PMCCPMCCPMCC

Search tips
Search criteria 

Advanced

 
Logo of actaeInternational Union of Crystallographysearchopen accessarticle submissionjournal home pagethis article
 
Acta Crystallogr Sect E Struct Rep Online. 2010 January 1; 66(Pt 1): o121.
Published online 2009 December 12. doi:  10.1107/S1600536809051873
PMCID: PMC2980079

N-{4-[4-(4-Fluoro­phen­yl)-1-methyl-2-[(R)-methyl­sulfin­yl]-1H-imidazol-5-yl]-2-pyridyl}acetamide dihydrate

Abstract

In the crystal structure of the title compound, C18H17FN4O2S·2H2O, the organic mol­ecules are linked by inter­molecular O—H(...)O, O—H(...)N and N—H(...)O hydrogen bonds with the water mol­ecules, generating a three-dimensional network. The imidazole ring system forms a dihedral angle of 24.9 (2)° with the 4-fluoro­phenyl ring. The pyridine ring is oriented approximately perpendicular [72.24 (8)°] to the imidazole ring system.

Related literature

For general background and the biological activity of chiral sulfoxides and their potential use as therapeutic agents, see: Jia et al., (2004 [triangle]). Sulfoxide enanti­omers can differ in their pharmacodynamic and/or pharmacokinetic properties, see: Lu (2007 [triangle]). For the preparation of tri- and tetra­substituted 2-thio­imidazoles, see: Wagner et al. (2003 [triangle]); Laufer, Hauser, Domeyer et al. (2008 [triangle]); Laufer, Hauser & Liedtke (2008 [triangle]).

An external file that holds a picture, illustration, etc.
Object name is e-66-0o121-scheme1.jpg

Experimental

Crystal data

  • C18H17FN4O2S·2H2O
  • M r = 408.45
  • Orthorhombic, An external file that holds a picture, illustration, etc.
Object name is e-66-0o121-efi1.jpg
  • a = 5.8178 (2) Å
  • b = 14.3233 (5) Å
  • c = 23.3694 (9) Å
  • V = 1947.37 (12) Å3
  • Z = 4
  • Mo Kα radiation
  • μ = 0.21 mm−1
  • T = 193 K
  • 0.50 × 0.10 × 0.10 mm

Data collection

  • Bruker SMART APEXII diffractometer
  • 10703 measured reflections
  • 4628 independent reflections
  • 2634 reflections with I > 2σ(I)
  • R int = 0.089

Refinement

  • R[F 2 > 2σ(F 2)] = 0.046
  • wR(F 2) = 0.099
  • S = 0.84
  • 4628 reflections
  • 256 parameters
  • H-atom parameters constrained
  • Δρmax = 0.27 e Å−3
  • Δρmin = −0.30 e Å−3
  • Absolute structure: Flack (1983 [triangle]), 1949 Friedel pairs
  • Flack parameter: −0.08 (11)

Data collection: APEX2 (Bruker, 2006 [triangle]); cell refinement: SAINT (Bruker, 2006 [triangle]); data reduction: SAINT; program(s) used to solve structure: SIR97 (Altomare et al., 1999 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 [triangle]); molecular graphics: PLATON (Spek, 2009 [triangle]); software used to prepare material for publication: PLATON.

Table 1
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536809051873/nc2170sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809051873/nc2170Isup2.hkl

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Acknowledgments

The authors thank the Federal Ministry of Education and Research, Germany, Merckle GmbH, Ulm, Germany, and the Fonds der Chemischen Industrie, Germany, for their generous support of this work.

supplementary crystallographic information

Comment

Many chiral sulfoxides exhibit interesting biological activities and show promise as therapeutic agents (Jia et al., 2004). The title compound, N-(4-(4-(4-fluorophenyl)-1-methyl-2-((R)-methylsulfinyl)-1H-imidazol-5-yl) pyridin-2-yl)acetamide, was prepared in the course of our studies on tri- and tetrasubstituted 2-thioimidazoles as p38 mitogen-activated protein (MAP) kinase inhibitors (Wagner et al., 2003, Laufer, Hauser, Domeyer et al.,2008); Laufer, Hauser & Liedtke, 2008). The oxidation of the sulfide N-(4-(4-(4-fluorophenyl)-1-methyl-2-(methylthio)-1H-imidazol-5-yl)pyridin-2- yl)acetamide with sodium periodate as oxidant yields the corresponding sulfoxide N-(4-(4-(4-fluorophenyl)-1-methyl-2-(methylsulfinyl)-1H-imidazol-5-yl) pyridin-2-yl)acetamide. This compound has a centre of asymmetry in the sulfur atom meaning that two sulfoxide enantiomers exist, which can differ in pharmacodynamic and/or pharmacokinetic properties (Lu, 2007). The both enantiomers were separated by enantioselective preparative HPLC. To identify the absolute configurations of the enantiomers according to the Cahn-Ingold-Prelog-nomenclature X-ray analysis was used. In this article we present the X-ray data of the first eluted enantiomer I. The analysis of the crystal structure shows that the N24 amino- group of the acetamide moiety of the one imidazole-molecule interact with another imidazole ring system by the building of one intermolecular hydrogen bond N—H···O to the sulfoxide oxygen-atom O15, whereas the O15···H24 distance is 2.08 Å. Furthermore, the carbonyl-oxygen atom O26 of the acetamide-moiety of a third imidazole molecule is linked over two water molecules to the sulfoxide oxygen-atom O15 and to the nitrogen atom N2 of the imidazole core by the building of intermolecular O1L—H1L···O26 (1.90 Å), O1L—H2L···O15 (2.00 Å) and O2L—H4L···N2 (2.51 Å) hydrogen bonds. The imidazole ring system forms a dihedral angle of 24.9 (1)° to the 4-fluorophenyl ring. The pyridine ring is oriented approximately perpendicular (72.24 (8)°) to the imidazole ring system. According to the Cahn-Ingold-Prelog-nomenclature the first eluted enantiomer I is (R)-configurated.

Experimental

N-(4-(4-(4-fluorophenyl)-1-methyl-2-(methylthio)-1H-imidazol-5-yl)pyridin-2- yl)acetamide (3.56 g, 10 mmol) was dissolved in a mixture of THF (30 ml) and acetone (58 ml), and water (45 ml) was added. The mixture was stirred at T = 313 K, and an aqueous solution of sodium periodate (4.01 g, 18.4 mmol in 65 ml water) was added dropwise. The reaction mixture was heated at T = 338 K. The progress was again monitored until HPLC analysis (C8 Betasil, MeOH/ 0.01 M KH2PO4, pH = 2,3) indicated complete conversion. After cooling to rt, the organic solvents were removed under reduced pressure and a precipitate dropped down, which was filtered off and washed with water and isopropylether. The crude product was purified by recrystallization from ethylacetate to yield 3.02 g (81.2%) of the colorless racemic product N-(4-(4-(4-fluorophenyl)-1-methyl-2-(methylsulfinyl)-1H-imidazol-5-yl)pyridin-2-yl)acetamide. The both enantiomers were isolated by enantioselective preparative HPLC (Daicel CHIRALPAK AD, CH2Cl2 / MeOH/ TEA 98: 2: 0.1). Suitable crystals of the first eluted enantiomer I for X-ray were obtained by slow evaporation at T = 298 K of a solution of ethanol.

Refinement

Hydrogen atoms attached to carbons were placed at calculated positions with C—H = 0.95 Å (aromatic) or 0.98–0.99 Å (sp3 C-atom). Hydrogen atoms attached to nitrogen and oxygen were located in diff. Fourier maps. All H atoms were refined in the riding-model approximation with isotropic displacement parameters (set at 1.2–1.5 times of the Ueq of the parent atom). The absolute structure was determined on the basis of 1949 Friedel pairs.

Figures

Fig. 1.
View of compound I. Displacement ellipsoids are drawn at the 50% probability level.

Crystal data

C18H17FN4O2S·2H2OF(000) = 856
Mr = 408.45Dx = 1.393 Mg m3
Orthorhombic, P212121Mo Kα radiation, λ = 0.71069 Å
Hall symbol: P 2ac 2abCell parameters from 1669 reflections
a = 5.8178 (2) Åθ = 2.9–23.5°
b = 14.3233 (5) ŵ = 0.21 mm1
c = 23.3694 (9) ÅT = 193 K
V = 1947.37 (12) Å3Needle, colourless
Z = 40.50 × 0.10 × 0.10 mm

Data collection

Bruker SMART APEXII diffractometer2634 reflections with I > 2σ(I)
Radiation source: sealed TubeRint = 0.089
graphiteθmax = 27.9°, θmin = 1.7°
CCD scanh = −7→7
10703 measured reflectionsk = −18→15
4628 independent reflectionsl = −24→30

Refinement

Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.046H-atom parameters constrained
wR(F2) = 0.099w = 1/[σ2(Fo2) + (0.0293P)2] where P = (Fo2 + 2Fc2)/3
S = 0.84(Δ/σ)max = 0.001
4628 reflectionsΔρmax = 0.27 e Å3
256 parametersΔρmin = −0.29 e Å3
0 restraintsAbsolute structure: Flack (1983), 1949 Friedel pairs
Primary atom site location: structure-invariant direct methodsFlack parameter: −0.08 (11)

Special details

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)

xyzUiso*/Ueq
C1−0.0028 (5)0.38294 (18)0.67677 (10)0.0247 (6)
N20.0086 (5)0.38684 (16)0.73573 (9)0.0301 (6)
C30.1670 (5)0.44957 (18)0.74681 (10)0.0299 (7)
N40.2625 (4)0.48701 (15)0.69850 (7)0.0276 (5)
C50.1496 (5)0.44518 (18)0.65318 (10)0.0244 (6)
C6−0.1622 (5)0.31718 (18)0.64897 (11)0.0265 (7)
C7−0.1212 (6)0.2827 (2)0.59361 (11)0.0334 (7)
H70.01390.30080.57360.040*
C8−0.2761 (6)0.2227 (2)0.56802 (13)0.0406 (8)
H8−0.25040.20030.53030.049*
C9−0.4667 (6)0.1961 (2)0.59797 (14)0.0428 (9)
C10−0.5117 (6)0.2250 (2)0.65250 (13)0.0391 (8)
H10−0.64380.20360.67250.047*
C11−0.3591 (5)0.2864 (2)0.67776 (12)0.0326 (7)
H11−0.38850.30820.71540.039*
F13−0.6195 (4)0.13680 (13)0.57211 (9)0.0687 (6)
S140.25518 (17)0.48524 (5)0.81652 (3)0.0404 (2)
O150.3625 (4)0.40219 (16)0.84497 (7)0.0490 (6)
C16−0.0249 (7)0.4982 (3)0.84489 (11)0.0636 (12)
H16C−0.01510.51040.88610.095*
H16B−0.11270.44080.83830.095*
H16A−0.10200.55060.82600.095*
C170.4374 (6)0.5604 (2)0.69480 (12)0.0439 (9)
H17A0.41800.60410.72670.066*
H17B0.42050.59400.65850.066*
H17C0.59060.53210.69670.066*
C180.2057 (5)0.47072 (17)0.59317 (9)0.0244 (6)
C190.4114 (5)0.44302 (19)0.56902 (11)0.0285 (7)
H190.52090.40920.59090.034*
C200.4555 (6)0.4653 (2)0.51252 (11)0.0331 (7)
H200.59620.44480.49610.040*
N210.3106 (4)0.51404 (17)0.47977 (8)0.0294 (6)
C220.1152 (5)0.54307 (19)0.50371 (11)0.0262 (7)
C230.0530 (5)0.52212 (19)0.56027 (10)0.0264 (6)
H23−0.08960.54260.57560.032*
N24−0.0213 (4)0.59582 (16)0.46634 (9)0.0314 (6)
H240.02210.59700.42910.047*
C25−0.1937 (6)0.65639 (19)0.47982 (12)0.0327 (7)
O26−0.2713 (4)0.66543 (13)0.52821 (8)0.0405 (5)
C27−0.2867 (7)0.7123 (2)0.43046 (12)0.0530 (10)
H27A−0.25010.77840.43610.080*
H27C−0.45380.70440.42840.080*
H27B−0.21660.69040.39480.080*
O1L0.2647 (6)0.21319 (16)0.85452 (9)0.0726 (8)
H1L0.27170.20570.89450.109*
H2L0.24480.27230.85570.109*
O2L0.0400 (5)0.16661 (18)0.75536 (11)0.0795 (9)
H3L0.10510.18060.78630.119*
H4L−0.03570.21270.74350.119*

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
C10.0296 (16)0.0238 (15)0.0207 (13)0.0027 (13)−0.0021 (14)0.0000 (11)
N20.0400 (16)0.0291 (14)0.0211 (11)−0.0024 (12)−0.0021 (12)0.0038 (10)
C30.0408 (19)0.0302 (15)0.0186 (13)−0.0020 (14)−0.0058 (14)0.0009 (11)
N40.0324 (13)0.0299 (12)0.0206 (10)−0.0038 (13)−0.0037 (12)0.0004 (9)
C50.0266 (17)0.0261 (14)0.0206 (13)0.0042 (13)−0.0028 (13)0.0002 (11)
C60.0312 (19)0.0238 (14)0.0245 (13)0.0029 (13)−0.0061 (14)0.0038 (11)
C70.0332 (18)0.0328 (17)0.0341 (16)0.0031 (16)−0.0017 (15)−0.0034 (13)
C80.044 (2)0.0349 (17)0.0434 (16)0.0021 (19)−0.0093 (19)−0.0141 (14)
C90.036 (2)0.0325 (19)0.060 (2)−0.0051 (17)−0.0175 (19)−0.0050 (16)
C100.0320 (19)0.0342 (18)0.0512 (19)−0.0045 (16)−0.0054 (17)0.0131 (15)
C110.0333 (18)0.0325 (17)0.0318 (15)0.0013 (15)−0.0020 (15)0.0071 (13)
F130.0562 (14)0.0548 (13)0.0950 (15)−0.0195 (12)−0.0165 (14)−0.0227 (12)
S140.0586 (5)0.0411 (4)0.0215 (3)−0.0017 (5)−0.0099 (4)−0.0032 (3)
O150.0636 (17)0.0592 (15)0.0243 (10)0.0236 (14)−0.0124 (11)−0.0030 (10)
C160.072 (3)0.091 (3)0.0272 (15)0.030 (3)−0.0050 (18)−0.0117 (18)
C170.048 (2)0.046 (2)0.0385 (17)−0.0163 (17)−0.0022 (17)0.0006 (14)
C180.0316 (18)0.0237 (14)0.0180 (12)−0.0032 (14)−0.0011 (12)−0.0002 (10)
C190.0288 (17)0.0322 (17)0.0243 (14)0.0034 (14)−0.0031 (14)0.0050 (12)
C200.0310 (18)0.040 (2)0.0288 (15)0.0034 (15)0.0038 (14)0.0011 (13)
N210.0311 (15)0.0318 (13)0.0254 (11)0.0066 (12)0.0012 (11)0.0013 (10)
C220.0313 (18)0.0258 (16)0.0214 (13)−0.0029 (14)−0.0005 (13)−0.0007 (11)
C230.0289 (17)0.0288 (16)0.0214 (13)0.0013 (14)0.0018 (12)−0.0020 (12)
N240.0385 (16)0.0373 (15)0.0185 (11)0.0101 (14)0.0004 (12)0.0032 (10)
C250.037 (2)0.0295 (16)0.0318 (15)0.0049 (15)−0.0035 (15)−0.0010 (12)
O260.0463 (14)0.0462 (12)0.0289 (10)0.0108 (13)0.0015 (12)−0.0037 (9)
C270.065 (3)0.052 (2)0.0415 (17)0.026 (2)−0.006 (2)0.0082 (15)
O1L0.105 (2)0.0615 (16)0.0516 (13)0.0245 (19)0.0045 (17)−0.0070 (12)
O2L0.086 (2)0.0676 (18)0.0850 (18)−0.0002 (17)−0.0200 (19)0.0271 (15)

Geometric parameters (Å, °)

C1—C51.373 (4)C17—H17A0.9800
C1—N21.380 (3)C17—H17B0.9800
C1—C61.473 (4)C17—H17C0.9800
N2—C31.313 (4)C18—C191.381 (4)
C3—N41.368 (3)C18—C231.386 (4)
C3—S141.783 (3)C19—C201.382 (3)
N4—C51.383 (3)C19—H190.9500
N4—C171.465 (4)C20—N211.336 (3)
C5—C181.485 (3)C20—H200.9500
C6—C111.400 (4)N21—C221.333 (3)
C6—C71.405 (4)C22—N241.402 (3)
C7—C81.382 (4)C22—C231.403 (3)
C7—H70.9500C23—H230.9500
C8—C91.365 (5)N24—C251.363 (4)
C8—H80.9500N24—H240.9072
C9—C101.365 (4)C25—O261.224 (3)
C9—F131.370 (4)C25—C271.505 (4)
C10—C111.382 (4)C27—H27A0.9800
C10—H100.9500C27—H27C0.9800
C11—H110.9500C27—H27B0.9800
S14—O151.499 (2)O1L—H1L0.9410
S14—C161.769 (4)O1L—H2L0.8545
C16—H16C0.9800O2L—H3L0.8400
C16—H16B0.9800O2L—H4L0.8400
C16—H16A0.9800
C5—C1—N2110.1 (2)H16C—C16—H16A109.5
C5—C1—C6130.1 (2)H16B—C16—H16A109.5
N2—C1—C6119.8 (2)N4—C17—H17A109.5
C3—N2—C1105.0 (2)N4—C17—H17B109.5
N2—C3—N4113.0 (2)H17A—C17—H17B109.5
N2—C3—S14125.3 (2)N4—C17—H17C109.5
N4—C3—S14121.7 (2)H17A—C17—H17C109.5
C3—N4—C5105.6 (2)H17B—C17—H17C109.5
C3—N4—C17127.7 (2)C19—C18—C23118.7 (2)
C5—N4—C17126.5 (2)C19—C18—C5120.3 (2)
C1—C5—N4106.3 (2)C23—C18—C5120.9 (2)
C1—C5—C18132.9 (2)C18—C19—C20119.0 (3)
N4—C5—C18120.8 (2)C18—C19—H19120.5
C11—C6—C7118.1 (3)C20—C19—H19120.5
C11—C6—C1120.3 (2)N21—C20—C19123.4 (3)
C7—C6—C1121.6 (3)N21—C20—H20118.3
C8—C7—C6120.4 (3)C19—C20—H20118.3
C8—C7—H7119.8C22—N21—C20117.4 (2)
C6—C7—H7119.8N21—C22—N24112.9 (2)
C9—C8—C7118.8 (3)N21—C22—C23123.3 (3)
C9—C8—H8120.6N24—C22—C23123.8 (3)
C7—C8—H8120.6C18—C23—C22118.1 (3)
C10—C9—C8123.4 (3)C18—C23—H23121.0
C10—C9—F13118.4 (3)C22—C23—H23121.0
C8—C9—F13118.3 (3)C25—N24—C22128.0 (2)
C9—C10—C11117.9 (3)C25—N24—H24114.5
C9—C10—H10121.0C22—N24—H24116.8
C11—C10—H10121.0O26—C25—N24123.5 (2)
C10—C11—C6121.4 (3)O26—C25—C27121.3 (3)
C10—C11—H11119.3N24—C25—C27115.2 (3)
C6—C11—H11119.3C25—C27—H27A109.5
O15—S14—C16107.50 (16)C25—C27—H27C109.5
O15—S14—C3107.32 (12)H27A—C27—H27C109.5
C16—S14—C396.18 (15)C25—C27—H27B109.5
S14—C16—H16C109.5H27A—C27—H27B109.5
S14—C16—H16B109.5H27C—C27—H27B109.5
H16C—C16—H16B109.5H1L—O1L—H2L94.9
S14—C16—H16A109.5H3L—O2L—H4L109.5
C5—C1—N2—C3−0.7 (3)F13—C9—C10—C11−178.6 (3)
C6—C1—N2—C3178.7 (3)C9—C10—C11—C6−1.1 (4)
C1—N2—C3—N4−0.4 (3)C7—C6—C11—C10−0.9 (4)
C1—N2—C3—S14179.4 (2)C1—C6—C11—C10179.8 (3)
N2—C3—N4—C51.4 (3)N2—C3—S14—O1564.5 (3)
S14—C3—N4—C5−178.5 (2)N4—C3—S14—O15−115.7 (2)
N2—C3—N4—C17177.9 (3)N2—C3—S14—C16−46.0 (3)
S14—C3—N4—C17−2.0 (4)N4—C3—S14—C16133.8 (3)
N2—C1—C5—N41.5 (3)C1—C5—C18—C19−107.8 (4)
C6—C1—C5—N4−177.8 (3)N4—C5—C18—C1971.7 (3)
N2—C1—C5—C18−178.9 (3)C1—C5—C18—C2371.8 (4)
C6—C1—C5—C181.8 (5)N4—C5—C18—C23−108.7 (3)
C3—N4—C5—C1−1.7 (3)C23—C18—C19—C20−1.7 (4)
C17—N4—C5—C1−178.2 (3)C5—C18—C19—C20177.9 (3)
C3—N4—C5—C18178.7 (2)C18—C19—C20—N211.2 (4)
C17—N4—C5—C182.1 (4)C19—C20—N21—C220.8 (4)
C5—C1—C6—C11−155.5 (3)C20—N21—C22—N24178.2 (2)
N2—C1—C6—C1125.2 (4)C20—N21—C22—C23−2.3 (4)
C5—C1—C6—C725.2 (5)C19—C18—C23—C220.3 (4)
N2—C1—C6—C7−154.0 (3)C5—C18—C23—C22−179.3 (2)
C11—C6—C7—C82.1 (4)N21—C22—C23—C181.8 (4)
C1—C6—C7—C8−178.6 (3)N24—C22—C23—C18−178.8 (3)
C6—C7—C8—C9−1.3 (4)N21—C22—N24—C25−160.2 (3)
C7—C8—C9—C10−0.8 (5)C23—C22—N24—C2520.3 (4)
C7—C8—C9—F13179.8 (3)C22—N24—C25—O26−8.5 (5)
C8—C9—C10—C112.0 (5)C22—N24—C25—C27172.0 (3)

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
N24—H24···O15i0.912.082.983 (3)177
O1L—H2L···O150.852.002.775 (3)151
O1L—H1L···O26ii0.941.902.825 (3)169
O2L—H3L···O1L0.841.902.743 (4)177
O2L—H4L···N20.842.513.193 (3)138

Symmetry codes: (i) −x+1/2, −y+1, z−1/2; (ii) −x, y−1/2, −z+3/2.

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: NC2170).

References

  • 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.
  • Bruker (2006). APEX2, SAINT and SADABS Bruker AXS Inc., Madison, Wisconsin, USA.
  • Flack, H. D. (1983). Acta Cryst. A39, 876–881.
  • Jia, X., Li, X., Xu, L., Li, Y., Shi, Q., Au-Yeung, T. T.-L., Yip, C. W., Yao, X. & Chan, A. S. C. (2004). Adv. Synth. Catal.346, 723–726.
  • Laufer, S. A., Hauser, D. R. J., Domeyer, D. M., Kinkel, K. & Liedtke, A. J. (2008). J. Med. Chem.51, 4122–4149. [PubMed]
  • Laufer, S. A., Hauser, D. R. J. & Liedtke, A. J. (2008). Synthesis, 2, 253–266.
  • Lu, H. (2007). Exp. Opin. Drug Metab. Toxicol.3, 149–158. [PubMed]
  • Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. [PubMed]
  • Spek, A. L. (2009). Acta Cryst. D65, 148–155. [PMC free article] [PubMed]
  • Wagner, G. K., Kotschenreuther, D., Zimmermann, W. & Laufer, S. A. (2003). J. Org. Chem.68, 4527–4530. [PubMed]

Articles from Acta Crystallographica Section E: Structure Reports Online are provided here courtesy of International Union of Crystallography