Dimethyl dl-2,3-dibenzyl-2,3-diisothio­cyanatosuccinate

Justyna Kalinowska-Tłuścik; Dariusz Cież; Sandrine Peyrat

doi:10.1107/S1600536812009294

. 2012 Mar 10;68(Pt 4):o1025. doi: 10.1107/S1600536812009294

Dimethyl dl-2,3-dibenzyl-2,3-diisothiocyanatosuccinate

Justyna Kalinowska-Tłuścik ^a,^*, Dariusz Cież ^a, Sandrine Peyrat ^a

PMCID: PMC3343989 PMID: 22589898

Abstract

The title compound, C₂₂H₂₀N₂O₄S₂, has approximate molecular twofold symmetry. In the crystal, the presence of C—H⋯π interactions leads to the formation of zigzag chains along [001].

Related literature

For the synthesis and spectroscopic characterization of the title compound, see: Cież (2007 ▶). For the synthesis, spectroscopic characterization and crystal structure determination of similar compounds, see: Cież et al. (2008 ▶). For diisothiocyanates, see: Morel & Marchand (2001 ▶). For C—H⋯ π and C—H⋯O interactions, see: Malone et al. (1997 ▶); Arunan et al. (2011a ▶,b ▶).

Experimental

Crystal data

C₂₂H₂₀N₂O₄S₂
M _r = 440.52
Monoclinic,
a = 9.1658 (1) Å
b = 19.3999 (4) Å
c = 12.2762 (2) Å
β = 97.891 (1)°
V = 2162.23 (6) Å³
Z = 4
Mo Kα radiation
μ = 0.28 mm⁻¹
T = 100 K
0.28 × 0.18 × 0.18 mm

Data collection

Nonius KappaCCD diffractometer
Absorption correction: multi-scan (DENZO-SMN; Otwinowski & Minor, 1997 ▶) T _min = 0.926, T _max = 0.952
9175 measured reflections
4868 independent reflections
4124 reflections with I > 2σ(I)
R _int = 0.021

Refinement

R[F ² > 2σ(F ²)] = 0.037
wR(F ²) = 0.090
S = 1.05
4868 reflections
273 parameters
H-atom parameters constrained
Δρ_max = 0.35 e Å⁻³
Δρ_min = −0.52 e Å⁻³

Data collection: COLLECT (Nonius, 1998 ▶); cell refinement: HKL SCALEPACK (Otwinowski & Minor, 1997 ▶); data reduction: HKL DENZO (Otwinowski & Minor, 1997 ▶) and SCALEPACK; program(s) used to solve structure: SIR92 (Altomare et al., 1994 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997 ▶); software used to prepare material for publication: WinGX (Farrugia, 1999 ▶), MarvinSketch (Chemaxon, 2010 ▶) and publCIF (Westrip, 2010 ▶).

Supplementary Material

Crystal structure: contains datablock(s) global, I. DOI: 10.1107/S1600536812009294/fj2516sup1.cif

e-68-o1025-sup1.cif^{(28.4KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536812009294/fj2516Isup2.hkl

e-68-o1025-Isup2.hkl^{(233.6KB, hkl)}

Supplementary material file. DOI: 10.1107/S1600536812009294/fj2516Isup3.mol

Supplementary material file. DOI: 10.1107/S1600536812009294/fj2516Isup4.cml

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

Cg is the centroid of the C32–C37 ring.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C38—H21C⋯Cgⁱ	0.98	2.61	3.461 (2)	145

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Symmetry code: (i) Inline graphic .

Acknowledgments

The authors would like to thank Professor Barbara J. Oleksyn for constructive comments and suggestions.

supplementary crystallographic information

Comment

The title compound was synthesized as a part of a larger project focusing on the synthesis of 2,3-disubstituted 2,3-diaminosuccinic acid derivatives obtained from titanium (IV) enolates of 2-isothiocyanato-carboxylates via C—C bond formation in oxidative homo-coupling of titanium (IV) enolates of 2-isothiocyanato-carboxylic esters (Cież, 2007; Cież et al., 2008). The main reason for the interest in vicinal diisothiocyanates is related to their wide application in organic syntheses (Morel & Marchand, 2001). The molecule, crystal structure of which is presented here, belongs to the rare class of organic compounds.

The overall shape of the title molecule is shown in Figure 1. There is pseudo-symmetry in the molecule (2-fold axis perpendicular to C2—C3 bond and parallel to [212]). The mutual orientation of both isothiocyanate groups, same as both benzyl groups, is gauche with dihedral angels N1—C2—C3—N2 = 73.95 (13)° and C21—C2—C3—C31 = 43.41 (16)°. The ester groups are oriented in anti conformation with dihedral angle C1—C2—C3—C4 = 158.31 (11)°.

There are two chiral centres in the molecule, localized on atoms C2 and C3, both with the same absolute configuration (R,R enantiomer shown in Figure1).

The crystal structure of the title compound is stabilized by weak interactions. The strongest are C—H···π interactions (Arunan et al., 2011a; Arunan et al., 2011b; Malone et al., 1997). They are formed between molecules related via glide plane c. The distance between hydrogen atom and centroid of the aromatic ring (Cg) is 2.611Å, with angle C38—H···Cg = 145.17°. The additionally defined angle of approach of the vector HCg to the plane of the aromatic ring, θ = 77°, and horizontal distance 0.6Å, classify this C—H···π as the second common geometry for this type of interaction observed in crystal structures (type III according to Malone et al., 1997). Intermolecular C—H···π interactions between neighbouring molecules observed in this structure form a zigzag-like chain in the [001] direction (Figure 2), where only one aromatic ring of the title molecule is involved.

Additional interaction is observed between C31—H···O4ⁱ [where (i) is x, -y + 1/2, z + 1/2] with C···O = 2.985 (2)Å, H···O = 2.612Å and angle C—H···O = 102.35°. The parameter suggests that it is not a hydrogen bond (Arunan et al., 2011a; Arunan et al., 2011b), however this interaction plays a crucial role in the stabilization of the methyl group (C38), allowing for above mentioned C—H···π. What is interesting, the sulphur atoms of the thiocyanate groups are not involved in intermolecular interactions.

The second aromatic moiety of the DL-2,3-dibenzyl-2,3-diisothiocyanato-succinic acid dimethyl ester is not involved in C—H···π. It is placed in short distance to a corresponding ring of the neighbouring molecule, related via the inversion centre (C24···C24ⁱⁱ = 3.390 (2)Å, where (ii) is -x + 2, -y, -z + 2). However, the overlapping of the aromatic rings is not observed. This suggests a hydrophobic association.

Experimental

The title compound was obtained by oxidative homo-coupling of methyl (S)-2-isothiocyanato-3-phenyl-propionate in TiCl₄/DIEA (N,N-diisopropylethylamine) system at 177 K and characterized by NMR spectroscopy (Cież, 2007). Colourless, block single crystals suitable for X-ray diffraction were obtained from ethanol solution by slow evaporation of solvent at ambient conditions.