubbiahPandi
keywords: benzo­thio­phene; crystal structure; di­spiro; pyrrolidine-indole