(S)-2-[(2-Ammonio­phenyl)­sulfanyl­methyl]pyrrolidinium dibromide

Bailin Li; Shuai Zhang; Yifeng Wang; Shuping Luo

doi:10.1107/S1600536808021089

. 2008 Jul 19;64(Pt 8):o1549. doi: 10.1107/S1600536808021089

(S)-2-[(2-Ammoniophenyl)sulfanylmethyl]pyrrolidinium dibromide

Bailin Li ^a,^b, Shuai Zhang ^a, Yifeng Wang ^a, Shuping Luo ^a,^*

PMCID: PMC2962173 PMID: 21203253

Abstract

In the title compound, C₁₁H₁₈N₂S²⁺·2Br⁻, the pyrrolidine ring displays a half-chair conformation, with the flap C atom lying 0.522 (5) Å out of the plane of the other four atoms. The methylene C atom, which connects the pyrrolidinium ring and the thioether group, is displaced from the plane of four pyrrolidinium atoms by 0.690 (6) Å in the same direction as the flap C atom. The plane of four pyrrolidinium atoms is almost perpendicular to the benzene ring [dihedral angle = 75.02 (4)°]. The crystal structure is stabilized by hydrogen bonds between the N and Br atoms.

Related literature

The synthesis of (S)-(+)-2-bromomethylpyrrolidine hydrobromide was described by Xu et al. (2006 ▶). The development of asymmetric organocatalysis was reviewed by Seayad & List (2005 ▶).

Experimental

Crystal data

C₁₁H₁₈N₂S²⁺·2Br⁻
M _r = 370.15
Orthorhombic,
a = 7.9399 (9) Å
b = 10.8427 (13) Å
c = 17.658 (2) Å
V = 1520.2 (3) Å³
Z = 4
Mo Kα radiation
μ = 5.45 mm⁻¹
T = 293 (2) K
0.49 × 0.42 × 0.36 mm

Data collection

Bruker SMART CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ▶) T _min = 0.103, T _max = 0.137
8969 measured reflections
3311 independent reflections
1808 reflections with I > 2σ(I)
R _int = 0.136

Refinement

R[F ² > 2σ(F ²)] = 0.058
wR(F ²) = 0.134
S = 0.83
3311 reflections
158 parameters
3 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.67 e Å⁻³
Δρ_min = −0.50 e Å⁻³
Absolute structure: Flack (1983 ▶), 1394 Friedel pairs
Flack parameter: 0.00 (2)

Data collection: SMART (Bruker, 2001 ▶); cell refinement: SAINT-Plus (Bruker, 2000 ▶); data reduction: SAINT-Plus; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: SHELXTL (Sheldrick, 2008 ▶); software used to prepare material for publication: SHELXTL.

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536808021089/pk2105sup1.cif

e-64-o1549-sup1.cif^{(17.8KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808021089/pk2105Isup2.hkl

e-64-o1549-Isup2.hkl^{(162.4KB, 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—H2E⋯Br1ⁱ	0.83 (8)	2.39 (8)	3.201 (9)	169 (10)
N2—H2D⋯Br2ⁱⁱ	0.84 (6)	2.48 (4)	3.277 (9)	159 (8)
N2—H2C⋯Br1	0.84 (7)	2.47 (7)	3.298 (9)	173 (8)
N1—H1B⋯Br2	0.90	2.47	3.355 (7)	169
N1—H1A⋯Br2ⁱⁱ	0.90	2.33	3.224 (7)	170

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

supplementary crystallographic information

Comment

In recent years, the field of asymmetric organocatalysis has developed rapidly, attracting an increasing number of research groups around the world (Seayad & List, 2005). The title compound, readily synthesized from commercially available L-proline and 2-aminobenzenethiol, could act as an organocatalyst in the Michael addition of ketones to nitrostyrenes. The reaction gave the desired Michael adducts in good yields and high enantioselectivities. The structure of (S)-2-((2-ammoniophenylthio)methyl)pyrrolidinium dibromide is shown in Fig. 1.

The crystal is built of doubly protonated cations and bromide anions. The pyrrolidine ring displays a half-chair conformation, with the flap C atom lying 0.522 (5) Å from the remaining four atoms of the pyrrolidine which are almost coplanar. The methylene C atom, which connects the pyrrolidinium ring and the thioether group, is displaced from the plane of four pyrrolidinium atoms by 0.690 (6) Å in the same direction, as the flap C atom. The plane of four pyrrolidinium ring atoms is almost perpendicular to the benzene ring [dihedral angle 75.02 (4) °]. The crystal structure is stabilized by hydrogen-bonds between the N and Br atoms. The molecular packing of the title compound showing H-bridge interactions between cationic-anionic groups is shown in Fig. 2.

Experimental

The title compound was synthesized by treating 2-aminobenzenethiol (1.25 g,10 mmol) with (S)-2-bromomethylpyrrolidine hydrobromide (2.47 g,10 mmol) in MeCN (30 ml) under stirring at 353 K for 24 h (yield 87%). The compound (S)-2-bromomethylpyrrolidine hydrobromide was obtained from commercially available L-proline by reduction with NaBH₄ and subsequent bromination with PBr₃ (Xu et al., 2006). Suitable crystals of the title compound were obtained by slow evaporation of an ethanol solution at room temperature.