(2E)-1-Phenyl-2-[1-(2-phenyl­prop-2-en-1-yl)pyrrolidin-2-yl­idene]ethanone

Lee G Madeley; Garreth L Morgans; Andreas Lemmerer; Joseph P Michael

doi:10.1107/S1600536812044443

. 2012 Nov 3;68(Pt 12):o3281. doi: 10.1107/S1600536812044443

(2E)-1-Phenyl-2-[1-(2-phenylprop-2-en-1-yl)pyrrolidin-2-ylidene]ethanone

Lee G Madeley ^a, Garreth L Morgans ^a, Andreas Lemmerer ^a, Joseph P Michael ^a,^*

PMCID: PMC3588828 PMID: 23468793

Abstract

The title compound, C₂₁H₂₁NO, is a vinylogous amide (enaminone) produced by reaction of 1-(2-phenylprop-2-en-1-yl)pyrrolidine-2-thione with phenacyl bromide. In the molecule, the phenyl rings are twisted from the mean plane of the pyrrolidine ring by 11.2 (1) and 67.3 (1)°. In the crystal, weak C—H⋯O hydrogen bonds link the molecules related by translation along the b axis into chains.

Related literature

For details of the synthesis of enaminones, see: Roth et al. (1971 ▶). For applications of enaminones in alkaloid synthesis, see: Michael et al. (1999 ▶). For a related enaminone structure, see: Lemmerer et al. (2007 ▶). graphic file with name e-68-o3281-scheme1.jpg

Experimental

Crystal data

C₂₁H₂₁NO
M _r = 303.39
Triclinic,
a = 5.7806 (6) Å
b = 7.9407 (7) Å
c = 9.6089 (9) Å
α = 82.579 (7)°
β = 76.793 (7)°
γ = 83.510 (7)°
V = 424.21 (7) Å³
Z = 1
Mo Kα radiation
μ = 0.07 mm⁻¹
T = 293 K
0.4 × 0.2 × 0.19 mm

Data collection

Bruker APEXII CCD area-detector diffractometer
5222 measured reflections
1563 independent reflections
970 reflections with I > 2σ(I)
R _int = 0.040

Refinement

R[F ² > 2σ(F ²)] = 0.044
wR(F ²) = 0.119
S = 0.98
1563 reflections
208 parameters
3 restraints
H-atom parameters constrained
Δρ_max = 0.11 e Å⁻³
Δρ_min = −0.13 e Å⁻³

Data collection: APEX2 (Bruker, 2005 ▶); cell refinement: SAINT-Plus (Bruker, 2004 ▶); data reduction: SAINT-Plus and XPREP (Bruker, 2004 ▶); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997 ▶) and DIAMOND (Brandenburg, 1999 ▶); software used to prepare material for publication: WinGX (Farrugia, 1999 ▶) and PLATON (Spek, 2009 ▶).

Supplementary Material

Click here for additional data file.^{(23.2KB, cif)}

Crystal structure: contains datablock(s) global, I. DOI: 10.1107/S1600536812044443/cv5350sup1.cif

e-68-o3281-sup1.cif^{(23.2KB, cif)}

Click here for additional data file.^{(75.4KB, hkl)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536812044443/cv5350Isup2.hkl

e-68-o3281-Isup2.hkl^{(75.4KB, hkl)}

Click here for additional data file.^{(2.2KB, mol)}

Supplementary material file. DOI: 10.1107/S1600536812044443/cv5350Isup3.mol

Click here for additional data file.^{(6.5KB, cml)}

Supplementary material file. DOI: 10.1107/S1600536812044443/cv5350Isup4.cml

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
C3—H3⋯O1ⁱ	0.93	2.45	3.368 (5)	170

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Symmetry code: (i) Inline graphic .

Acknowledgments

This research was supported by the University of the Witwatersrand and the Molecular Sciences Institute, which are thanked for providing the infrastructure required to do this work.

supplementary crystallographic information

Comment

The title compound, (2E)-1-phenyl-2-[1-(2-phenylprop-2-en-1-yl)pyrrolidin-2-ylidene] ethanone, (I), was prepared as part of an ongoing project dealing with the use of enaminones as intermediates for alkaloid synthesis (Michael et al., 1999).

In (I) (Fig. 1), two phenyl rings are twisted from the mean plane of the central pyrrolidine ring by 11.2 (1) and 67.3 (1)°, respectively. The (E) configuration and s-cis conformation of the exocyclic C═C bond of the enaminone are similar to those found in a related enaminone (Lemmerer et al., 2007). In the crystal, weak intermolecular C—H···O hydrogen bonds (Table 1) link the molecules related by translation along the b axis into chains (Fig. 2).

Experimental

The synthesis employed followed the Eschenmoser procedure (Roth et al., 1971). A solution of phenacyl bromide (4.30 g, 21.6 mmol) and 1-(2-phenylprop-2-en-1-yl)pyrrolidine-2-thione (4.27 g, 19.6 mmol) in dry acetonitrile (20 ml) was stirred at room temperature under an argon atmosphere until precipitation of the adduct as a gum was complete. The mixture was briefly warmed to solubilize the precipitate, after which a solution of triphenylphosphine (5.66 g, 21.6 mmol) and triethylamine (3.31 ml, 23.6 mmol) in dry MeCN (20 ml) was added dropwise to induce extrusion of sulfur, and stirring was maintained for 18 h. The solvent was evaporated and the residue was taken up into ethyl acetate (200 ml) and washed with water (3 × 100 ml) and brine (50 ml). The organic phase was dried over MgSO₄, filtered and evaporated to give an orange gum. Column chromatography on silica gel with hexane:ethyl acetate (3:2 v/v) afforded the title compound (5.42 g, 91%) as very pale yellow needles, m.p. 325—326 K.