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  1. Zukerman-Schpector J, Soto-Monsalve M, De Almeida Santos RH, Machado AHL, Correia CRD, Jotani MM, et al.
    Acta Crystallogr E Crystallogr Commun, 2018 Mar 01;74(Pt 3):414-418.
    PMID: 29765735 DOI: 10.1107/S2056989018003092
    In the title compound, C28H34N2O5, the adjacent ester and nitro-benzene substituents are connected via an intra-molecular methyl-ene-C-H⋯π(nitrobenzene) inter-action and the mol-ecule approximates to a U-shape. The di-hydro-pyrrole ring (r.m.s. deviation = 0.003 Å) is almost co-planar with the carboxyl-ate residue [Cm-N-C1-Oc (m = methine, c = carbox-yl) torsion angle = 1.8 (4)°] but is orthogonal to the 4-meth-oxy-benzene ring [dihedral angle = 84.34 (17)°]. In the crystal, methyl-ene-C-H⋯O(carbon-yl) inter-actions lead to linear supra-molecular chains along the b-axis direction, which pack without directional inter-actions between them. The analysis of the calculated Hirshfeld surface points to the importance of weak inter-atomic H⋯H, O⋯H/H⋯O and C⋯H/H⋯C contacts in the crystal.
  2. Zukerman-Schpector J, Soto-Monsalve M, De Almeida Santos RH, Garcia ALL, Correia CRD, Jotani MM, et al.
    Acta Crystallogr E Crystallogr Commun, 2018 Mar 01;74(Pt 3):371-375.
    PMID: 29765726 DOI: 10.1107/S2056989018002451
    In the title compound, C12H12N2O4, the di-hydro-pyrrole ring is almost planar (r.m.s. deviation = 0.0049 Å) and is nearly coplanar with the adjacent C2O2 residue [dihedral angle = 4.56 (9)°], which links to the 4-nitro-benzene substituent [dihedral angle = 4.58 (8)°]. The mol-ecule is concave, with the outer rings lying to the same side of the central C2O2 residue and being inclined to each other [dihedral angle = 8.30 (7)°]. In the crystal, supra-molecular layers parallel to (10-5) are sustained by nitro-benzene-C-H⋯O(carbon-yl) and pyrrole-C-H⋯O(nitro) inter-actions. The layers are connected into a three-dimensional architecture by π(pyrrole)-π(nitro-benzene) stacking [inter-centroid separation = 3.7414 (10) Å] and nitro-O⋯π(pyrrole) inter-actions.
  3. Dallasta Pedroso S, Caracelli I, Zukerman-Schpector J, Soto-Monsalve M, De Almeida Santos RH, Correia CRD, et al.
    IUCrdata, 2020 Oct;5(Pt 10):x201228.
    PMID: 36339024 DOI: 10.1107/S2414314620012286
    The title pyrrolidine compound, C18H23NO7, is a tetra-substituted species in which the five-membered ring has a twisted conformation with the twist occurring in the C-C bond bearing the adjacent acet-yloxy substituents; the Cm-Ca-Ca-Cp torsion angle is -40.76 (18)° [m = methyl-ene, a = acet-yloxy and p = phen-yl]. The N atom, which is sp 2-hybridized [sum of bond angles = 359.4°], bears an ethyl-carboxyl-ate substitutent and is connected to a methyl-ene-C atom on one side and a carbon atom bearing a 4-meth-oxy-phenyl group on the other side. Minor disorder is noted in the ethyl-carboxyl-ate substituent as well as in one of the acet-yloxy groups; the major components of the disorder have site occupancies of 0.729 (9) and 0.62 (3), respectively. The most notable feature of the mol-ecular packing is the formation of helical, supra-molecular chains aligned along the b-axis direction whereby the carbonyl-O atom not involved in a disordered residue accepts C-H⋯O inter-actions from methyl-ene-H and two-C atom separated methine-H atoms to form a six-membered {⋯HCCCH⋯O} synthon.
  4. Dallasta Pedroso S, Caracelli I, Zukerman-Schpector J, Soto-Monsalve M, De Almeida Santos RH, Correia CRD, et al.
    Acta Crystallogr E Crystallogr Commun, 2020 Jun 01;76(Pt 6):967-972.
    PMID: 32523774 DOI: 10.1107/S205698902000701X
    The title compound, C13H19NO8, is based on a tetra-substituted pyrrolidine ring, which has a twisted conformation about the central C-C bond; the Cm-Ca-Ca-Cme torsion angle is 38.26 (15)° [m = methyl-carboxyl-ate, a = acet-yloxy and me = methyl-ene]. While the N-bound ethyl-carboxyl-ate group occupies an equatorial position, the remaining substituents occupy axial positions. In the crystal, supra-molecular double-layers are formed by weak methyl- and methyl-ene-C-H⋯O(carbon-yl) inter-actions involving all four carbonyl-O atoms. The two-dimensional arrays stack along the c axis without directional inter-actions between them. The Hirshfeld surface is dominated by H⋯H (55.7%) and H⋯C/C⋯H (37.0%) contacts; H⋯H contacts are noted in the inter-double-layer region. The inter-action energy calculations point to the importance of the dispersion energy term in the stabilization of the crystal.
  5. Dallasta Pedroso S, Caracelli I, Zukerman-Schpector J, Soto-Monsalve M, De Almeida Santos RH, Correia CRD, et al.
    Acta Crystallogr E Crystallogr Commun, 2020 Jul 01;76(Pt 7):1080-1086.
    PMID: 32695456 DOI: 10.1107/S2056989020007914
    The title compound, C23H24N2O9, is a tetra-substituted pyrrolidine derivative with a twisted conformation, with the twist evident in the C-C bond bearing the adjacent acet-yloxy substituents. These are flanked on one side by a C-bound 4-meth-oxy-phen-yl group and on the other by a methyl-ene group. The almost sp 2-N atom [sum of angles = 357°] bears a 4-nitro-benzyl-oxycarbonyl substituent. In the crystal, ring-methyl-ene-C-H⋯O(acet-yloxy-carbon-yl) and methyl-ene-C-H⋯O(carbon-yl) inter-actions lead to supra-molecular layers lying parallel to (01); the layers stack without directional inter-actions between them. The analysis of the calculated Hirshfeld surfaces indicates the combined importance of H⋯H (42.3%), H⋯O/O⋯H (37.3%) and H⋯C/C⋯H (14.9%) surface contacts. Further, the inter-action energies, largely dominated by the dispersive term, point to the stabilizing influence of H⋯H and O⋯O contacts in the inter-layer region.
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