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Acta Crystallogr Sect E Struct Rep Online. 2008 August 1; 64(Pt 8): o1423–o1424.
Published online 2008 July 5. doi:  10.1107/S1600536808020102
PMCID: PMC2962057

(3R,3aS,6aR)-2,5-Dimethyl-3-(5-phenyl-2-thien­yl)perhydro­pyrrolo[3,4-d][1,2]oxazole-4,6-dione

Abstract

The crystal structure of the title compound, C17H16N2O3S, exhibits intra­molecular C—H(...)S and inter­molecular C—H(...)S and C—H(...)O hydrogen bonds, C—S(...)N [S(...)N = 3.033 (2) Å and C—S(...)N = 142.76 (9)°] inter­actions, and C—H(...)π inter­actions; these inter­actions generate S(4), S(6) and R 2 2(14) ring motifs. The isoxazole ring adopts an envelope conformation, with the N atom displaced by 0.672 (2) Å from the plane of the other ring atoms. The thio­phene ring is oriented with respect to the succinimide and phenyl rings at dihedral angles of 40.03 (12) and 5.21 (13)°, respectively. The dihedral angle between the succinimide and phenyl rings is 39.38 (12)°.

Related literature

For general background, see: Huisgen (1960 [triangle]); Black et al. (1975 [triangle]); Richman (2001 [triangle]); De Clercq (2002 [triangle]); Donadas et al. (2004 [triangle]); Merino et al. (2003 [triangle]); Chiacchio et al. (2003 [triangle]); Iannazzo et al. (2002 [triangle]). For related literature, see: Heaney et al. (2001 [triangle]). For ring motif details, see: Bernstein et al. (1995 [triangle]); Etter (1990 [triangle]).

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Object name is e-64-o1423-scheme1.jpg

Experimental

Crystal data

  • C17H16N2O3S
  • M r = 328.38
  • Orthorhombic, An external file that holds a picture, illustration, etc.
Object name is e-64-o1423-efi2.jpg
  • a = 12.7768 (7) Å
  • b = 10.9803 (6) Å
  • c = 11.1069 (9) Å
  • V = 1558.22 (17) Å3
  • Z = 4
  • Mo Kα radiation
  • μ = 0.22 mm−1
  • T = 296 K
  • 0.65 × 0.46 × 0.27 mm

Data collection

  • Stoe IPDSII diffractometer
  • Absorption correction: integration (X-RED32; Stoe & Cie, 2002 [triangle]) T min = 0.889, T max = 0.935
  • 6395 measured reflections
  • 3332 independent reflections
  • 2899 reflections with I > 2σ(I)
  • R int = 0.051

Refinement

  • R[F 2 > 2σ(F 2)] = 0.037
  • wR(F 2) = 0.099
  • S = 1.04
  • 3332 reflections
  • 221 parameters
  • 1 restraint
  • H atoms treated by a mixture of independent and constrained refinement
  • Δρmax = 0.22 e Å−3
  • Δρmin = −0.22 e Å−3
  • Absolute structure: Flack (1983 [triangle]), 1451 Friedel pairs
  • Flack parameter = −0.13 (8)

Data collection: X-AREA (Stoe & Cie, 2002 [triangle]); cell refinement: X-AREA; data reduction: X-RED32 (Stoe & Cie, 2002 [triangle]); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 [triangle]); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997 [triangle]); software used to prepare material for publication: WinGX (Farrugia, 1999 [triangle]).

Table 1
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536808020102/hk2484sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808020102/hk2484Isup2.hkl

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

Acknowledgments

The authors acknowledge the Faculty of Arts and Sciences, Ondokuz Mayıs University, Turkey, for the use of the Stoe IPDSII diffractometer (purchased under grant F.279 of the University Research Fund).

supplementary crystallographic information

Comment

A general principle for the synthesis of five-membered rings was introduced in 1960 as 1,3-dipolar cycloaddition and turned out to be remarkably widespread (Huisgen, 1960, 1961). Because of easy 1,3-dipolar cycloaddition reactions to alkenes, alkynes, isocyanates, isothiocyanates, phospharanes, sulphenes and sulphynl compounds; nitrones are the important intermediates in synthetic organic chemistry (Black et al., 1975). There has been an ever-increasing quest for modified nucleosides, due to their potential applications in antiviral and anticancer therapies (Richman, 2001; De Clercq, 2002; Donadas et al., 2004). In a recent approach to modified nucleosides, the furanose ring has been replaced by other heterocyclic analogs (Merino et al., 2003). Among these N and O containing heterocycles have emerged as important candidates, and have been shown to display useful anticancer and antiviral properties (Chiacchio et al., 2003; Iannazzo et al., 2002). The present work is part of a structural study of compounds of substited 2,5-dimethyl-4-(thiophen-2-yl)-tetrahydropyrrolo[3,4 -c]pyrrole-1,\3(2H,3aH)-dione systems with hydrogen-bond donors, and we report herein the crystal structure of the title compound, (I).

The overall view and atom-labelling of the molecule of (I) are displayed in Fig. 1. The thiophene ring is oriented with respect to succinimide and phenyl rings at dihedral angles of 40.03 (12)° and 5.21 (13)°, respectively. The dihedral angle between succinimide and phenyl rings is 39.38 (12)°. The isoxazole ring has envelope conformation, with N1 atom displaced by -0.672 (2) Å from the plane of the other ring atoms.

The hydrogen-bonding parameters are given in Table 1 and the packing arrangements of the molecules are illustrated in Figs. 2 and 3. Compound is stabilized by intramolecular C—H···S hydrogen bond and S···N heteroatom interactions [in C1—S1···N; S···N = 3.033 (2) Å, C1—S1···N = 142.76 (9) °], which form S(4) and S(6) motifs, and intermolecular C—H···S and C—H···O hydrogen bonds and C—H···π interactions. As shown in Fig. 2 the structure of the compound is made up of C8—H8···S1 and C14—H14B···O2 H-bonded polymeric bands of [C12H14N2O3S] molecules, which are nearly elongated along [100]. These polymeric chains are linked to each other and generate R22(14) ring motifs (Bernstein et al., 1995; Etter, 1990). The crystal packing is also stabilized by C13—H13···Cg1 interactions (Fig. 3, Table 1).

Experimental

N-Methyl-C-(-5-Phenylthiophen) nitrone, (II), was prepared from 5-Phenylthiophenecarbaldehyde, N-methyl-hydroxylamine hydrochloride and sodium carbonate in CH2Cl2 according to the literature method (Heaney et al., 2001). For the preparation of the title compound, (II) (657 mg, 3 mmol) and N-methylmaleimide (370 mg, 3.3 mmol) were dissolved in benzene (50 ml). The reaction mixture was refluxed for 12 h, and monitored by TLC. After evaporation of the solvent, the reaction mixture was separated by column chromatography, using the mixture of petroleum ether/ethyl acetate (2:1) as the eluant. The cis-isomer, (I), was recrystallized from CHCl3/n-hexane (mp: 452,9-454,4 K).

Refinement

1451 Friedel pairs were averaged before the final refinement, but the absolute configuration could not be determined unambiguously, although Si atom is present. The methine H atoms, H11, H12 and H13, were located in difference syntheses and refined isotropically [C-H = 0.95 (3)-1.04 (3) Å; Uiso(H) = 0.035 (6)-0.071 (10) Å2]. The remaining H atoms were positioned geometrically, with C-H = 0.93 and 0.96 Å for aromatic and methyl H, respectively, and constrained to ride on their parent atoms with Uiso(H) = xUeq(C), where x = 1.5 for C14 methyl H and x = 1.2 for all other H atoms.

Figures

Fig. 1.
The molecular structure of the title molecule, with the atom-numbering scheme. Displacement ellipsoids are drawn at the 20% probability level. Hydrogen bonds are shown as dashed lines.
Fig. 2.
A partial packing diagram of (I), showing the formation of S(4), S(6) and R22(14) ring motifs along [100] [symmetry code: (i) x - 1/2, y, z]. Hydrogen bonds are shown as dashed lines. H atoms not involved in hydrogen bonding have been omitted for clarity. ...
Fig. 3.
A packing diagram of (I) [symmetry code: (i) 1 - x, 1 - y, -z], where Cg1 is the centroid of ring (S1/C7-C10). Hydrogen bonds are shown as dashed lines. H atoms not involved in hydrogen bonding have been omitted for clarity.

Crystal data

C17H16N2O3SF000 = 688
Mr = 328.38Dx = 1.400 Mg m3
Orthorhombic, Pna21Mo Kα radiation λ = 0.71073 Å
Hall symbol: P 2c -2nCell parameters from 6395 reflections
a = 12.7768 (7) Åθ = 1.8–28.0º
b = 10.9803 (6) ŵ = 0.22 mm1
c = 11.1069 (9) ÅT = 296 K
V = 1558.22 (17) Å3Prism, colorless
Z = 40.65 × 0.46 × 0.27 mm

Data collection

Stoe IPDSII diffractometer3332 independent reflections
Monochromator: plane graphite2899 reflections with I > 2σ(I)
Detector resolution: 6.67 pixels mm-1Rint = 0.051
T = 296 Kθmax = 27.5º
ω scan rotation methodθmin = 2.5º
Absorption correction: integration(X-RED32; Stoe & Cie, 2002)h = −13→16
Tmin = 0.889, Tmax = 0.935k = −13→14
6395 measured reflectionsl = −12→14

Refinement

Refinement on F2Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: fullH atoms treated by a mixture of independent and constrained refinement
R[F2 > 2σ(F2)] = 0.037  w = 1/[σ2(Fo2) + (0.0659P)2] where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.099(Δ/σ)max < 0.001
S = 1.04Δρmax = 0.22 e Å3
3332 reflectionsΔρmin = −0.22 e Å3
221 parametersExtinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
1 restraintExtinction coefficient: 0.0122 (17)
Primary atom site location: structure-invariant direct methodsAbsolute structure: Flack (1983)
Secondary atom site location: difference Fourier mapFlack parameter: −0.13 (8)

Special details

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 > 2sigma(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
C10.64659 (16)0.19809 (17)0.66560 (19)0.0427 (4)
C20.7443 (2)0.1782 (2)0.7188 (2)0.0585 (6)
H20.80480.19380.67490.070*
C30.7523 (2)0.1360 (3)0.8346 (3)0.0701 (7)
H30.81810.12270.86800.084*
C40.6641 (3)0.1132 (3)0.9022 (3)0.0721 (8)
H40.66960.08570.98110.087*
C50.5678 (2)0.1320 (3)0.8504 (2)0.0731 (8)
H50.50750.11630.89480.088*
C60.55911 (19)0.1738 (2)0.7341 (2)0.0593 (6)
H60.49300.18570.70110.071*
C70.63920 (16)0.24233 (18)0.5415 (2)0.0411 (4)
C80.71619 (15)0.2782 (2)0.4653 (3)0.0530 (5)
H80.78660.27890.48640.064*
C90.67952 (15)0.3144 (2)0.3508 (2)0.0511 (5)
H90.72360.33980.28910.061*
C100.57421 (14)0.30882 (18)0.33939 (19)0.0409 (4)
C110.50963 (15)0.3425 (2)0.23306 (19)0.0432 (4)
C120.46103 (16)0.4708 (2)0.22929 (19)0.0458 (4)
C130.36143 (17)0.4492 (2)0.15649 (19)0.0473 (5)
C140.4393 (2)0.1435 (2)0.1799 (2)0.0589 (6)
H14A0.37610.09630.17640.088*
H14B0.48840.10440.23270.088*
H14C0.46900.14980.10070.088*
C150.42400 (17)0.51840 (19)0.3496 (2)0.0490 (5)
C160.27329 (17)0.4855 (2)0.2411 (2)0.0506 (5)
C170.2543 (2)0.5584 (3)0.4516 (3)0.0716 (8)
H17A0.27080.64140.47110.086*
H17B0.27000.50720.51920.086*
H17C0.18120.55200.43260.086*
N10.41573 (13)0.26461 (15)0.22512 (15)0.0419 (4)
N20.31576 (15)0.52026 (17)0.34890 (18)0.0504 (4)
O10.47725 (15)0.55117 (17)0.43306 (17)0.0690 (5)
O20.18093 (14)0.48473 (19)0.2184 (2)0.0786 (6)
O30.35719 (12)0.32333 (14)0.12785 (14)0.0506 (4)
S10.51891 (3)0.25445 (5)0.47066 (6)0.04736 (14)
H110.5520 (18)0.3385 (19)0.161 (2)0.038 (5)*
H120.511 (2)0.535 (3)0.191 (3)0.068 (8)*
H130.356 (2)0.494 (3)0.079 (3)0.064 (8)*

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
C10.0437 (10)0.0377 (9)0.0468 (11)0.0072 (8)−0.0082 (8)−0.0047 (8)
C20.0489 (11)0.0677 (15)0.0590 (14)0.0064 (10)−0.0144 (11)0.0013 (11)
C30.0682 (16)0.0798 (17)0.0622 (16)0.0142 (13)−0.0284 (14)−0.0017 (13)
C40.085 (2)0.0832 (17)0.0478 (14)0.0131 (15)−0.0162 (13)0.0040 (12)
C50.0745 (18)0.096 (2)0.0489 (14)0.0006 (14)0.0033 (14)0.0095 (13)
C60.0491 (13)0.0780 (16)0.0508 (13)0.0091 (10)−0.0068 (10)0.0064 (11)
C70.0322 (9)0.0409 (9)0.0501 (12)0.0039 (8)−0.0056 (8)−0.0030 (7)
C80.0282 (8)0.0666 (13)0.0643 (13)0.0027 (8)−0.0018 (11)0.0054 (14)
C90.0299 (9)0.0670 (13)0.0564 (12)0.0011 (9)0.0055 (9)0.0079 (10)
C100.0305 (8)0.0497 (10)0.0426 (10)0.0005 (7)0.0039 (8)0.0012 (8)
C110.0339 (9)0.0595 (11)0.0361 (9)−0.0023 (8)0.0046 (8)0.0052 (8)
C120.0392 (9)0.0555 (11)0.0428 (10)−0.0083 (9)−0.0024 (8)0.0111 (9)
C130.0448 (10)0.0572 (11)0.0398 (11)−0.0034 (9)−0.0074 (8)0.0106 (8)
C140.0554 (13)0.0613 (13)0.0600 (14)0.0043 (10)−0.0034 (11)−0.0127 (10)
C150.0496 (11)0.0466 (10)0.0507 (11)0.0009 (9)−0.0084 (10)0.0050 (8)
C160.0437 (12)0.0522 (11)0.0559 (14)−0.0022 (8)−0.0037 (9)0.0045 (9)
C170.0770 (17)0.0676 (15)0.0704 (19)0.0072 (12)0.0215 (14)−0.0051 (13)
N10.0374 (8)0.0523 (9)0.0361 (8)−0.0025 (7)−0.0026 (6)−0.0002 (7)
N20.0497 (10)0.0516 (9)0.0499 (10)−0.0011 (8)0.0039 (9)0.0046 (7)
O10.0711 (12)0.0742 (11)0.0618 (11)0.0082 (9)−0.0242 (9)−0.0139 (9)
O20.0387 (9)0.0955 (13)0.1016 (16)0.0011 (8)−0.0111 (9)−0.0080 (12)
O30.0506 (9)0.0618 (9)0.0394 (7)−0.0024 (7)−0.0121 (6)0.0002 (6)
S10.0287 (2)0.0711 (3)0.0423 (2)−0.0033 (2)−0.0012 (2)0.0108 (2)

Geometric parameters (Å, °)

C1—C61.378 (3)C11—C121.540 (3)
C1—C21.398 (3)C11—H110.97 (2)
C1—C71.464 (3)C12—C151.511 (3)
C2—C31.371 (4)C12—C131.526 (3)
C2—H20.9300C12—H121.04 (3)
C3—C41.377 (5)C13—O31.419 (3)
C3—H30.9300C13—C161.520 (3)
C4—C51.374 (4)C13—H131.00 (3)
C4—H40.9300C14—N11.453 (3)
C5—C61.375 (4)C14—H14A0.9600
C5—H50.9300C14—H14B0.9600
C6—H60.9300C14—H14C0.9600
C7—C81.357 (3)C15—O11.205 (3)
C7—S11.732 (2)C15—N21.383 (3)
C8—C91.412 (4)C16—O21.207 (3)
C8—H80.9300C16—N21.369 (3)
C9—C101.353 (3)C17—N21.447 (3)
C9—H90.9300C17—H17A0.9600
C10—C111.487 (3)C17—H17B0.9600
C10—S11.727 (2)C17—H17C0.9600
C11—N11.476 (3)N1—O31.464 (2)
C6—C1—C2117.4 (2)C15—C12—C11114.73 (17)
C6—C1—C7122.11 (19)C13—C12—C11102.00 (17)
C2—C1—C7120.5 (2)C15—C12—H12108.7 (15)
C3—C2—C1121.1 (3)C13—C12—H12113.7 (15)
C3—C2—H2119.5C11—C12—H12112.3 (16)
C1—C2—H2119.5O3—C13—C16111.44 (18)
C2—C3—C4120.8 (2)O3—C13—C12107.59 (17)
C2—C3—H3119.6C16—C13—C12104.45 (18)
C4—C3—H3119.6O3—C13—H13106.8 (16)
C5—C4—C3118.5 (3)C16—C13—H13110.9 (17)
C5—C4—H4120.7C12—C13—H13115.7 (17)
C3—C4—H4120.7N1—C14—H14A109.5
C4—C5—C6121.0 (3)N1—C14—H14B109.5
C4—C5—H5119.5H14A—C14—H14B109.5
C6—C5—H5119.5N1—C14—H14C109.5
C5—C6—C1121.2 (2)H14A—C14—H14C109.5
C5—C6—H6119.4H14B—C14—H14C109.5
C1—C6—H6119.4O1—C15—N2124.4 (2)
C8—C7—C1129.6 (2)O1—C15—C12127.4 (2)
C8—C7—S1109.71 (17)N2—C15—C12108.27 (18)
C1—C7—S1120.70 (16)O2—C16—N2124.9 (2)
C7—C8—C9113.79 (18)O2—C16—C13126.4 (2)
C7—C8—H8123.1N2—C16—C13108.67 (18)
C9—C8—H8123.1N2—C17—H17A109.5
C10—C9—C8113.7 (2)N2—C17—H17B109.5
C10—C9—H9123.2H17A—C17—H17B109.5
C8—C9—H9123.2N2—C17—H17C109.5
C9—C10—C11127.94 (19)H17A—C17—H17C109.5
C9—C10—S1110.08 (16)H17B—C17—H17C109.5
C11—C10—S1121.97 (13)C14—N1—O3104.71 (16)
N1—C11—C10110.73 (16)C14—N1—C11112.49 (17)
N1—C11—C12101.59 (15)O3—N1—C11101.78 (14)
C10—C11—C12118.22 (18)C16—N2—C15113.39 (19)
N1—C11—H11112.3 (13)C16—N2—C17123.7 (2)
C10—C11—H11109.5 (14)C15—N2—C17122.9 (2)
C12—C11—H11104.2 (13)C13—O3—N1104.13 (14)
C15—C12—C13105.14 (18)C10—S1—C792.71 (10)
C6—C1—C2—C30.0 (3)C13—C12—C15—O1−177.3 (2)
C7—C1—C2—C3−179.6 (2)C11—C12—C15—O171.5 (3)
C1—C2—C3—C4−0.6 (4)C13—C12—C15—N21.9 (2)
C2—C3—C4—C50.9 (4)C11—C12—C15—N2−109.3 (2)
C3—C4—C5—C6−0.6 (5)O3—C13—C16—O2−65.7 (3)
C4—C5—C6—C10.0 (4)C12—C13—C16—O2178.4 (2)
C2—C1—C6—C50.3 (4)O3—C13—C16—N2114.50 (19)
C7—C1—C6—C5179.9 (2)C12—C13—C16—N2−1.4 (2)
C6—C1—C7—C8175.0 (2)C10—C11—N1—C14−76.4 (2)
C2—C1—C7—C8−5.4 (3)C12—C11—N1—C14157.21 (18)
C6—C1—C7—S1−5.3 (3)C10—C11—N1—O3172.10 (16)
C2—C1—C7—S1174.28 (17)C12—C11—N1—O345.68 (17)
C1—C7—C8—C9179.4 (2)O2—C16—N2—C15−177.0 (2)
S1—C7—C8—C9−0.4 (3)C13—C16—N2—C152.8 (3)
C7—C8—C9—C101.2 (3)O2—C16—N2—C171.5 (4)
C8—C9—C10—C11178.6 (2)C13—C16—N2—C17−178.8 (2)
C8—C9—C10—S1−1.4 (3)O1—C15—N2—C16176.2 (2)
C9—C10—C11—N1147.6 (2)C12—C15—N2—C16−3.0 (3)
S1—C10—C11—N1−32.4 (2)O1—C15—N2—C17−2.2 (4)
C9—C10—C11—C12−95.9 (3)C12—C15—N2—C17178.5 (2)
S1—C10—C11—C1284.2 (2)C16—C13—O3—N1−86.75 (19)
N1—C11—C12—C1584.5 (2)C12—C13—O3—N127.2 (2)
C10—C11—C12—C15−36.9 (3)C14—N1—O3—C13−163.37 (17)
N1—C11—C12—C13−28.59 (19)C11—N1—O3—C13−46.07 (19)
C10—C11—C12—C13−149.94 (17)C9—C10—S1—C71.06 (18)
C15—C12—C13—O3−118.85 (18)C11—C10—S1—C7−178.96 (17)
C11—C12—C13—O31.2 (2)C8—C7—S1—C10−0.40 (17)
C15—C12—C13—C16−0.3 (2)C1—C7—S1—C10179.86 (16)
C11—C12—C13—C16119.74 (18)

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
C6—H6···S10.932.693.100 (2)108
C8—H8···S1i0.933.003.887 (2)160
C14—H14B···O2i0.962.653.417 (4)137
C13—H13···Cg1ii1.00 (3)2.97 (3)3.876 (2)151 (2)

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

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: HK2484).

References

  • Bernstein, J., Davis, R. E., Shimoni, L. & Chang, N.-L. (1995). Angew. Chem. Int. Ed. Engl.34, 1555–1573.
  • Black, D. C., Crozier, R. F. & Davis, V. C. (1975). Synthesis, pp. 205–221.
  • Chiacchio, U., Corsaro, A., Iannazzo, D., Piperno, A., Pistara, V., Rescifina, A., Romeo, R., Sindona, G. & Romeo, G. (2003). Tetrahedron Asymmetry, 14, 2717–2723.
  • De Clercq, E. (2002). Nat. Rev. Drug Discov.1, 13–26. [PubMed]
  • Donadas, H. A., Fishwick, C. W. G., Grigg, R. & Kilner, C. (2004). Tetrahedron, 60, 3473–3485.
  • Etter, M. C. (1990). Acc. Chem. Res.23, 120–126.
  • Farrugia, L. J. (1997). J. Appl. Cryst.30, 565.
  • Farrugia, L. J. (1999). J. Appl. Cryst.32, 837–838.
  • Flack, H. D. (1983). Acta Cryst. A39, 876–881.
  • Heaney, F., Rooney, O., Cunningham, D. & McArdle, P. (2001). J. Chem. Soc. Perkin Trans. 2, pp. 373–378.
  • Huisgen, R. (1960). 10 Jahre Fonds der Chemischen Industrie Düsseldorf, p. 73; reprinted in Naturwissenschaften (1961), 4, 63.
  • Iannazzo, D., Piperno, A., Pistara, V., Rescifina, A. & Romeo, R. (2002). Tetrahedron, 58, 581–587.
  • Merino, P., Tejero, T., Laguna, M., Cerrada, E., Moreno, A. & Lopez, J. A. (2003). Org. Biomol. Chem.1, 2336–2342. [PubMed]
  • Richman, D. D. (2001). Nature (London), 410, 995–1001. [PubMed]
  • Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. [PubMed]
  • Stoe & Cie (2002). X-AREA and X-RED32 Stoe & Cie, Darmstadt, Germany.

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