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

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890
Volume 66| Part 7| July 2010| Pages o1555-o1556

2-(3-Bromo-4-meth­­oxy­phen­yl)acetic acid

aDepartment of Chemistry, University of Wisconsin–Madison, 1101 University Ave, Madison, WI 53706, USA
*Correspondence e-mail: iguzei@chem.wisc.edu

(Received 14 May 2010; accepted 27 May 2010; online 5 June 2010)

The title compound C9H9BrO3, was synthesized by the regioselective bromination of 4-meth­oxy­phenyl­acetic acid using bromine in acetic acid in a 84% yield. In the mol­ecular structure, the meth­oxy group is almost coplanar with the phenyl ring within 0.06 Å; the acetic acid substituent is tilted by 78.15 (7)° relative to the ring. The C—C—C angles at the OMe, acetyl and Br substituents are 118.2 (2), 118.4 (2) and 121.5 (2)°, respectively, indicating that the Br atom is electron-withdrawing, whereas the other substituents possess electron-donating properties. In the crystal, the mol­ecules form centrosymmetric strongly O—H⋯O hydrogen-bonded dimers of the type R22(8).

Related literature

For the use of the title compound in the synthesis of natural products such as Combretastatin A-4, see: Zou et al. (2008[Zou, Y., Xiao, C.-F., Zhong, R.-Q., Wei, W., Hunag, W.-M. & He, S.-J. (2008). J. Chem. Res. pp. 354-356.]); for Verongamine, see: Wasserman & Wang (1998[Wasserman, H. H. & Wang, J. (1998). J. Org. Chem. 63, 5581-5586.]) and for model Vancomycin-type systems, see: Ghosh et al. (2009[Ghosh, S., Kumar, A. S., Mehta, G. N. & Soundararajan, R. (2009). Synthesis, pp. 3322-3326.]). The iodo-analogue featured in the synthesis of (+)-Phleichrome and (+)-Calphostin D, see: Morgan et al. (2010[Morgan, B. J., Mulrooney, C. A., O'Brien, E. M. & Kozlowski, M. C. (2010). J. Org. Chem. 75, 30-43.]). For the synthesis of the title compound, see: Coutts et al., (1970[Coutts, I. G. C., Durbin, A. K. & Schofield, K. (1970). Aust. J. Chem. 23, 791-800.]); Morgan et al., (2007[Morgan, B. J., Xie, X., Phuan, P.-W. & Kozlowski, M. C. (2007). J. Org. Chem. 72, 6171-6182.]); Zou et al. (2008[Zou, Y., Xiao, C.-F., Zhong, R.-Q., Wei, W., Hunag, W.-M. & He, S.-J. (2008). J. Chem. Res. pp. 354-356.]); Ghosh et al. (2009[Ghosh, S., Kumar, A. S., Mehta, G. N. & Soundararajan, R. (2009). Synthesis, pp. 3322-3326.]). For background for our program to introduce natural product synthesis, crystal growing techniques and single crystal X-ray diffraction data analysis into the undergraduate curriculum, see: Findlater et al., (2010[Findlater, M., Hill, N. J. & Cowley, A. H. (2010). J. Chem. Crystallogr. 40, 64-66.]); Guzei et al., (2010a[Guzei, I. A., Hill, N. J. & Van Hout, M. R. (2010a). Acta Cryst. E66, o40-o41.]). For a discussion of hydrogen-bonding motif assignment, see: Guzei et al. (2010b[Guzei, I. A., Spencer, L. C., Ainooson, M. K. & Darkwa, J. (2010b). Acta Cryst. C66, m89-m96.]). Outlier reflections were omitted based on the statistics test described by Prince & Nicholson (1983[Prince, E. & Nicholson, W. L. (1983). Acta Cryst. A39, 407-410.]) and Rollett (1988[Rollett, J. S. (1988). Crystallographic Computing, edited by N. W. Isaacs & M. R. Taylor, Vol. 4, pp. 149-166. Oxford University Press.]), and implemented in FCF_filter (Guzei, 2007[Guzei, I. A. (2007). In-house Crystallographic Programs: FCF_filter, INSerter and modiCIFer. Molecular Structure Laboratory, University of Wisconsin-Madison, Madison, Wisconsin, USA.]).

[Scheme 1]

Experimental

Crystal data
  • C9H9BrO3

  • Mr = 245.06

  • Monoclinic, P 21 /c

  • a = 12.5022 (4) Å

  • b = 8.2690 (2) Å

  • c = 9.0199 (3) Å

  • β = 93.573 (1)°

  • V = 930.67 (5) Å3

  • Z = 4

  • Cu Kα radiation

  • μ = 5.81 mm−1

  • T = 120 K

  • 0.46 × 0.37 × 0.19 mm

Data collection
  • Bruker SMART APEXII area-detector diffractometer

  • Absorption correction: analytical (SADABS; Bruker, 2007[Bruker (2007). APEX2, SADABS and SAINT-Plus. Bruker AXS Inc., Madison, Wisconsin, USA.]) Tmin = 0.177, Tmax = 0.398

  • 12598 measured reflections

  • 1725 independent reflections

  • 1708 reflections with I > 2σ(I)

  • Rint = 0.030

Refinement
  • R[F2 > 2σ(F2)] = 0.026

  • wR(F2) = 0.073

  • S = 1.08

  • 1725 reflections

  • 120 parameters

  • H-atom parameters constrained

  • Δρmax = 0.86 e Å−3

  • Δρmin = −0.47 e Å−3

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
O3—H3⋯O2i 0.84 1.82 2.661 (2) 179
Symmetry code: (i) -x+1, -y-1, -z.

Data collection: APEX2 (Bruker, 2007[Bruker (2007). APEX2, SADABS and SAINT-Plus. Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: SAINT-Plus (Bruker, 2007[Bruker (2007). APEX2, SADABS and SAINT-Plus. Bruker AXS Inc., Madison, Wisconsin, USA.]); data reduction: SAINT-Plus; 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: publCIF (Westrip, 2010[Westrip, S. P. (2010). J. Appl. Cryst. 43. Submitted.]) and modiCIFer (Guzei, 2007[Guzei, I. A. (2007). In-house Crystallographic Programs: FCF_filter, INSerter and modiCIFer. Molecular Structure Laboratory, University of Wisconsin-Madison, Madison, Wisconsin, USA.]).

Supporting information


Comment top

Recently, we have been pursuing simple organic and organometallic compounds as candidates for the introduction of (a) natural product synthesis into the undergraduate teaching laboratory and (b) crystal growing techniques and single crystal X-ray diffraction data analysis into the undergraduate curriculum (Findlater et al., 2010; Guzei at al., 2010a). The 3-bromo-4-methoxyphenylacetic acid I has been employed in the synthesis of natural products such as Combretastatin A-4, (Zou et al., 2008), Verongamine (Wasserman & Wang, 1998) and model Vancomycin-type systems (Ghosh et al., 2009). The iodo-analogue features in the synthesis of the perylenequinones (+)-Phleichrome and (+)-Calphostin D, (Morgan et al., 2010). Our interest in I stems from its role in the synthesis of the antimitotic compound Combretastatin A-4 via a simple Perkin condensation/decarboxylation sequence (Zou et al., 2008). This concise route, employing commercially available starting materials, followed by the facile purification of I to furnish high quality crystals makes it ideal in both regards. Compound I is readily synthesized by the regioselective bromination of 4-methoxyphenylacetic acid using bromine in acetic acid (Coutts et al., 1970; Morgan et al., 2007; Zou et al., 2008; Ghosh et al., 2009). Compound I was isolated and characterized by NMR, mp, and single-crystal X-ray analysis. There are three main structural aspects students should identify. First, the positions of the alkyl substituents on the phenyl ring. The methoxy-group is almost coplanar with the ring, torsion angle C7—O1—C1—C6 is 1.2 (3)°, whereas the acetic acid terminus is nearly perpendicular to the ring with the dihedral angle between the planes defined by atoms C1—C6 and atoms C4,C8,C9,O2,O3 spanning 78.15 (7)°. Secondly, the distortions of the C—C—C angles from 120° at the substituents of the phenyl ring reflect their electronic properties. The stronger the electron-withdrawing power of a substituent, the larger the C—C—C angle. The angles at OMe, Ac and Br are 118.2 (2), 118.4 (2), and 121.5 (2)°, respectively, indicating that the Br atom is electron-withdrawing, whereas the other substituents possess electron-donating properties. Of course, the magnitude of the values is affected by the neighbouring substituents. Thirdly, the molecules of I form centrosymmetric strongly hydrogen-bonded dimers in the lattice. The hydrogen bonding motif is R22(8). A topical discussion of hydrogen bonding motif assignment was published by Guzei et al., 2010b.

Related literature top

For the use of the title compound in the synthesis of natural products such as Combretastatin A-4, see: Zou et al. (2008); for Verongamine, see: Wasserman & Wang (1998) and for model Vancomycin-type systems, see: Ghosh et al. (2009). The iodo-analogue featured in the synthesis of (+)-Phleichrome and (+)-Calphostin D, see: Morgan et al. (2010). For the synthesis of the title compound, see: Coutts et al., (1970); Morgan et al., (2007); Zou et al. (2008); Ghosh et al. (2009). For background for our program to introduce natural product synthesis, crystal growing techniques and single crystal X-ray diffraction data analysis into the undergraduate curriculum, see: Findlater et al., (2010); Guzei et al., (2010a). For a discussion of hydrogen-bonding motif assignment, see: Guzei et al. (2010b). Outlier reflections were omitted based on the statistics test described by Prince & Nicholson (1983) and Rollett (1988), and implemented in FCF_filter (Guzei, 2007).

Experimental top

To a stirred solution of 4-methoxyphenylacetic acid (10 g, 60.2 mmol) in acetic acid (60 ml) was added a solution of bromine (9.62 g, 3.1 ml, 60.2 mmol) in acetic acid (30 ml) slowly dropwise over 30 min. The mixture was stirred at room temperature (60 min) and then poured into 500 ml ice–water. The resultant pale yellow, turbid mixture was stirred (10 min), filtered, rinsed with ice–water (3×10 ml), air-dried (20 min) and recrystallized from hot xylene to give a white crystalline powder. Yield 12.41 g, 84 %. M.p. 386.3–387.2 K.

1H NMR (CDCl3): δ 3.56 (2H, s, CH2); 3.89 (3H, s, OCH3), 6.86 (1H, d), 7.19 (1H, dd), 7.48 (1H, d). 13C(1H) NMR (CDCl3): δ 39.9; 56.5; 111.9; 112.2; 127.0; 129.6; 134.6; 155.5; 178.0.

Refinement top

All H-atoms were placed in idealized locations. The C—H distances were 0.98Å for the methyl group, 0.99Å the methylene group, 0.95Å for the sp2-hybridized atoms; the O—H distance was fixed at 0.84Å. All H atoms were refined as riding with thermal displacement coefficients Uiso(H) set to 1.5Ueq(C, O) for the methyl- and hydroxyl-groups and to to 1.2Ueq(C) for the CH- and CH2-groups.

The outlier reflections were omitted based on the statistics test described by Prince & Nicholson, (1983) and Rollett, (1988), and implemented in program FCF_filter (Guzei, 2007). The number of omitted outliers is 4.

Computing details top

Data collection: APEX2 (Bruker, 2007); cell refinement: SAINT-Plus (Bruker, 2007); data reduction: SAINT-Plus (Bruker, 2007); 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: publCIF (Westrip, 2010) and modiCIFer (Guzei, 2007).

Figures top
[Figure 1] Fig. 1. Molecular structure of I with the atom numbering scheme. The displacement ellipsoids are shown at 50% probability level.
2-(3-Bromo-4-methoxyphenyl)acetic acid top
Crystal data top
C9H9BrO3F(000) = 488
Mr = 245.06Dx = 1.749 Mg m3
Monoclinic, P21/cMelting point = 386.3–387.2 K
Hall symbol: -P 2ybcCu Kα radiation, λ = 1.54178 Å
a = 12.5022 (4) ÅCell parameters from 9563 reflections
b = 8.2690 (2) Åθ = 3.5–69.5°
c = 9.0199 (3) ŵ = 5.81 mm1
β = 93.573 (1)°T = 120 K
V = 930.67 (5) Å3Block, colourless
Z = 40.46 × 0.37 × 0.19 mm
Data collection top
Bruker SMART APEXII area-detector
diffractometer
1725 independent reflections
Radiation source: fine-focus sealed tube1708 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.030
0.5° ω and 0.5° ϕ scansθmax = 69.5°, θmin = 3.5°
Absorption correction: analytical
(SADABS; Bruker, 2007)
h = 1415
Tmin = 0.177, Tmax = 0.398k = 910
12598 measured reflectionsl = 1010
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.026Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.073H-atom parameters constrained
S = 1.08 w = 1/[σ2(Fo2) + (0.0442P)2 + 1.1574P]
where P = (Fo2 + 2Fc2)/3
1725 reflections(Δ/σ)max < 0.001
120 parametersΔρmax = 0.86 e Å3
0 restraintsΔρmin = 0.47 e Å3
Crystal data top
C9H9BrO3V = 930.67 (5) Å3
Mr = 245.06Z = 4
Monoclinic, P21/cCu Kα radiation
a = 12.5022 (4) ŵ = 5.81 mm1
b = 8.2690 (2) ÅT = 120 K
c = 9.0199 (3) Å0.46 × 0.37 × 0.19 mm
β = 93.573 (1)°
Data collection top
Bruker SMART APEXII area-detector
diffractometer
1725 independent reflections
Absorption correction: analytical
(SADABS; Bruker, 2007)
1708 reflections with I > 2σ(I)
Tmin = 0.177, Tmax = 0.398Rint = 0.030
12598 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0260 restraints
wR(F2) = 0.073H-atom parameters constrained
S = 1.08Δρmax = 0.86 e Å3
1725 reflectionsΔρmin = 0.47 e Å3
120 parameters
Special details top

Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'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
Br10.253622 (18)0.20274 (3)0.38506 (3)0.02281 (12)
O10.05071 (12)0.0202 (2)0.32075 (17)0.0186 (3)
O20.40281 (14)0.3902 (2)0.05910 (19)0.0234 (4)
O30.50409 (14)0.3283 (2)0.12886 (19)0.0229 (4)
H30.53260.41780.10710.034*
C10.12214 (17)0.0244 (3)0.2209 (2)0.0151 (4)
C20.22340 (18)0.0476 (3)0.2339 (2)0.0148 (4)
C30.30189 (17)0.0087 (3)0.1381 (2)0.0160 (4)
H3A0.37010.05930.14930.019*
C40.28118 (18)0.1041 (3)0.0255 (2)0.0172 (5)
C50.1810 (2)0.1765 (3)0.0129 (3)0.0201 (5)
H50.16610.25420.06310.024*
C60.10183 (18)0.1383 (3)0.1087 (3)0.0181 (5)
H60.03390.18980.09770.022*
C70.05187 (18)0.0591 (3)0.3100 (3)0.0220 (5)
H7A0.08870.03460.21350.033*
H7C0.09520.02040.38960.033*
H7B0.04160.17620.31950.033*
C80.3654 (2)0.1464 (3)0.0810 (3)0.0209 (5)
H8A0.41750.05640.08310.025*
H8B0.33060.15760.18210.025*
C90.42502 (19)0.3007 (3)0.0408 (3)0.0170 (5)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Br10.02043 (17)0.02308 (18)0.02445 (17)0.00116 (9)0.00227 (11)0.00996 (9)
O10.0164 (7)0.0206 (8)0.0193 (8)0.0018 (6)0.0047 (6)0.0044 (6)
O20.0309 (9)0.0194 (8)0.0214 (9)0.0053 (7)0.0119 (7)0.0032 (7)
O30.0222 (9)0.0241 (9)0.0236 (9)0.0068 (7)0.0096 (7)0.0059 (7)
C10.0169 (10)0.0131 (10)0.0152 (10)0.0020 (8)0.0009 (8)0.0024 (8)
C20.0193 (10)0.0110 (10)0.0137 (10)0.0010 (8)0.0029 (8)0.0009 (8)
C30.0163 (10)0.0137 (10)0.0180 (10)0.0004 (8)0.0005 (8)0.0035 (8)
C40.0210 (11)0.0152 (11)0.0157 (11)0.0040 (9)0.0041 (8)0.0040 (8)
C50.0252 (12)0.0181 (11)0.0169 (11)0.0004 (9)0.0013 (9)0.0035 (9)
C60.0189 (11)0.0165 (11)0.0188 (11)0.0030 (9)0.0005 (9)0.0020 (9)
C70.0160 (11)0.0241 (12)0.0262 (12)0.0026 (9)0.0028 (9)0.0010 (10)
C80.0246 (12)0.0211 (12)0.0176 (11)0.0032 (10)0.0072 (9)0.0016 (9)
C90.0178 (11)0.0188 (12)0.0145 (11)0.0014 (8)0.0019 (9)0.0039 (8)
Geometric parameters (Å, º) top
Br1—C21.893 (2)C4—C51.386 (3)
O1—C11.359 (3)C4—C81.510 (3)
O1—C71.438 (3)C5—C61.390 (3)
O2—C91.212 (3)C5—H50.9500
O3—C91.326 (3)C6—H60.9500
O3—H30.8400C7—H7A0.9800
C1—C61.394 (3)C7—H7C0.9800
C1—C21.397 (3)C7—H7B0.9800
C2—C31.385 (3)C8—C91.510 (3)
C3—C41.392 (3)C8—H8A0.9900
C3—H3A0.9500C8—H8B0.9900
C1—O1—C7116.85 (18)C5—C6—H6120.0
C9—O3—H3109.5C1—C6—H6120.0
O1—C1—C6124.6 (2)O1—C7—H7A109.5
O1—C1—C2117.3 (2)O1—C7—H7C109.5
C6—C1—C2118.2 (2)H7A—C7—H7C109.5
C3—C2—C1121.5 (2)O1—C7—H7B109.5
C3—C2—Br1119.28 (17)H7A—C7—H7B109.5
C1—C2—Br1119.23 (17)H7C—C7—H7B109.5
C2—C3—C4120.3 (2)C4—C8—C9113.34 (19)
C2—C3—H3A119.9C4—C8—H8A108.9
C4—C3—H3A119.9C9—C8—H8A108.9
C5—C4—C3118.4 (2)C4—C8—H8B108.9
C5—C4—C8120.7 (2)C9—C8—H8B108.9
C3—C4—C8120.9 (2)H8A—C8—H8B107.7
C4—C5—C6121.7 (2)O2—C9—O3123.7 (2)
C4—C5—H5119.2O2—C9—C8124.2 (2)
C6—C5—H5119.2O3—C9—C8112.16 (19)
C5—C6—C1120.0 (2)
C7—O1—C1—C61.2 (3)C3—C4—C5—C60.4 (3)
C7—O1—C1—C2177.70 (19)C8—C4—C5—C6179.3 (2)
O1—C1—C2—C3179.39 (19)C4—C5—C6—C10.1 (4)
C6—C1—C2—C30.4 (3)O1—C1—C6—C5179.4 (2)
O1—C1—C2—Br11.0 (3)C2—C1—C6—C50.5 (3)
C6—C1—C2—Br1180.00 (17)C5—C4—C8—C981.5 (3)
C1—C2—C3—C40.1 (3)C3—C4—C8—C998.8 (3)
Br1—C2—C3—C4179.53 (17)C4—C8—C9—O25.8 (3)
C2—C3—C4—C50.5 (3)C4—C8—C9—O3175.0 (2)
C2—C3—C4—C8179.2 (2)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O3—H3···O2i0.841.822.661 (2)179
Symmetry code: (i) x+1, y1, z.

Experimental details

Crystal data
Chemical formulaC9H9BrO3
Mr245.06
Crystal system, space groupMonoclinic, P21/c
Temperature (K)120
a, b, c (Å)12.5022 (4), 8.2690 (2), 9.0199 (3)
β (°) 93.573 (1)
V3)930.67 (5)
Z4
Radiation typeCu Kα
µ (mm1)5.81
Crystal size (mm)0.46 × 0.37 × 0.19
Data collection
DiffractometerBruker SMART APEXII area-detector
diffractometer
Absorption correctionAnalytical
(SADABS; Bruker, 2007)
Tmin, Tmax0.177, 0.398
No. of measured, independent and
observed [I > 2σ(I)] reflections
12598, 1725, 1708
Rint0.030
(sin θ/λ)max1)0.607
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.026, 0.073, 1.08
No. of reflections1725
No. of parameters120
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.86, 0.47

Computer programs: APEX2 (Bruker, 2007), SAINT-Plus (Bruker, 2007), SHELXTL (Sheldrick, 2008), publCIF (Westrip, 2010) and modiCIFer (Guzei, 2007).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O3—H3···O2i0.841.822.661 (2)178.8
Symmetry code: (i) x+1, y1, z.
 

References

First citationBruker (2007). APEX2, SADABS and SAINT-Plus. Bruker AXS Inc., Madison, Wisconsin, USA.  Google Scholar
First citationCoutts, I. G. C., Durbin, A. K. & Schofield, K. (1970). Aust. J. Chem. 23, 791–800.  CrossRef CAS Google Scholar
First citationFindlater, M., Hill, N. J. & Cowley, A. H. (2010). J. Chem. Crystallogr. 40, 64–66.  Web of Science CSD CrossRef CAS Google Scholar
First citationGhosh, S., Kumar, A. S., Mehta, G. N. & Soundararajan, R. (2009). Synthesis, pp. 3322–3326.  Google Scholar
First citationGuzei, I. A. (2007). In-house Crystallographic Programs: FCF_filter, INSerter and modiCIFer. Molecular Structure Laboratory, University of Wisconsin–Madison, Madison, Wisconsin, USA.  Google Scholar
First citationGuzei, I. A., Hill, N. J. & Van Hout, M. R. (2010a). Acta Cryst. E66, o40–o41.  Web of Science CSD CrossRef IUCr Journals Google Scholar
First citationGuzei, I. A., Spencer, L. C., Ainooson, M. K. & Darkwa, J. (2010b). Acta Cryst. C66, m89–m96.  Web of Science CSD CrossRef IUCr Journals Google Scholar
First citationMorgan, B. J., Mulrooney, C. A., O'Brien, E. M. & Kozlowski, M. C. (2010). J. Org. Chem. 75, 30–43.  Web of Science CrossRef PubMed CAS Google Scholar
First citationMorgan, B. J., Xie, X., Phuan, P.-W. & Kozlowski, M. C. (2007). J. Org. Chem. 72, 6171–6182.  Web of Science CrossRef PubMed CAS Google Scholar
First citationPrince, E. & Nicholson, W. L. (1983). Acta Cryst. A39, 407–410.  CrossRef CAS IUCr Journals Google Scholar
First citationRollett, J. S. (1988). Crystallographic Computing, edited by N. W. Isaacs & M. R. Taylor, Vol. 4, pp. 149–166. Oxford University Press.  Google Scholar
First citationSheldrick, G. M. (2008). Acta Cryst. A64, 112–122.  Web of Science CrossRef CAS IUCr Journals Google Scholar
First citationWasserman, H. H. & Wang, J. (1998). J. Org. Chem. 63, 5581–5586.  Web of Science CrossRef CAS Google Scholar
First citationWestrip, S. P. (2010). J. Appl. Cryst. 43. Submitted.  Google Scholar
First citationZou, Y., Xiao, C.-F., Zhong, R.-Q., Wei, W., Hunag, W.-M. & He, S.-J. (2008). J. Chem. Res. pp. 354–356.  Web of Science CrossRef 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
Volume 66| Part 7| July 2010| Pages o1555-o1556
Follow Acta Cryst. E
Sign up for e-alerts
Follow Acta Cryst. on Twitter
Follow us on facebook
Sign up for RSS feeds