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Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890

(2R,5S)-5-Benzyl-2,3-di­methyl-4-oxo-2-phenyl­imidazolidin-1-ium chloride

aState Key Laboratory Breeding Base of Green Chemistry–Synthesis Technology, Zhejiang University of Technology, Hangzhou 310014, People's Republic of China, and bDepartment of Pharmaceutical and Chemical Engineering, Taizhou College, Linhai, Zhejiang 317000, People's Republic of China
*Correspondence e-mail: shuaizhang867@gmail.com

(Received 18 February 2009; accepted 21 March 2009; online 28 March 2009)

The title hydro­chloride salt, C18H21N2O+·Cl, is an imidazolidinone catalyst, which was derived from L-phenyl­alanine through cyclization with acetophenone. The imidazolidinone compound has a five-membered heterocyclic ring including two chiral centres. The imidazolidinone ring displays an envelope conformation, with the flap protonated N atom lying 0.497 (3) Å above the mean plane of the remaining four atoms. In the crystal structure, one-dimensional supra­molecular chains parallel to the crystallographic 21 screw axis are formed by N—H⋯Cl hydrogen bonds involving the NH2+ and Cl groups. Intra­molecular N—H⋯Cl inter­actions are also present.

Related literature

For chiral secondary amine catalysts based on the imidazolidinone architecture, see: Ouellet et al. (2007[Ouellet, S. G., Walji, A. B. & Macmillan, D. W. C. (2007). Acc. Chem. Res. 40, 1327-1339.]). For Michael additions of aldehydes to enones with a MacMillan imidazol­idinone catalyst, see: Hechavarria Fonseca & List (2004[Hechavarria Fonseca, M. T. & List, B. (2004). Angew. Chem. Int. Ed. 43, 3958-3960.]).

[Scheme 1]

Experimental

Crystal data
  • C18H21N2O+·Cl

  • Mr = 316.83

  • Monoclinic, P 21

  • a = 10.5797 (11) Å

  • b = 7.5876 (7) Å

  • c = 10.8741 (12) Å

  • β = 105.516 (3)°

  • V = 841.10 (15) Å3

  • Z = 2

  • Mo Kα radiation

  • μ = 0.23 mm−1

  • T = 296 K

  • 0.34 × 0.26 × 0.11 mm

Data collection
  • Rigaku R-AXIS RAPID diffractometer

  • Absorption correction: multi-scan (ABSCOR; Higashi, 1995[Higashi, T. (1995). ABSCOR. Rigaku Corporation, Tokyo, Japan.]) Tmin = 0.920, Tmax = 0.975

  • 8064 measured reflections

  • 3371 independent reflections

  • 2933 reflections with F2 > 2σ(F2)

  • Rint = 0.024

Refinement
  • R[F2 > 2σ(F2)] = 0.030

  • wR(F2) = 0.073

  • S = 1.00

  • 3371 reflections

  • 201 parameters

  • H-atom parameters constrained

  • Δρmax = 0.32 e Å−3

  • Δρmin = −0.30 e Å−3

  • Absolute structure: Flack (1983[Flack, H. D. (1983). Acta Cryst. A39, 876-881.]), 1323 Friedel pairs

  • Flack parameter: 0.03 (4)

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
N2—H201⋯Cl1 0.86 2.30 3.1170 (14) 160
N2—H202⋯Cl1i 0.86 2.24 3.0999 (14) 174
Symmetry code: (i) [-x+2, y+{\script{1\over 2}}, -z+1].

Data collection: PROCESS-AUTO (Rigaku, 1998[Rigaku (1998). PROCESS-AUTO. Rigaku Corporation, Tokyo, Japan.]); cell refinement: PROCESS-AUTO; data reduction: CrystalStructure (Rigaku/MSC, 2004[Rigaku/MSC (2004). CrystalStructure. Rigaku/MSC, The Woodlands, Texas, USA.]); program(s) used to solve structure: SIR97 (Altomare et al., 1999[Altomare, A., Burla, M. C., Camalli, M., Cascarano, G. L., Giacovazzo, C., Guagliardi, A., Moliterni, A. G. G., Polidori, G. & Spagna, R. (1999). J. Appl. Cryst. 32, 115-119.]); program(s) used to refine structure: CRYSTALS (Betteridge et al., 2003[Betteridge, P. W., Carruthers, J. R., Cooper, R. I., Prout, K. & Watkin, D. J. (2003). J. Appl. Cryst. 36, 1487.]); molecular graphics: ORTEPIII (Burnett & Johnson, 1996[Burnett, M. N. & Johnson, C. K. (1996). ORTEPIII. Report ORNL-6895. Oak Ridge National Laboratory, Tennessee, USA.]); software used to prepare material for publication: CRYSTALS.

Supporting information


Comment top

Ten years ago, MacMillan and his laboratory developed chiral secondary amine catalysts based on the imidazolidinone architecture, which has led to the development of over 30 different enantioselective transformations for asymmetric synthesis (Ouellet et al., 2007). In recent years, Michael additions of aldehydes to enones with a MacMillan imidazolidinone catalyst have been reported (Hechavarria Fonseca & List, 2004). The title compound, prepared as a kind of organocatalyst for use in the asymmetric Michael addition of aldehydes to enones, was synthesized from L-phenylalanine. The crystal structure and absolute configuration of the title compound are reported in this article.

The compound consists of an ionic pair, a protonated ammonium cation and a Cl- anion (Fig. 1). The chiral atom C1 has the expected S configuration, while the other chiral atom C3 was determined to be in a R configuration. The C1/C2/C3/N1 atoms of the imidazolidinone ring are almost coplanar. The distance of atom N2 to the C1/C2/C3/N1 mean plane is 0.497 (3) Å, while the distance of atom C12 of the benzyl group to the plane is 0.920 (4) Å. In the crystal structure of the title salt, one-dimensional supramolecular chains are formed, by intra- and inter-molecular N—H···Cl hydrogen bonds (Fig. 2).

Related literature top

For chiral secondary amine catalysts based on the imidazolidinone architecture, see: Ouellet et al. (2007). For Michael additions of aldehydes to enones with a MacMillan imidazolidinone catalyst, see: Hechavarria Fonseca & List (2004).

Experimental top

To a stirred solution of L-phenylalanine (3.87 g, 24 mmol) in dry methanol (50 ml) was added thionyl chloride (2.72 ml, 37.5 mmol). After refluxed for 48 h., the solution was concentrated under vacuum and L-phenylalanine methyl ester dichloride crystallized from methanol to give white crystals. To an ethanolic MeNH2 solution (8 M, 6 ml) was added L-phenylalanine methyl ester dihydrochloride (2.41 g, 10 mmol). The solution was stirred at room temperature for 24 h, and then the solvent removed under reduced pressure. To this residue was added MeOH (80 ml), acetophenone (3 g, 25 mmol), and a catalytic amount of p-toluenesulfonic acid (30 mg, 0.16 mmol). The resulting solution was refluxed for 24 h and further stirred at room temperature for 2 h. The mixture was subsequently concentrated under reduced pressure, giving the crude product. The resolution of the racemic compounds was by means of column chromatography with methyl and petroleum ether (1:4). The residue was taken up in ethylether and a solution of HCl-dioxane (4.0 M) was added to the precipitate. Suitable crystals were obtained by slow evaporation of a methanol solution of the crude at room temperature.

Refinement top

All H atoms were placed in calculated positions, with C—H = 0.93 (aromatic CH), 0.96 (methyl CH3), 0.97 (methylene CH2) or 0.98 Å (methine CH), and N—H = 0.86 Å. Displacement parameters for H atoms were calculated as Uiso(H) = 1.2Ueq(carrier atom).

Computing details top

Data collection: PROCESS-AUTO (Rigaku, 1998); cell refinement: PROCESS-AUTO (Rigaku, 1998); data reduction: CrystalStructure (Rigaku/MSC, 2004); program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: CRYSTALS (Betteridge et al., 2003); molecular graphics: ORTEPIII (Burnett & Johnson, 1996); software used to prepare material for publication: CRYSTALS (Betteridge et al., 2003).

Figures top
[Figure 1] Fig. 1. The asymmetric unit of the title compound, with the atomic labelling scheme. Displacement ellipsoids are drawn at the 40% probability level.
[Figure 2] Fig. 2. A part of the crystal structure of the title salt, with hydrogen bonds represented with dashed lines.
(2R,5S)-5-Benzyl-2,3-dimethyl-4-oxo-2-phenylimidazolidin-1-ium chloride top
Crystal data top
C18H21N2O+·ClF(000) = 336.00
Mr = 316.83Dx = 1.251 Mg m3
Monoclinic, P21Mo Kα radiation, λ = 0.71075 Å
Hall symbol: P 2ybCell parameters from 5642 reflections
a = 10.5797 (11) Åθ = 3.1–27.4°
b = 7.5876 (7) ŵ = 0.23 mm1
c = 10.8741 (12) ÅT = 296 K
β = 105.516 (3)°Needle, colourless
V = 841.10 (15) Å30.34 × 0.26 × 0.11 mm
Z = 2
Data collection top
Rigaku R-AXIS RAPID
diffractometer
2933 reflections with F2 > 2σ(F2)
Detector resolution: 10.00 pixels mm-1Rint = 0.024
ω scansθmax = 27.4°
Absorption correction: multi-scan
(ABSCOR; Higashi, 1995)
h = 1313
Tmin = 0.920, Tmax = 0.975k = 89
8064 measured reflectionsl = 1414
3371 independent reflections
Refinement top
Refinement on F2(Δ/σ)max < 0.001
R[F2 > 2σ(F2)] = 0.030Δρmax = 0.32 e Å3
wR(F2) = 0.073Δρmin = 0.30 e Å3
S = 1.00Extinction correction: CRYSTALS (Betteridge et al., 2003)
3371 reflectionsExtinction coefficient: 148 (16)
201 parametersAbsolute structure: Flack (1983), 1323 Friedel pairs
H-atom parameters constrainedAbsolute structure parameter: 0.03 (4)
w = 1/[0.0003Fo2 + 1.04σ(Fo2)]/(4Fo2)
Crystal data top
C18H21N2O+·ClV = 841.10 (15) Å3
Mr = 316.83Z = 2
Monoclinic, P21Mo Kα radiation
a = 10.5797 (11) ŵ = 0.23 mm1
b = 7.5876 (7) ÅT = 296 K
c = 10.8741 (12) Å0.34 × 0.26 × 0.11 mm
β = 105.516 (3)°
Data collection top
Rigaku R-AXIS RAPID
diffractometer
3371 independent reflections
Absorption correction: multi-scan
(ABSCOR; Higashi, 1995)
2933 reflections with F2 > 2σ(F2)
Tmin = 0.920, Tmax = 0.975Rint = 0.024
8064 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.030H-atom parameters constrained
wR(F2) = 0.073Δρmax = 0.32 e Å3
S = 1.00Δρmin = 0.30 e Å3
3371 reflectionsAbsolute structure: Flack (1983), 1323 Friedel pairs
201 parametersAbsolute structure parameter: 0.03 (4)
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Cl10.93865 (4)0.37096 (8)0.38333 (4)0.04566 (11)
O10.55546 (12)0.94486 (19)0.53994 (12)0.0482 (3)
N10.66144 (12)0.93555 (17)0.38197 (12)0.0328 (3)
N20.80291 (11)0.70805 (17)0.45120 (12)0.0282 (3)
C10.70374 (14)0.7044 (2)0.52767 (14)0.0300 (4)
C20.63026 (12)0.8761 (2)0.48651 (13)0.0329 (3)
C30.73966 (14)0.8101 (2)0.33039 (14)0.0299 (3)
C40.6042 (2)1.0933 (2)0.3114 (2)0.0506 (5)
C50.84477 (16)0.9014 (2)0.28214 (17)0.0433 (5)
C60.65243 (14)0.6841 (2)0.23338 (14)0.0308 (4)
C70.70586 (18)0.5811 (2)0.15399 (17)0.0424 (5)
C80.6288 (2)0.4612 (2)0.07068 (18)0.0539 (6)
C90.4987 (2)0.4414 (2)0.06476 (19)0.0538 (5)
C100.44421 (19)0.5420 (2)0.14153 (19)0.0506 (5)
C110.51948 (16)0.6636 (2)0.22594 (16)0.0395 (4)
C120.76199 (17)0.6939 (2)0.67155 (14)0.0353 (4)
C130.80340 (14)0.5137 (2)0.72774 (17)0.0347 (4)
C140.8565 (2)0.4999 (2)0.8593 (2)0.0530 (5)
C150.8969 (2)0.3397 (3)0.9158 (2)0.0684 (7)
C160.8867 (2)0.1899 (3)0.8436 (2)0.0618 (6)
C170.8346 (2)0.2009 (2)0.7136 (2)0.0582 (6)
C180.79285 (17)0.3619 (2)0.65706 (18)0.0467 (4)
H10.64380.60500.49960.036*
H70.79410.59290.15690.051*
H80.66580.39320.01820.065*
H90.44780.36020.00890.065*
H100.35570.52890.13730.061*
H110.48110.73140.27750.047*
H140.86470.60050.90970.064*
H150.93140.33321.00380.082*
H160.91480.08210.88190.074*
H170.82740.10010.66360.070*
H180.75680.36720.56920.056*
H410.54711.14960.35470.061*
H420.55491.06060.22690.061*
H430.67291.17320.30630.061*
H510.80410.97420.21030.052*
H520.89880.81450.25680.052*
H530.89800.97320.34890.052*
H1210.69690.73900.71150.042*
H1220.83880.76920.69320.042*
H2010.82130.60260.43270.034*
H2020.87340.76000.49340.034*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Cl10.0397 (2)0.0372 (2)0.0553 (2)0.0126 (2)0.00437 (17)0.0024 (2)
O10.0443 (6)0.0550 (8)0.0494 (7)0.0169 (5)0.0195 (5)0.0050 (5)
N10.0349 (6)0.0262 (6)0.0368 (7)0.0080 (5)0.0084 (5)0.0012 (5)
N20.0240 (5)0.0249 (7)0.0344 (6)0.0015 (5)0.0056 (5)0.0035 (5)
C10.0271 (7)0.0279 (8)0.0354 (8)0.0013 (6)0.0091 (6)0.0020 (6)
C20.0269 (6)0.0344 (8)0.0357 (8)0.0021 (8)0.0056 (5)0.0057 (8)
C30.0289 (7)0.0261 (8)0.0340 (8)0.0033 (6)0.0074 (6)0.0013 (6)
C40.0570 (11)0.0356 (10)0.0565 (12)0.0167 (9)0.0107 (9)0.0075 (8)
C50.0408 (8)0.0405 (11)0.0521 (10)0.0058 (8)0.0188 (8)0.0026 (8)
C60.0337 (7)0.0297 (8)0.0276 (7)0.0034 (7)0.0058 (6)0.0025 (6)
C70.0430 (9)0.0445 (10)0.0392 (9)0.0087 (8)0.0100 (8)0.0045 (8)
C80.0678 (12)0.0526 (12)0.0392 (10)0.0090 (11)0.0109 (9)0.0113 (9)
C90.0638 (12)0.0493 (11)0.0408 (10)0.0109 (10)0.0009 (9)0.0103 (8)
C100.0413 (9)0.0615 (13)0.0448 (11)0.0121 (9)0.0042 (8)0.0023 (9)
C110.0337 (8)0.0477 (11)0.0376 (9)0.0032 (8)0.0103 (7)0.0031 (8)
C120.0388 (8)0.0333 (9)0.0342 (8)0.0027 (7)0.0104 (7)0.0009 (7)
C130.0311 (8)0.0350 (9)0.0384 (9)0.0029 (7)0.0100 (7)0.0036 (7)
C140.0629 (12)0.0495 (12)0.0408 (10)0.0015 (10)0.0037 (9)0.0017 (9)
C150.0731 (13)0.0708 (19)0.0514 (12)0.0022 (13)0.0005 (10)0.0230 (12)
C160.0491 (11)0.0464 (13)0.0818 (17)0.0030 (10)0.0035 (11)0.0232 (12)
C170.0566 (11)0.0342 (11)0.0807 (15)0.0043 (9)0.0129 (11)0.0047 (10)
C180.0484 (9)0.0387 (9)0.0496 (10)0.0024 (10)0.0072 (7)0.0003 (10)
Geometric parameters (Å, º) top
O1—C21.218 (2)C17—C181.385 (2)
N1—C21.344 (2)N2—H2010.860
N1—C31.467 (2)N2—H2020.860
N1—C41.463 (2)C1—H10.980
N2—C11.503 (2)C4—H410.960
N2—C31.5176 (19)C4—H420.960
C1—C21.521 (2)C4—H430.960
C1—C121.523 (2)C5—H510.960
C3—C51.518 (2)C5—H520.960
C3—C61.536 (2)C5—H530.960
C6—C71.392 (2)C7—H70.930
C6—C111.396 (2)C8—H80.930
C7—C81.385 (2)C9—H90.930
C8—C91.368 (3)C10—H100.930
C9—C101.367 (3)C11—H110.930
C10—C111.392 (2)C12—H1210.970
C12—C131.514 (2)C12—H1220.970
C13—C141.394 (2)C14—H140.930
C13—C181.373 (2)C15—H150.930
C14—C151.378 (3)C16—H160.930
C15—C161.369 (3)C17—H170.930
C16—C171.375 (3)C18—H180.930
C2—N1—C3113.37 (13)C2—C1—H1109.3
C2—N1—C4123.90 (16)C12—C1—H1109.3
C3—N1—C4121.80 (15)N1—C4—H41109.5
C1—N2—C3106.07 (11)N1—C4—H42109.5
N2—C1—C2101.48 (12)N1—C4—H43109.5
N2—C1—C12114.76 (12)H41—C4—H42109.5
C2—C1—C12112.44 (13)H41—C4—H43109.5
O1—C2—N1126.71 (16)H42—C4—H43109.5
O1—C2—C1124.95 (15)C3—C5—H51109.5
N1—C2—C1108.34 (14)C3—C5—H52109.5
N1—C3—N299.40 (12)C3—C5—H53109.5
N1—C3—C5112.12 (13)H51—C5—H52109.5
N1—C3—C6111.70 (12)H51—C5—H53109.5
N2—C3—C5109.75 (11)H52—C5—H53109.5
N2—C3—C6108.76 (12)C6—C7—H7119.7
C5—C3—C6114.07 (14)C8—C7—H7119.7
C3—C6—C7120.44 (14)C7—C8—H8119.6
C3—C6—C11121.35 (15)C9—C8—H8119.6
C7—C6—C11118.15 (14)C8—C9—H9120.2
C6—C7—C8120.59 (18)C10—C9—H9120.2
C7—C8—C9120.8 (2)C9—C10—H10119.6
C8—C9—C10119.57 (18)C11—C10—H10119.6
C9—C10—C11120.81 (18)C6—C11—H11119.9
C6—C11—C10120.13 (17)C10—C11—H11119.9
C1—C12—C13117.13 (14)C1—C12—H121107.5
C12—C13—C14118.38 (16)C1—C12—H122107.5
C12—C13—C18124.10 (15)C13—C12—H121107.5
C14—C13—C18117.52 (17)C13—C12—H122107.5
C13—C14—C15121.02 (19)H121—C12—H122109.5
C14—C15—C16120.6 (2)C13—C14—H14119.5
C15—C16—C17119.2 (2)C15—C14—H14119.5
C16—C17—C18120.2 (2)C14—C15—H15119.7
C13—C18—C17121.50 (17)C16—C15—H15119.7
C1—N2—H201110.3C15—C16—H16120.4
C1—N2—H202110.3C17—C16—H16120.4
C3—N2—H201110.3C16—C17—H17119.9
C3—N2—H202110.3C18—C17—H17119.9
H201—N2—H202109.5C13—C18—H18119.2
N2—C1—H1109.3C17—C18—H18119.2
C2—N1—C3—N225.51 (14)N2—C3—C6—C785.03 (19)
C2—N1—C3—C5141.42 (12)N2—C3—C6—C1192.14 (17)
C2—N1—C3—C689.12 (15)C5—C3—C6—C737.8 (2)
C3—N1—C2—O1171.77 (14)C5—C3—C6—C11145.00 (16)
C3—N1—C2—C17.66 (16)C3—C6—C7—C8176.89 (16)
C4—N1—C2—O12.7 (2)C3—C6—C11—C10176.77 (16)
C4—N1—C2—C1176.74 (13)C7—C6—C11—C100.5 (2)
C4—N1—C3—N2165.15 (13)C11—C6—C7—C80.4 (2)
C4—N1—C3—C549.24 (18)C6—C7—C8—C90.0 (2)
C4—N1—C3—C680.22 (18)C7—C8—C9—C100.3 (3)
C1—N2—C3—N133.21 (13)C8—C9—C10—C110.2 (3)
C1—N2—C3—C5150.92 (13)C9—C10—C11—C60.2 (2)
C1—N2—C3—C683.66 (14)C1—C12—C13—C14179.68 (17)
C3—N2—C1—C229.59 (13)C1—C12—C13—C180.8 (2)
C3—N2—C1—C12151.10 (12)C12—C13—C14—C15179.5 (2)
N2—C1—C2—O1166.51 (14)C12—C13—C18—C17178.83 (18)
N2—C1—C2—N114.06 (14)C14—C13—C18—C170.7 (2)
N2—C1—C12—C1381.41 (18)C18—C13—C14—C150.1 (2)
C2—C1—C12—C13163.27 (14)C13—C14—C15—C160.5 (3)
C12—C1—C2—O143.4 (2)C14—C15—C16—C170.5 (3)
C12—C1—C2—N1137.17 (14)C15—C16—C17—C180.1 (2)
N1—C3—C6—C7166.27 (15)C16—C17—C18—C130.7 (3)
N1—C3—C6—C1116.6 (2)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N2—H201···Cl10.862.303.1170 (14)160
N2—H202···Cl1i0.862.243.0999 (14)174
Symmetry code: (i) x+2, y+1/2, z+1.

Experimental details

Crystal data
Chemical formulaC18H21N2O+·Cl
Mr316.83
Crystal system, space groupMonoclinic, P21
Temperature (K)296
a, b, c (Å)10.5797 (11), 7.5876 (7), 10.8741 (12)
β (°) 105.516 (3)
V3)841.10 (15)
Z2
Radiation typeMo Kα
µ (mm1)0.23
Crystal size (mm)0.34 × 0.26 × 0.11
Data collection
DiffractometerRigaku R-AXIS RAPID
diffractometer
Absorption correctionMulti-scan
(ABSCOR; Higashi, 1995)
Tmin, Tmax0.920, 0.975
No. of measured, independent and
observed [F2 > 2σ(F2)] reflections
8064, 3371, 2933
Rint0.024
(sin θ/λ)max1)0.648
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.030, 0.073, 1.00
No. of reflections3371
No. of parameters201
No. of restraints?
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.32, 0.30
Absolute structureFlack (1983), 1323 Friedel pairs
Absolute structure parameter0.03 (4)

Computer programs: PROCESS-AUTO (Rigaku, 1998), CrystalStructure (Rigaku/MSC, 2004), SIR97 (Altomare et al., 1999), CRYSTALS (Betteridge et al., 2003), ORTEPIII (Burnett & Johnson, 1996).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N2—H201···Cl10.8602.2973.1170 (14)159.5
N2—H202···Cl1i0.8602.2443.0999 (14)174.1
Symmetry code: (i) x+2, y+1/2, z+1.
 

Acknowledgements

We thank Professor Jian-Ming Gu (Zhejiang University, China), for his help.

References

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