(+)-(S,S)-1,3-Bis[(tetra­hydro­furan-2-yl)­meth­yl]thio­urea

Úlises Peña; Sylvain Bernès; René Gutiérrez

doi:10.1107/S1600536808040373

. 2008 Dec 13;65(Pt 1):o96. doi: 10.1107/S1600536808040373

(+)-(S,S)-1,3-Bis[(tetrahydrofuran-2-yl)methyl]thiourea

Úlises Peña ^a, Sylvain Bernès ^b,^*, René Gutiérrez ^a

PMCID: PMC2968003 PMID: 21581734

Abstract

The title compound, C₁₁H₂₀N₂O₂S, is an enantiomerically pure heterocycle-substituted thiourea synthesized under solvent-free conditions. The thiourea unit adopts a ZZ conformation, with the HN—(C=S)—NH core almost planar and the tetrahydrofurfuryl groups placed below and above this plane. The whole molecule thus approximates to noncrystallographic C ₂ symmetry. Unexpectedly, the C=S group is not involved in intermolecular hydrogen bonding, as generally observed in homodisubstituted thioureas. Instead, molecules form a one-dimensional network based on weak N—H⋯O(heterocycle) hydrogen bonding, resulting in a zigzag ribbon-like structure around the crystallographic 2₁ screw axis along [100].

Related literature

For general background about solvent-free synthesis, see: Tanaka & Toda (2000 ▶); Jeon et al. (2005 ▶). For C ₂ homosubstituted thioureas, see: Bailey et al. (1997 ▶); Lai & Tiekink (2002 ▶). For common hydrogen-bonding schemes in thioureas, see: Vázquez et al. (2004 ▶); Custelcean et al. (2005 ▶); Shashidhar et al. (2006 ▶); Sadiq-ur-Rehman et al. (2007 ▶); Saxena & Pike (2007 ▶).

Experimental

Crystal data

C₁₁H₂₀N₂O₂S
M _r = 244.35
Orthorhombic,
a = 7.8588 (9) Å
b = 10.8265 (11) Å
c = 15.6196 (16) Å
V = 1329.0 (2) Å³
Z = 4
Mo Kα radiation
μ = 0.23 mm⁻¹
T = 298 (1) K
0.6 × 0.6 × 0.6 mm

Data collection

Siemens P4 diffractometer
Absorption correction: ψ scan (XSCANS; Siemens, 1996 ▶) T _min = 0.782, T _max = 0.870
4611 measured reflections
3026 independent reflections
2484 reflections with I > 2σ(I)
R _int = 0.031
3 standard reflections every 97 reflections intensity decay: 1%

Refinement

R[F ² > 2σ(F ²)] = 0.054
wR(F ²) = 0.165
S = 1.03
3026 reflections
151 parameters
2 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.22 e Å⁻³
Δρ_min = −0.16 e Å⁻³
Absolute structure: Flack (1983 ▶), 1267 Friedel pairs
Flack parameter: −0.01 (14)

Data collection: XSCANS (Siemens, 1996 ▶); cell refinement: XSCANS; data reduction: XSCANS; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: Mercury (Macrae et al., 2006 ▶); software used to prepare material for publication: SHELXL97.

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536808040373/ci2734sup1.cif

e-65-00o96-sup1.cif^{(17.4KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808040373/ci2734Isup2.hkl

e-65-00o96-Isup2.hkl^{(148.6KB, hkl)}

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

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

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N2—H2⋯O18ⁱ	0.85 (1)	2.095 (17)	2.897 (3)	157 (3)
N12—H12⋯O8ⁱⁱ	0.86 (1)	2.197 (18)	2.978 (3)	150 (3)

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Symmetry codes: (i) Inline graphic ; (ii) .

Acknowledgments

Partial support from VIEP-UAP (grant No. GUPJ-NAT08-G) is acknowledged.

supplementary crystallographic information

Comment

The development of straightforward and eco-friendly synthetic procedures remains an important aim in organic synthesis. Many organic solvents, particularly chlorinated hydrocarbons, that are used in large quantities in organic reactions are potential threat to human health and environment. Thus, the design of chemical reactions under solvent-free conditions is getting a renewed interest. In this regard, solvent-free organic syntheses have great applied value and expansive prospects considering their advantages such as high efficiency and selectivity, easy separation and purification and environmental acceptability. All these merits are in accord with the green chemistry's requests of energy-saving, high efficiency and environmentally benign features (Tanaka & Toda, 2000; Jeon et al., 2005). On the other hand, N,N'-disubstituted thioureas have recently received much interest due to their diverse applications, such as, inter alia, antiviral, antituberculous, fungicidal, herbicidal activities, as well as tranquilizing and antidiabetic drugs, agrochemical properties, antioxidants in gasoline, corrosion inhibitors, etc. In view of these and in continuation of our earlier work on the synthesis of thioureas (Vázquez et al., 2004), we synthesized the title compound under solvent-free conditions (see experimental).

The asymmetric unit contains one molecule in general position (Fig. 1). As the amine used as starting material was enantiopure, the thiourea is found to be a pure (S,S) isomer. The central core HN—(C═S)—NH unit is close to be planar, the r.m.s. deviation from the mean plane S1/C1/N2/H2/N12/H12 being 0.039 Å. This core adopts a ZZ conformation (i.e. amine H atoms are arranged syn) and tetrahydrofurfuryl groups are placed below and above the central HN—(C═S)—NH plane. The whole molecule thus approximates a local C₂ point symmetry. The observed conformation is identical to that found in other related homosubstituted thioureas (Lai & Tiekink, 2002; Bailey et al., 1997).

The ZZ conformation avoids the formation of intramolecular hydrogen bonds (Saxena & Pike, 2007). Regarding the packing structure, it is clear that the thioketone functionality does not participate in intermolecular contacts. Such a situation is unexpected, since for previously X-ray characterized chiral and non-chiral homosubstituted thioureas, one-dimensional supramolecular structures based on C═S···H—N hydrogen bonds are predominant, providing that the thiourea is in a ZZ conformation (e.g. Vázquez et al., 2004; Custelcean et al., 2005; Shashidhar et al., 2006; Sadiq-ur-Rehman et al., 2007). Instead, the crystal structure of the title compound is determined by weak N—H···O(heterocycle) hydrogen bonds, aggregating molecules in a backbone arrangement (Fig. 2), parallel to the crystallographic 2₁ screw axis along [100].

Experimental

Under solvent-free conditions, (S)-(+)-tetrahydrofurfurylamine (0.49 g, 4.88 mmol) and CS₂ (0.19 g, 2.44 mmol) were mixed at 298 K, giving a white solid. The crude was recrystallized from EtOH, affording colourless crystals of the title compound. Yield 99%; m.p. 376–378 K; [α]²⁵_D=+28.7 (c=1, CHCl₃). Anal. Calcd for C₁₁H₂₀N₂O₂S: C 54.07, H 8.25, N 11.46, O 13.10, S 13.12%; found: C 53.12, H 8.18, N 11.30, O 12.98, S 13.87%. Spectroscopic data are in agreement with the X-ray formula (see archived CIF).