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

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890
Volume 68| Part 12| December 2012| Page o3496
doi:10.1107/S1600536812048519

(3aRS,7aSR)-7a-Meth­­oxy-2-oxo-2,3,3a,4,5,6,7,7a-octa­hydro-1-benzo­furan-4,4-dicarbo­nitrile

María González,a* Andrea Martínez,a Marcos L. Rivadullaa and Berta Covelob

aDpto. Química Orgánica, Facultade de Química, Universidade de Vigo, E-36310 Vigo, Spain, and bUnidad de Difracción de Raios X de Monocristal, Servicio Determinación Estructural, Proteómica e Xenómica, CACTI-Universidade de Vigo, E-36310 Vigo, Spain
*Correspondence e-mail: magonpe@uvigo.es

(Received 6 November 2012; accepted 26 November 2012; online 30 November 2012)

The racemic title compound, C11H12N2O3, contains a [4.3.0]bicyclic unit in which the shared C—C bond adopts a cis configuration. The five- and six-membered rings are in twisted envelope (with the bridgehead C atom bearing the methoxy substituent as the flap) and distorted chair conformations, respectively. In the crystal, the mol­ecules are linked via weak C—H⋯O iteractions, forming ladder-like chains along [010].

Related literature

For related syntheses of natural products, see: Jones & Goodbrand (1977[Jones, J. B. & Goodbrand, H. B. (1977). Can. J. Chem. 55, 2685-2691.]). For details of a synthesis using different starting materials, see: Alonso et al. (2005[Alonso, D., Pérez, M., Gómez, G., Covelo, B. & Fall, Y. (2005). Tetrahedron, 61, 2021-2026.]); Pérez et al. (2004[Pérez, M., Canoa, P., Gómez, G., Terán, C. & Fall, Y. (2004). Tetrahedron Lett. 45, 5207-5209.], 2005[Pérez, M., Canoa, P., Gómez, G., Teijeira, M. & Fall, Y. (2005). Synthesis, pp. 411-414.]). For a related structure, see: Grudniewska et al. (2011[Grudniewska, A., Dancewicz, K., Bialońska, A., Ciunik, Z., Gabrýs, B. & Wawrzeńczyk, C. (2011). Advances, 1, 498-510.]). For puckering parameters, see, Cremer & Pople (1975[Cremer, D. & Pople, J. A. (1975). J. Am. Chem. Soc. 97, 1354-1358.]).

[Scheme 1]

Experimental

Crystal data

  • C11H12N2O3

  • Mr = 220.23

  • Monoclinic, P 21 /n

  • a = 11.816 (3) Å

  • b = 7.228 (2) Å

  • c = 13.017 (4) Å

  • β = 104.250 (5)°

  • V = 1077.6 (5) Å3

  • Z = 4

  • Mo Kα radiation

  • μ = 0.10 mm−1

  • T = 293 K

  • 0.49 × 0.24 × 0.19 mm
Data collection

  • Bruker SMART 1000 CCD diffractometer

  • Absorption correction: multi-scan (SADABS; Sheldrick, 1996[Sheldrick, G. M. (1996). SADABS. University of Göttingen, Germany.]) Tmin = 0.697, Tmax = 0.745

  • 5473 measured reflections

  • 1893 independent reflections

  • 1244 reflections with I > 2σ(I)

  • Rint = 0.030
Refinement

  • R[F2 > 2σ(F2)] = 0.048

  • wR(F2) = 0.143

  • S = 1.03

  • 1893 reflections

  • 146 parameters

  • H-atom parameters constrained

  • Δρmax = 0.45 e Å−3

  • Δρmin = −0.19 e Å−3

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A D⋯A D—H⋯A
C3—H3A⋯O3i 0.97 2.59 3.290 (3) 129
C8—H8C⋯O2ii 0.96 2.46 3.219 (4) 136
Symmetry codes: (i) -x+1, -y+2, -z+1; (ii) x, y+1, z.

Data collection: SMART (Bruker, 1998[Bruker (1998). SMART and SAINT. Bruker AXS Inc., Madinson, Wisconsin, USA.]); cell refinement: SAINT (Bruker, 1998[Bruker (1998). SMART and SAINT. Bruker AXS Inc., Madinson, Wisconsin, USA.]); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); molecular graphics: PLATON (Spek, 2011)[Spek, A. L. (2009). Acta Cryst. D65, 148-155.] and Mercury (Macrae et al., 2006[Macrae, C. F., Edgington, P. R., McCabe, P., Pidcock, E., Shields, G. P., Taylor, R., Towler, M. & van de Streek, J. (2006). J. Appl. Cryst. 39, 453-457.]); software used to prepare material for publication: SHELXTL (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]).

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536812048519/jj2158sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536812048519/jj2158Isup2.hkl

Supporting information file. DOI: 10.1107/S1600536812048519/jj2158Isup3.cml

checkCIF report


Comment top

The racemic title compound is a [4.3.0] bicyclic γ-lactone obtained through an intramolecular Michael addition. The construction of carbocyclic systems is of paramount importance in organic synthesis since they are intermediate compounds for the preparation of interesting natural products (Jones et al., 1977) as carbocyclic nucleosides and vitamin D analogues. We have described a new methodology for the synthesis of oxacyclic compounds using either methoxyallene (Alonso et al., 2005) or furan (Pérez et al., 2005) as a starting material. In the title compound (Fig. 1), the C—C share bond of the bicyclic moiety adopts a cis configuration. The 5-membered ring adopts a twisted envelope conformation with puckering parameters Q = 0.358 (2) Å and ϕ = 126.7 (4)° (Cremer & Pople, 1975) and the 6-membered ring adopts a distorted chair conformation with puckering parameters Q = 0.531 (3) Å, θ = 19.3 (3)° and ϕ = 123.3 (9)° (Cremer & Pople (1975). All bond lengths and bond angles are normal comparable to those observed in similar crystal structures (Grudniewska et al., 2011). In the crystal structure, the molecules are self-assembled via weak C—H···O intermolecular interactions (Table 1) to form a ladderlike chain structure along [010] (Fig. 2).

Related literature top

For related syntheses of natural products, see: Jones & Goodbrand (1977). For details of a synthesis using different starting materials, see: Alonso et al. (2005); Pérez et al. (2004, 2005). For a related structure, see: Grudniewska et al. (2011). For puckering parameters, see, Cremer & Pople (19750.

Experimental top

To a solution of 2-(3-(2-methoxy-5-oxo-2,5-dihydrofuran-2-yl)propyl)malononitrile (0.38 mmol) in DMF (3 ml) was added DBU (0.19 mmol, 0.5 eq) and the mixture was stirred at room temperature. At the end of the reaction (TLC), EtOAc (20 ml) was added and the organic layers washed with water (3 x 20 ml), dried (Na2SO4), filtered, and concentrated to afford a residue, which was chromatographed on silica gel giving the title compound. It was then recrystallized using EtOAc/Hexane.

Refinement top

All H atoms were positioned geometrically and refined using a riding model with C—H = 0.96–0.98 Å and Uiso(H) = 1.2Ueq(C) or 1.5 Ueq(Cmethyl).

Computing details top

Data collection: SMART (Bruker, 1998); cell refinement: SAINT (Bruker, 1998); data reduction: SAINT (Bruker, 1998); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2011) and Mercury (Macrae et al., 2006); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. The molecular structure of the title compound. Non-H atoms are present as displacement ellipsoids at the 30% probability level.
[Figure 2] Fig. 2. The crystal structure of the title compound. Weak C—H···O intermolecular interactions link the molecules into chains along [001]. H atoms not involved in hydrogen bonds (dashed lines) have been omitted for clarity.
(3aRS,7aSR)-7a-Methoxy-2-oxo-2,3,3a,4,5,6,7,7a-octahydro- 1-benzofuran-4,4-dicarbonitrile top
Crystal data top
C11H12N2O3F(000) = 464
Mr = 220.23Dx = 1.357 Mg m−3
Monoclinic, P21/nMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ynCell parameters from 1285 reflections
a = 11.816 (3) Åθ = 2.7–22.8°
b = 7.228 (2) ŵ = 0.10 mm−1
c = 13.017 (4) ÅT = 293 K
β = 104.250 (5)°Prism, colourless
V = 1077.6 (5) Å30.49 × 0.24 × 0.19 mm
Z = 4
Data collection top
Bruker SMART 1000 CCD
diffractometer		1893 independent reflections
Radiation source: fine-focus sealed tube1244 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.030
ϕ and ω scansθmax = 25.0°, θmin = 2.1°
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)		h = −13→14
Tmin = 0.697, Tmax = 0.745k = −8→8
5473 measured reflectionsl = −14→15
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)] = 0.048Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.143H-atom parameters constrained
S = 1.03 w = 1/[σ2(Fo2) + (0.0722P)2 + 0.3369P]
where P = (Fo2 + 2Fc2)/3
1893 reflections(Δ/σ)max < 0.001
146 parametersΔρmax = 0.45 e Å−3
0 restraintsΔρmin = −0.19 e Å−3
Crystal data top
C11H12N2O3V = 1077.6 (5) Å3
Mr = 220.23Z = 4
Monoclinic, P21/nMo Kα radiation
a = 11.816 (3) ŵ = 0.10 mm−1
b = 7.228 (2) ÅT = 293 K
c = 13.017 (4) Å0.49 × 0.24 × 0.19 mm
β = 104.250 (5)°
Data collection top
Bruker SMART 1000 CCD
diffractometer		1893 independent reflections
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)		1244 reflections with I > 2σ(I)
Tmin = 0.697, Tmax = 0.745Rint = 0.030
5473 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0480 restraints
wR(F2) = 0.143H-atom parameters constrained
S = 1.03Δρmax = 0.45 e Å−3
1893 reflectionsΔρmin = −0.19 e Å−3
146 parameters
Special details top

Experimental. [mp: 175–177 °C; IR (neat): 2248, 1800, 1744 cm-1; 1H NMR (CDCl3): δ: 3.38 (3H, s, OMe); 3.21 (1H, dd, J = 7.60, 17.78); 2.86 (1H, dd, J = 3.53, 7.60); 2.70 (1H, dd, J = 3.53, 17.78); 2.39–2.33 (2H, m); 2.16–1.80 (4H, m); 13C NMR (CDCl3): δ: 171.69 (C=O); 114.67 (CN); 112.89 (CN); 105.51 (C); 50.05 (OMe); 45.74 (CH); 35.79 (CH2); 33.59 (CH2); 31.89 (CH2); 28.56 (CH2); 17.68 (CH2); HRMS: calcd for C11H13N2O3 [M+1H]+ 221.0926, found 221.0583].

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
O10.67913 (13)0.7856 (2)0.36232 (13)0.0423 (5)
O20.67361 (18)0.5064 (3)0.43402 (17)0.0660 (6)
O30.63413 (13)1.0294 (2)0.45900 (12)0.0401 (4)
N410.2043 (2)0.7955 (4)0.1943 (2)0.0671 (7)
N420.5146 (2)0.5424 (4)0.1555 (2)0.0700 (8)
C20.6249 (2)0.6485 (4)0.4044 (2)0.0454 (6)
C30.5029 (2)0.7069 (3)0.40461 (19)0.0415 (6)
H3A0.49610.73180.47610.050*
H3B0.44670.61250.37310.050*
C3A0.48499 (18)0.8826 (3)0.33778 (17)0.0344 (6)
H30.43710.97080.36580.041*
C40.42864 (19)0.8445 (3)0.21834 (18)0.0394 (6)
C50.4493 (2)1.0080 (4)0.14904 (19)0.0464 (7)
H5A0.41190.98280.07530.056*
H5B0.41501.11950.16980.056*
C60.5794 (2)1.0369 (4)0.1619 (2)0.0508 (7)
H6A0.59161.13600.11550.061*
H6B0.61370.92500.14150.061*
C70.6392 (2)1.0854 (4)0.27642 (19)0.0453 (6)
H7A0.72301.08560.28450.054*
H7B0.61641.20970.29110.054*
C7A0.61086 (19)0.9552 (3)0.35683 (18)0.0352 (6)
C80.7522 (2)1.0884 (4)0.5017 (2)0.0520 (7)
H8A0.80480.99390.49020.078*
H8B0.76451.11050.57640.078*
H8C0.76621.20040.46720.078*
C420.4769 (2)0.6739 (4)0.1824 (2)0.0483 (7)
C410.3020 (2)0.8146 (4)0.2047 (2)0.0460 (6)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O10.0349 (9)0.0400 (10)0.0545 (10)0.0055 (7)0.0155 (8)−0.0029 (8)
O20.0677 (13)0.0411 (12)0.0881 (16)0.0172 (10)0.0173 (11)0.0123 (10)
O30.0359 (9)0.0462 (10)0.0375 (9)−0.0036 (7)0.0078 (7)−0.0089 (7)
N410.0405 (14)0.086 (2)0.0718 (17)−0.0063 (13)0.0091 (12)−0.0035 (14)
N420.0580 (16)0.0740 (19)0.0745 (18)0.0034 (14)0.0096 (13)−0.0302 (15)
C20.0500 (15)0.0367 (15)0.0489 (15)0.0027 (12)0.0113 (12)−0.0013 (12)
C30.0409 (14)0.0411 (14)0.0440 (14)−0.0036 (11)0.0133 (11)−0.0006 (12)
C3A0.0316 (12)0.0379 (13)0.0357 (13)0.0007 (10)0.0122 (10)−0.0021 (10)
C40.0320 (12)0.0472 (15)0.0388 (13)0.0008 (10)0.0080 (10)−0.0043 (11)
C50.0462 (15)0.0574 (17)0.0358 (14)0.0016 (12)0.0102 (11)0.0048 (11)
C60.0494 (16)0.0640 (19)0.0424 (15)−0.0038 (13)0.0177 (12)0.0042 (13)
C70.0438 (14)0.0470 (15)0.0468 (15)−0.0060 (12)0.0146 (11)0.0027 (12)
C7A0.0330 (12)0.0357 (13)0.0384 (13)0.0012 (10)0.0113 (10)−0.0041 (10)
C80.0449 (15)0.0523 (16)0.0527 (16)−0.0055 (13)0.0003 (12)−0.0030 (13)
C420.0392 (14)0.0572 (18)0.0473 (15)−0.0049 (13)0.0081 (12)−0.0164 (14)
C410.0390 (15)0.0535 (17)0.0446 (15)−0.0012 (12)0.0086 (11)−0.0042 (12)
Geometric parameters (Å, º) top
O1—C21.366 (3)C4—C421.482 (4)
O1—C7A1.460 (3)C4—C51.542 (3)
O2—C21.194 (3)C5—C61.519 (4)
O3—C7A1.397 (3)C5—H5A0.9700
O3—C81.433 (3)C5—H5B0.9700
N41—C411.137 (3)C6—C71.525 (4)
N42—C421.141 (3)C6—H6A0.9700
C2—C31.503 (3)C6—H6B0.9700
C3—C3A1.524 (3)C7—C7A1.505 (3)
C3—H3A0.9700C7—H7A0.9700
C3—H3B0.9700C7—H7B0.9700
C3A—C7A1.539 (3)C8—H8A0.9600
C3A—C41.558 (3)C8—H8B0.9600
C3A—H30.9800C8—H8C0.9600
C4—C411.479 (3)
C2—O1—C7A108.73 (17)H5A—C5—H5B108.2
C7A—O3—C8115.36 (17)C5—C6—C7110.6 (2)
O2—C2—O1121.2 (2)C5—C6—H6A109.5
O2—C2—C3128.8 (2)C7—C6—H6A109.5
O1—C2—C3110.0 (2)C5—C6—H6B109.5
C2—C3—C3A103.38 (18)C7—C6—H6B109.5
C2—C3—H3A111.1H6A—C6—H6B108.1
C3A—C3—H3A111.1C7A—C7—C6114.0 (2)
C2—C3—H3B111.1C7A—C7—H7A108.7
C3A—C3—H3B111.1C6—C7—H7A108.7
H3A—C3—H3B109.1C7A—C7—H7B108.7
C3—C3A—C7A101.50 (17)C6—C7—H7B108.7
C3—C3A—C4112.80 (19)H7A—C7—H7B107.6
C7A—C3A—C4112.33 (17)O3—C7A—O1107.39 (18)
C3—C3A—H3110.0O3—C7A—C7113.4 (2)
C7A—C3A—H3110.0O1—C7A—C7110.14 (18)
C4—C3A—H3110.0O3—C7A—C3A103.91 (17)
C41—C4—C42107.3 (2)O1—C7A—C3A102.82 (18)
C41—C4—C5110.1 (2)C7—C7A—C3A118.23 (19)
C42—C4—C5108.9 (2)O3—C8—H8A109.5
C41—C4—C3A108.48 (18)O3—C8—H8B109.5
C42—C4—C3A111.02 (19)H8A—C8—H8B109.5
C5—C4—C3A110.99 (19)O3—C8—H8C109.5
C6—C5—C4110.0 (2)H8A—C8—H8C109.5
C6—C5—H5A109.7H8B—C8—H8C109.5
C4—C5—H5A109.7N42—C42—C4179.5 (3)
C6—C5—H5B109.7N41—C41—C4178.6 (3)
C4—C5—H5B109.7
C7A—O1—C2—O2−166.8 (2)C8—O3—C7A—C3A173.04 (19)
C7A—O1—C2—C313.8 (3)C2—O1—C7A—O377.4 (2)
O2—C2—C3—C3A−169.1 (3)C2—O1—C7A—C7−158.74 (19)
O1—C2—C3—C3A10.3 (3)C2—O1—C7A—C3A−31.9 (2)
C2—C3—C3A—C7A−28.3 (2)C6—C7—C7A—O3−160.9 (2)
C2—C3—C3A—C492.2 (2)C6—C7—C7A—O178.7 (2)
C3—C3A—C4—C4178.0 (2)C6—C7—C7A—C3A−39.0 (3)
C7A—C3A—C4—C41−168.0 (2)C3—C3A—C7A—O3−75.5 (2)
C3—C3A—C4—C42−39.6 (2)C4—C3A—C7A—O3163.78 (18)
C7A—C3A—C4—C4274.3 (2)C3—C3A—C7A—O136.4 (2)
C3—C3A—C4—C5−160.97 (18)C4—C3A—C7A—O1−84.4 (2)
C7A—C3A—C4—C5−47.0 (3)C3—C3A—C7A—C7157.9 (2)
C41—C4—C5—C6−179.2 (2)C4—C3A—C7A—C737.2 (3)
C42—C4—C5—C6−61.8 (3)C41—C4—C42—N42−121 (39)
C3A—C4—C5—C660.7 (3)C5—C4—C42—N42120 (39)
C4—C5—C6—C7−61.9 (3)C3A—C4—C42—N42−3 (40)
C5—C6—C7—C7A50.4 (3)C42—C4—C41—N41−160 (11)
C8—O3—C7A—O164.6 (2)C5—C4—C41—N41−42 (11)
C8—O3—C7A—C7−57.3 (3)C3A—C4—C41—N4180 (11)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C3—H3A···O3i0.972.593.290 (3)129
C8—H8C···O2ii0.962.463.219 (4)136
Symmetry codes: (i) −x+1, −y+2, −z+1; (ii) x, y+1, z.

Experimental details

Crystal data
Chemical formulaC11H12N2O3
Mr220.23
Crystal system, space groupMonoclinic, P21/n
Temperature (K)293
a, b, c (Å)11.816 (3), 7.228 (2), 13.017 (4)
β (°) 104.250 (5)
V (Å3)1077.6 (5)
Z4
Radiation typeMo Kα
µ (mm−1)0.10
Crystal size (mm)0.49 × 0.24 × 0.19
Data collection
DiffractometerBruker SMART 1000 CCD
diffractometer
Absorption correctionMulti-scan
(SADABS; Sheldrick, 1996)
Tmin, Tmax0.697, 0.745
No. of measured, independent and
observed [I > 2σ(I)] reflections		5473, 1893, 1244
Rint0.030
(sin θ/λ)max (Å−1)0.595
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.048, 0.143, 1.03
No. of reflections1893
No. of parameters146
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å−3)0.45, −0.19

Computer programs: SMART (Bruker, 1998), SAINT (Bruker, 1998), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), PLATON (Spek, 2011) and Mercury (Macrae et al., 2006), SHELXTL (Sheldrick, 2008).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C3—H3A···O3i0.972.593.290 (3)129.3
C8—H8C···O2ii0.962.463.219 (4)136.0
Symmetry codes: (i) −x+1, −y+2, −z+1; (ii) x, y+1, z.
 

Acknowledgements

This work was supported financially by the Spanish Ministry of Foreign Affairs and Cooperation (PCIA/030052/10) and the Xunta de Galicia (INCITE845B-2010/020, INCITE08PXIB314255PR).

References

First citationAlonso, D., Pérez, M., Gómez, G., Covelo, B. & Fall, Y. (2005). Tetrahedron, 61, 2021–2026.  Web of Science CSD CrossRef CAS Google Scholar
 First citationBruker (1998). SMART and SAINT. Bruker AXS Inc., Madinson, Wisconsin, USA.  Google Scholar
 First citationCremer, D. & Pople, J. A. (1975). J. Am. Chem. Soc. 97, 1354–1358.  CrossRef CAS Web of Science Google Scholar
 First citationGrudniewska, A., Dancewicz, K., Bialońska, A., Ciunik, Z., Gabrýs, B. & Wawrzeńczyk, C. (2011). Advances, 1, 498–510.  CAS Google Scholar
 First citationJones, J. B. & Goodbrand, H. B. (1977). Can. J. Chem. 55, 2685–2691.  CrossRef CAS Web of Science Google Scholar
 First citationMacrae, C. F., Edgington, P. R., McCabe, P., Pidcock, E., Shields, G. P., Taylor, R., Towler, M. & van de Streek, J. (2006). J. Appl. Cryst. 39, 453–457.  Web of Science CrossRef CAS IUCr Journals Google Scholar
 First citationPérez, M., Canoa, P., Gómez, G., Teijeira, M. & Fall, Y. (2005). Synthesis, pp. 411–414.  Google Scholar
 First citationPérez, M., Canoa, P., Gómez, G., Terán, C. & Fall, Y. (2004). Tetrahedron Lett. 45, 5207–5209.  Google Scholar
 First citationSheldrick, G. M. (1996). SADABS. University of Göttingen, Germany.  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

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ISSN: 2056-9890
Volume 68| Part 12| December 2012| Page o3496
doi:10.1107/S1600536812048519
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