organic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890

2-(4-Meth­­oxy­phenyl)-2-oxoethan­aminium chloride

aX-ray Crystallography Unit, School of Physics, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia, bDepartment of Pharmaceutical Chemistry, College of Pharmacy, King Saud University, PO Box 2457, Riyadh 11451, Saudi Arabia, and cDepartment of Chemistry, Mangalore University, Karnataka, India
*Correspondence e-mail: hkfun@usm.my

(Received 12 September 2012; accepted 18 September 2012; online 22 September 2012)

In the cation of the title compound, C9H12NO2+·Cl, the dihedral angle between the 2-oxoethanaminium N—C—C(=O)– plane [maximum deviation = 0.0148 (12) Å] and the benzene ring is 7.98 (8)°. The meth­oxy group is approximately in-plane with the benzene ring, with a C—O—C—C torsion angle of −2.91 (18)°. In the crystal, the cations and chloride anions are connected by N—H⋯Cl and C—H⋯Cl hydrogen bonds, forming a layer parallel to the bc plane. A C—H⋯π inter­action further links the layers.

Related literature

For syntheses and applications of nitro­gen-containing heterocyclic compounds, see: Alvarez-Builla et al. (2011[Alvarez-Builla, J., Vaquero, J. J. & Barluenga, J. (2011). Editors. Modern Heterocyclic Chemistry, Vol. 2, pp. 635-1047. Weinheim: Wiley-VCH.]); Katritzky et al. (2010[Katritzky, A. R., Ramsden, C. A., Joule, J. A. & Zhdankin, V. V. (2010). Handbook of Heterocyclic Chemistry, 3rd ed. Oxford: Elsevier.]); Chen et al. (2011[Chen, S. B., Tan, J. H., Ou, T. M., Huang, S. L., An, L. K., Luo, H. B., Li, D., Gu, L. Q. & Huang, Z. S. (2011). Bioorg. Med. Chem. Lett. 21, 1004-1009.]). For a related structure, see: Zhang et al. (2009[Zhang, J., Zhuang, L. & Wang, G. (2009). Acta Cryst. E65, o2245.]). For the stability of the temperature controller used for the data collection, see: Cosier & Glazer (1986[Cosier, J. & Glazer, A. M. (1986). J. Appl. Cryst. 19, 105-107.]).

[Scheme 1]

Experimental

Crystal data
  • C9H12NO2+·Cl

  • Mr = 201.65

  • Monoclinic, P 21 /c

  • a = 12.2822 (8) Å

  • b = 7.1605 (4) Å

  • c = 11.1226 (7) Å

  • β = 92.435 (1)°

  • V = 977.31 (10) Å3

  • Z = 4

  • Mo Kα radiation

  • μ = 0.36 mm−1

  • T = 100 K

  • 0.40 × 0.24 × 0.17 mm

Data collection
  • Bruker SMART APEXII DUO CCD area-detector diffractometer

  • Absorption correction: multi-scan (SADABS; Bruker, 2009[Bruker (2009). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]) Tmin = 0.870, Tmax = 0.942

  • 10764 measured reflections

  • 2871 independent reflections

  • 2622 reflections with I > 2σ(I)

  • Rint = 0.019

Refinement
  • R[F2 > 2σ(F2)] = 0.035

  • wR(F2) = 0.099

  • S = 1.08

  • 2871 reflections

  • 132 parameters

  • H atoms treated by a mixture of independent and constrained refinement

  • Δρmax = 0.66 e Å−3

  • Δρmin = −0.31 e Å−3

Table 1
Hydrogen-bond geometry (Å, °)

Cg1 is the centroid of the C2–C7 ring.

D—H⋯A D—H H⋯A DA D—H⋯A
N1—H2N1⋯Cl1i 0.95 (2) 2.26 (2) 3.2061 (14) 173.6 (15)
N1—H3N1⋯Cl1 0.99 (2) 2.19 (2) 3.1496 (12) 162.6 (19)
N1—H1N1⋯Cl1ii 0.97 (2) 2.27 (2) 3.2240 (12) 168.4 (19)
C9—H9B⋯Cl1iii 0.99 2.69 3.6135 (13) 156
C3—H3ACg1iv 0.95 2.53 3.3909 (14) 150
Symmetry codes: (i) [-x+2, y-{\script{1\over 2}}, -z+{\script{3\over 2}}]; (ii) [x, -y+{\script{1\over 2}}, z+{\script{1\over 2}}]; (iii) [-x+2, y+{\script{1\over 2}}, -z+{\script{3\over 2}}]; (iv) [-x+1, y+{\script{1\over 2}}, -z+{\script{3\over 2}}].

Data collection: APEX2 (Bruker, 2009[Bruker (2009). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: SAINT (Bruker, 2009[Bruker (2009). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2009[Spek, A. L. (2009). Acta Cryst. D65, 148-155.]).

Supporting information


Comment top

The synthesis of nitrogen-containing heterocycles has long been a topic of intense research (Alvarez-Builla et al., 2011; Katritzky et al., 2010). This is due, in large part, to the importance of these compounds as drug candidates. The vast majority of new molecular entities (NMEs) contain at least one nitrogen atom in the chemical structure. A subcategory of these compounds are imidazoles, which are notable pharmacophores in a number of areas of discovery chemistry research (Chen et al., 2011). Appropriately, numerous synthetic approaches to these compounds have been published in the literature (Alvarez-Builla et al., 2011). Phenacyl amines are the key intermediate in the synthesis of various ketoamides and also provides a robust synthetic route toward 1H-4-substituted imidazole developed using phenacyl amines. Herein we report the synthesis and crystal structure of 2-(4-methoxyphenyl)-2-oxoethanaminium chloride.

The asymmetric unit of the title compound as shown in Fig. 1 consists of one 2-(4-methoxyphenyl)-2-oxoethanaminium cation and one chloride anion. One proton is transferred from the hydrochloric acid to the N atom. The ketone side chain and the methoxy group are coplanar with the benzene ring (C2–C7) with the torsion angles of C6—C5—C8—C9 = 173.82 (11)° and C1—O1—C2—C7 = -2.91 (18)°, respectively. The bond lengths and angles are similar to a related structure (Zhang et al., 2009).

The crystal structure (Fig. 2) is mainly stabilized by N—H···Cl and C—H···Cl hydrogen bonds (Table 1). In the crystal structure, the amine N atom acts as donor whereas the chloride anion acts as acceptor, linking them into a layer parallel to the bc plane. A C—H···π interaction (Table 1), involving the benzene ring, further consolidates the crystal structure.

Related literature top

For syntheses and applications of nitrogen-containing heterocyclic compounds, see: Alvarez-Builla et al. (2011); Katritzky et al. (2010); Chen et al. (2011). For a related structure, see: Zhang et al. (2009). For the stability of the temperature controller used for the data collection, see: Cosier & Glazer (1986).

Experimental top

A 40 ml ethanolic solution of 5 mmol 4-methoxy phenacyl bromide was stirred with 5 mmol of HMTA for 10 h. The solid precipitated was filtered and the precipitate was dissolved in HCl and evaporated to dryness to get the crystals. M.p.: 433 K.

Refinement top

N-bound H atoms were located in a difference Fourier map and were refined freely [N—H = 0.95 (2) to 0.98 (2) Å]. The remaining H atoms were positioned geometrically (C—H = 0.95 to 0.99 Å) and refined with a riding model with Uiso(H) = 1.2 or 1.5 Ueq(C). A rotating group model was applied to the methyl group. In the final refinement, one outliner, 1 0 0, was omitted.

Structure description top

The synthesis of nitrogen-containing heterocycles has long been a topic of intense research (Alvarez-Builla et al., 2011; Katritzky et al., 2010). This is due, in large part, to the importance of these compounds as drug candidates. The vast majority of new molecular entities (NMEs) contain at least one nitrogen atom in the chemical structure. A subcategory of these compounds are imidazoles, which are notable pharmacophores in a number of areas of discovery chemistry research (Chen et al., 2011). Appropriately, numerous synthetic approaches to these compounds have been published in the literature (Alvarez-Builla et al., 2011). Phenacyl amines are the key intermediate in the synthesis of various ketoamides and also provides a robust synthetic route toward 1H-4-substituted imidazole developed using phenacyl amines. Herein we report the synthesis and crystal structure of 2-(4-methoxyphenyl)-2-oxoethanaminium chloride.

The asymmetric unit of the title compound as shown in Fig. 1 consists of one 2-(4-methoxyphenyl)-2-oxoethanaminium cation and one chloride anion. One proton is transferred from the hydrochloric acid to the N atom. The ketone side chain and the methoxy group are coplanar with the benzene ring (C2–C7) with the torsion angles of C6—C5—C8—C9 = 173.82 (11)° and C1—O1—C2—C7 = -2.91 (18)°, respectively. The bond lengths and angles are similar to a related structure (Zhang et al., 2009).

The crystal structure (Fig. 2) is mainly stabilized by N—H···Cl and C—H···Cl hydrogen bonds (Table 1). In the crystal structure, the amine N atom acts as donor whereas the chloride anion acts as acceptor, linking them into a layer parallel to the bc plane. A C—H···π interaction (Table 1), involving the benzene ring, further consolidates the crystal structure.

For syntheses and applications of nitrogen-containing heterocyclic compounds, see: Alvarez-Builla et al. (2011); Katritzky et al. (2010); Chen et al. (2011). For a related structure, see: Zhang et al. (2009). For the stability of the temperature controller used for the data collection, see: Cosier & Glazer (1986).

Computing details top

Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT (Bruker, 2009); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2009).

Figures top
[Figure 1] Fig. 1. The molecular structure of the title compound, showing 50% probability displacement ellipsoids.
[Figure 2] Fig. 2. The crystal packing of the title compound, viewed along the a axis, showing the layer parallel to the bc plane. H atoms not involved in the intermolecular interactions (dashed lines) have been omitted for clarity.
2-(4-Methoxyphenyl)-2-oxoethanaminium chloride top
Crystal data top
C9H12NO2+·ClF(000) = 424
Mr = 201.65Dx = 1.370 Mg m3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybcCell parameters from 6587 reflections
a = 12.2822 (8) Åθ = 3.3–30.1°
b = 7.1605 (4) ŵ = 0.36 mm1
c = 11.1226 (7) ÅT = 100 K
β = 92.435 (1)°Block, yellow
V = 977.31 (10) Å30.40 × 0.24 × 0.17 mm
Z = 4
Data collection top
Bruker SMART APEXII DUO CCD area-detector
diffractometer
2871 independent reflections
Radiation source: fine-focus sealed tube2622 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.019
φ and ω scansθmax = 30.2°, θmin = 3.3°
Absorption correction: multi-scan
(SADABS; Bruker, 2009)
h = 1717
Tmin = 0.870, Tmax = 0.942k = 1010
10764 measured reflectionsl = 1515
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.035H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.099 w = 1/[σ2(Fo2) + (0.0509P)2 + 0.5579P]
where P = (Fo2 + 2Fc2)/3
S = 1.08(Δ/σ)max = 0.001
2871 reflectionsΔρmax = 0.66 e Å3
132 parametersΔρmin = 0.31 e Å3
0 restraintsExtinction correction: SHELXTL (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.027 (3)
Crystal data top
C9H12NO2+·ClV = 977.31 (10) Å3
Mr = 201.65Z = 4
Monoclinic, P21/cMo Kα radiation
a = 12.2822 (8) ŵ = 0.36 mm1
b = 7.1605 (4) ÅT = 100 K
c = 11.1226 (7) Å0.40 × 0.24 × 0.17 mm
β = 92.435 (1)°
Data collection top
Bruker SMART APEXII DUO CCD area-detector
diffractometer
2871 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 2009)
2622 reflections with I > 2σ(I)
Tmin = 0.870, Tmax = 0.942Rint = 0.019
10764 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0350 restraints
wR(F2) = 0.099H atoms treated by a mixture of independent and constrained refinement
S = 1.08Δρmax = 0.66 e Å3
2871 reflectionsΔρmin = 0.31 e Å3
132 parameters
Special details top

Experimental. The crystal was placed in the cold stream of an Oxford Cryosystems Cobra open-flow nitrogen cryostat (Cosier & Glazer, 1986) operating at 100.0 (1) K.

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
O10.31506 (8)0.43288 (14)0.83094 (9)0.0240 (2)
O20.77620 (8)0.12046 (16)1.02231 (9)0.0271 (2)
N10.93861 (9)0.16996 (19)0.87460 (10)0.0224 (2)
C10.22952 (11)0.3669 (2)0.90447 (13)0.0252 (3)
H1A0.16010.42270.87670.038*
H1B0.24570.40230.98840.038*
H1C0.22450.23060.89840.038*
C20.41825 (10)0.37782 (18)0.86212 (11)0.0187 (2)
C30.49898 (10)0.43820 (18)0.78563 (11)0.0198 (2)
H3A0.47950.51370.71790.024*
C40.60660 (10)0.38863 (18)0.80810 (11)0.0191 (2)
H4A0.66070.42970.75550.023*
C50.63640 (10)0.27779 (17)0.90828 (11)0.0176 (2)
C60.55558 (10)0.22213 (17)0.98526 (11)0.0186 (2)
H6A0.57540.15041.05460.022*
C70.44689 (11)0.26912 (17)0.96292 (11)0.0192 (2)
H7A0.39280.22801.01540.023*
C80.74917 (10)0.21092 (17)0.93292 (11)0.0189 (2)
C90.83234 (11)0.25722 (18)0.84067 (11)0.0202 (2)
H9A0.80640.21110.76060.024*
H9B0.84120.39440.83550.024*
Cl11.05551 (2)0.22239 (4)0.63026 (2)0.01705 (10)
H1N10.9649 (18)0.215 (3)0.952 (2)0.041 (6)*
H2N10.9365 (14)0.037 (3)0.8780 (16)0.029 (5)*
H3N10.9882 (18)0.196 (3)0.810 (2)0.040 (6)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O10.0205 (4)0.0274 (5)0.0244 (4)0.0012 (4)0.0030 (3)0.0044 (4)
O20.0252 (5)0.0328 (5)0.0232 (5)0.0012 (4)0.0017 (4)0.0083 (4)
N10.0209 (5)0.0255 (6)0.0210 (5)0.0000 (4)0.0023 (4)0.0003 (4)
C10.0207 (6)0.0270 (7)0.0281 (6)0.0017 (5)0.0041 (5)0.0015 (5)
C20.0211 (5)0.0171 (5)0.0180 (5)0.0001 (4)0.0018 (4)0.0018 (4)
C30.0242 (6)0.0186 (6)0.0166 (5)0.0008 (4)0.0026 (4)0.0019 (4)
C40.0231 (6)0.0184 (5)0.0161 (5)0.0016 (4)0.0040 (4)0.0010 (4)
C50.0200 (5)0.0171 (5)0.0157 (5)0.0016 (4)0.0015 (4)0.0010 (4)
C60.0235 (6)0.0175 (5)0.0150 (5)0.0013 (4)0.0018 (4)0.0004 (4)
C70.0223 (6)0.0189 (6)0.0168 (5)0.0021 (4)0.0043 (4)0.0002 (4)
C80.0215 (5)0.0178 (5)0.0176 (5)0.0022 (4)0.0018 (4)0.0005 (4)
C90.0209 (6)0.0209 (6)0.0189 (5)0.0001 (4)0.0028 (4)0.0010 (4)
Cl10.02011 (15)0.01794 (16)0.01333 (15)0.00302 (9)0.00337 (9)0.00102 (9)
Geometric parameters (Å, º) top
O1—C21.3582 (15)C3—C41.3812 (17)
O1—C11.4384 (16)C3—H3A0.9500
O2—C81.2208 (16)C4—C51.4039 (17)
N1—C91.4814 (17)C4—H4A0.9500
N1—H1N10.96 (2)C5—C61.3962 (17)
N1—H2N10.95 (2)C5—C81.4800 (17)
N1—H3N10.98 (2)C6—C71.3888 (18)
C1—H1A0.9800C6—H6A0.9500
C1—H1B0.9800C7—H7A0.9500
C1—H1C0.9800C8—C91.5150 (18)
C2—C71.3975 (17)C9—H9A0.9900
C2—C31.4020 (17)C9—H9B0.9900
C2—O1—C1117.11 (10)C3—C4—H4A119.9
C9—N1—H1N1110.3 (13)C5—C4—H4A119.9
C9—N1—H2N1114.0 (11)C6—C5—C4118.68 (11)
H1N1—N1—H2N1107.7 (16)C6—C5—C8118.57 (11)
C9—N1—H3N1107.4 (13)C4—C5—C8122.70 (11)
H1N1—N1—H3N1113.7 (19)C7—C6—C5121.61 (11)
H2N1—N1—H3N1103.8 (17)C7—C6—H6A119.2
O1—C1—H1A109.5C5—C6—H6A119.2
O1—C1—H1B109.5C6—C7—C2119.06 (11)
H1A—C1—H1B109.5C6—C7—H7A120.5
O1—C1—H1C109.5C2—C7—H7A120.5
H1A—C1—H1C109.5O2—C8—C5122.85 (11)
H1B—C1—H1C109.5O2—C8—C9119.99 (12)
O1—C2—C7124.53 (11)C5—C8—C9117.16 (10)
O1—C2—C3115.59 (11)N1—C9—C8110.32 (10)
C7—C2—C3119.88 (12)N1—C9—H9A109.6
C4—C3—C2120.47 (11)C8—C9—H9A109.6
C4—C3—H3A119.8N1—C9—H9B109.6
C2—C3—H3A119.8C8—C9—H9B109.6
C3—C4—C5120.27 (11)H9A—C9—H9B108.1
C1—O1—C2—C72.91 (18)C5—C6—C7—C21.25 (19)
C1—O1—C2—C3177.42 (11)O1—C2—C7—C6179.90 (12)
O1—C2—C3—C4179.30 (11)C3—C2—C7—C60.23 (18)
C7—C2—C3—C41.01 (19)C6—C5—C8—O25.45 (19)
C2—C3—C4—C50.31 (19)C4—C5—C8—O2177.16 (12)
C3—C4—C5—C61.13 (18)C6—C5—C8—C9173.82 (11)
C3—C4—C5—C8176.25 (11)C4—C5—C8—C93.57 (17)
C4—C5—C6—C71.93 (19)O2—C8—C9—N13.06 (17)
C8—C5—C6—C7175.56 (11)C5—C8—C9—N1176.23 (11)
Hydrogen-bond geometry (Å, º) top
Cg1 is the centroid of the C2–C7 ring.
D—H···AD—HH···AD···AD—H···A
N1—H2N1···Cl1i0.95 (2)2.26 (2)3.2061 (14)173.6 (15)
N1—H3N1···Cl10.99 (2)2.19 (2)3.1496 (12)162.6 (19)
N1—H1N1···Cl1ii0.97 (2)2.27 (2)3.2240 (12)168.4 (19)
C9—H9B···Cl1iii0.992.693.6135 (13)156
C3—H3A···Cg1iv0.952.533.3909 (14)150
Symmetry codes: (i) x+2, y1/2, z+3/2; (ii) x, y+1/2, z+1/2; (iii) x+2, y+1/2, z+3/2; (iv) x+1, y+1/2, z+3/2.

Experimental details

Crystal data
Chemical formulaC9H12NO2+·Cl
Mr201.65
Crystal system, space groupMonoclinic, P21/c
Temperature (K)100
a, b, c (Å)12.2822 (8), 7.1605 (4), 11.1226 (7)
β (°) 92.435 (1)
V3)977.31 (10)
Z4
Radiation typeMo Kα
µ (mm1)0.36
Crystal size (mm)0.40 × 0.24 × 0.17
Data collection
DiffractometerBruker SMART APEXII DUO CCD area-detector
Absorption correctionMulti-scan
(SADABS; Bruker, 2009)
Tmin, Tmax0.870, 0.942
No. of measured, independent and
observed [I > 2σ(I)] reflections
10764, 2871, 2622
Rint0.019
(sin θ/λ)max1)0.707
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.035, 0.099, 1.08
No. of reflections2871
No. of parameters132
H-atom treatmentH atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å3)0.66, 0.31

Computer programs: APEX2 (Bruker, 2009), SAINT (Bruker, 2009), SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2009).

Hydrogen-bond geometry (Å, º) top
Cg1 is the centroid of the C2–C7 ring.
D—H···AD—HH···AD···AD—H···A
N1—H2N1···Cl1i0.95 (2)2.26 (2)3.2061 (14)173.6 (15)
N1—H3N1···Cl10.99 (2)2.19 (2)3.1496 (12)162.6 (19)
N1—H1N1···Cl1ii0.97 (2)2.27 (2)3.2240 (12)168.4 (19)
C9—H9B···Cl1iii0.992.693.6135 (13)156
C3—H3A···Cg1iv0.952.533.3909 (14)150
Symmetry codes: (i) x+2, y1/2, z+3/2; (ii) x, y+1/2, z+1/2; (iii) x+2, y+1/2, z+3/2; (iv) x+1, y+1/2, z+3/2.
 

Footnotes

Thomson Reuters ResearcherID: A-3561-2009.

§Thomson Reuters ResearcherID: C-7581-2009.

Acknowledgements

HKF and WSL thank Universiti Sains Malaysia (USM) for a Research University Grant (1001/PFIZIK/811160). WSL also thanks the Malaysian government and USM for the position of Research Officer under the Research University Grant No. 1001/PFIZIK/811160.

References

First citationAlvarez-Builla, J., Vaquero, J. J. & Barluenga, J. (2011). Editors. Modern Heterocyclic Chemistry, Vol. 2, pp. 635–1047. Weinheim: Wiley-VCH.  Google Scholar
First citationBruker (2009). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.  Google Scholar
First citationChen, S. B., Tan, J. H., Ou, T. M., Huang, S. L., An, L. K., Luo, H. B., Li, D., Gu, L. Q. & Huang, Z. S. (2011). Bioorg. Med. Chem. Lett. 21, 1004–1009.  Web of Science CrossRef CAS PubMed Google Scholar
First citationCosier, J. & Glazer, A. M. (1986). J. Appl. Cryst. 19, 105–107.  CrossRef CAS Web of Science IUCr Journals Google Scholar
First citationKatritzky, A. R., Ramsden, C. A., Joule, J. A. & Zhdankin, V. V. (2010). Handbook of Heterocyclic Chemistry, 3rd ed. Oxford: Elsevier.  Google Scholar
First citationSheldrick, G. M. (2008). Acta Cryst. A64, 112–122.  Web of Science CrossRef CAS IUCr Journals Google Scholar
First citationSpek, A. L. (2009). Acta Cryst. D65, 148–155.  Web of Science CrossRef CAS IUCr Journals Google Scholar
First citationZhang, J., Zhuang, L. & Wang, G. (2009). Acta Cryst. E65, o2245.  Web of Science CSD CrossRef IUCr Journals Google Scholar

This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890
Follow Acta Cryst. E
Sign up for e-alerts
Follow Acta Cryst. on Twitter
Follow us on facebook
Sign up for RSS feeds