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Acta Crystallogr Sect E Struct Rep Online. 2010 February 1; 66(Pt 2): o422–o423.
Published online 2010 January 23. doi:  10.1107/S1600536810001984
PMCID: PMC2979692

N,N′-Bis­[(E)-2-fluoro­benzyl­idene]-1-(2-fluoro­phen­yl)methane­diamine

Abstract

In the title compound, C21H15F3N2, the benzene ring bonded to the central C atom forms dihedral angles of 77.5 (7) and 89.0 (5)°, respectively, with the remaining two benzene rings. Weak inter­molecular C—H(...)F hydrogen bonds link the mol­ecules into chains propagated in [101]. The crystal packing exhibits weak π–π inter­actions as evidenced by relatively short distances between the centroids of the aromatic rings [3.820 (7) and 3.971 (5) Å]. A MOPAC PM3 optimization of the mol­ecular geometry in vacuo supports a suggestion that inter­molecular forces have a significnt influence on the mol­ecular conformation in the crystal.

Related literature

For aromatic aldehyde reactions, see Williams & Bailar (1959 [triangle]). For kinetics of hydro­benzamides, see Crampton et al. (1997 [triangle]). For conventional preparation of hydro­benzamides, see Kamal & Qureshi (1963 [triangle]). For related structures, see: Corey & Kuhnle (1997 [triangle]); Karupaiyan et al. (1998 [triangle]); Saigo et al. (1986 [triangle]). For bond-length data, see: Allen et al. (1987 [triangle]). For the synthesis of nitro­gen-containing heterocyclic compounds, see Kupfer & Brinker (1996 [triangle]). For MOPAC PM3 calculations, see Schmidt & Polik (2007 [triangle]).

An external file that holds a picture, illustration, etc.
Object name is e-66-0o422-scheme1.jpg

Experimental

Crystal data

  • C21H15F3N2
  • M r = 352.35
  • Triclinic, An external file that holds a picture, illustration, etc.
Object name is e-66-0o422-efi1.jpg
  • a = 8.0215 (5) Å
  • b = 9.3740 (4) Å
  • c = 11.9744 (6) Å
  • α = 99.184 (4)°
  • β = 93.179 (5)°
  • γ = 108.165 (5)°
  • V = 839.23 (8) Å3
  • Z = 2
  • Mo Kα radiation
  • μ = 0.11 mm−1
  • T = 200 K
  • 0.49 × 0.29 × 0.22 mm

Data collection

  • Oxford Diffraction Gemini diffractometer
  • 11550 measured reflections
  • 5484 independent reflections
  • 3292 reflections with I > 2σ(I)
  • R int = 0.025

Refinement

  • R[F 2 > 2σ(F 2)] = 0.052
  • wR(F 2) = 0.152
  • S = 1.00
  • 5484 reflections
  • 235 parameters
  • H-atom parameters constrained
  • Δρmax = 0.57 e Å−3
  • Δρmin = −0.20 e Å−3

Data collection: CrysAlis PRO (Oxford Diffraction, 2007 [triangle]); cell refinement: CrysAlis PRO; data reduction: CrysAlis PRO; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 [triangle]); molecular graphics: SHELXTL (Sheldrick, 2008 [triangle]); software used to prepare material for publication: SHELXTL.

Table 1
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536810001984/cv2683sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810001984/cv2683Isup2.hkl

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

Acknowledgments

QNMHA thanks the University of Mysore for use of their research facilities. RJB acknowledges the NSF MRI program (grant No. CHE-0619278) for funds to purchase an X-ray diffractometer.

supplementary crystallographic information

Comment

Reaction of aromatic aldehydes with ammonia leads to the long-known compounds called "hydrobenzamides" (Williams & Bailar, 1959). Owing to their unique structural features and reactivity, these compounds have been recognized as potential key intermediates for the synthesis of a variety of nitrogen containing heterocyclic compounds (Kupfer & Brinker, 1996). Extensive studies on kinetics and mechanism of formation of hydrobenzamides from aromatic aldehydes and ammonia have been well documented (Crampton et al. 1997). The only conventional method available for the preparation of these compounds involves the reaction of aldehydes with ammonia, a complex reversible reaction which takes days to weeks for completion (Kamal & Qureshi, 1963). Moreover, protic solvents used in this reaction such as methanol or water enhance the reversible conversion of products into starting aldehydes, thereby reducing the yields even after longer reaction times. Due to the importance of these compounds, we report the crystal structure of a newly synthesized derivative, C21H15F3N2, (I).

The title compound, C21H15F3N2, (I), consists of a 2-fluorophenyl group and a N,N'-bis[(E)-(2-fluorophenyl)methylidene]methanediamine group bonded to a methane carbon, C1 (Fig. 1). The benzene ring bonded to the central methyl carbon atom forms dihedral angles of 77.5 (7)° and 89.0 (5)°, respectively, with the remaining two benzene rings. The dihedral angle between the mean planes of the remaining two benzene rings is 15.7 (7)°. Five of the angles around the methane carbon, C1, are in the vicinity of the 108°-109° range (N1A—C1—C2; 109.45 (11)°, N1B—C1—C2; 108.04 (10)°, C2—C1—H1A; 108.(2)°, N1A—C1—H1A; 108.(2)°, N1B—C1—H1A; 108.(2)°) with only the N1A—C1—N2A angle measuring 114.48 (10)° giving it a slightly distorted sp3 configuration in the direction of the two nitrogen atoms. Bond lengths and bond angles are all within expected ranges (Allen et al., 1987).

Crystal packing is influenced by weak C—H···F intermolecular hydrogen bond interactions which link the molecule into chains propagating obliquely along the c axis in the direction [101] (Fig. 2). In addition, weak Cg2···Cg2 (3.971 (5) Å; -x, 1 - y, -z) and Cg3···Cg3 (3.820 (7) Å; 2 - x, 2 - y, 1 - z) π-π intermolecular interactions are observed with slippage distances of 1.81 (4) Å and 1.76 (5) Å, respectively. (Cg2, Cg3 = ring centroids for C2A—C7A and C2B—C7B, respectively).

In support of these observations, a MOPAC PM3 calculation was performed on the C21H15F3N2, molecule with WebMO Pro (Schmidt & Polik, 2007) (PM3, Parameterized Model 3) approximation together with the Hartree-Fock closed-shell (restricted) wavefunction was used and minimizations were teminnated at an r.m.s. gradient of less than 0.01 kJ mol-1 Å-1.). While the bond distances did not appear to change significantly, selected bond and torsion angles were noticeably different. The bond angle for N1A—C1A—N1B (114.48 (10)° versus 111.3°) is shorter and for C2A—C3A—F1A (117.81 (12)° versus 120.4°) is wider after the calculation. The torsion angles for C1A—N1A—C1—C2 (86.45 (14)° versus 78.17°) and C1B—N1B—C1—C2 (124.39 (13)° versus 96.35°) are both much lower after the calculation indicating a much greater twist causing the two benzene rings to be further apart. This is supported by the PM3 calculated value of 36.79° (versus. 15.7 (7)° before the calculation) for the angle between the mean planes of the two benzene rings. In addition the angles between the mean planes of the two benzene rings with the C1 bonded benzene are 70.22° (versus.77.5 (7)°) and 82.32° (versus. 89.0 (5)°), respectively, after the calculation. This suggests that small changes in some bond distances and selectively in some bond and torsion angles, especially involving the diamine nitrogen atoms have been infuenced by the collective effect of all of the weak intermolecular interactions that have been observed in the crystal packing.

Experimental

10 ml of 25% methanolic ammonia was added to a solution of 2 g of 2-flurobenzaldehyde in 10 ml me thanol and left to stand at ambient temperature for 2 days, during which the crystalline products separated out (Fig. 3). The crude crystals were filtered off, washed with cold methanol. Good quality x-ray grade crystals were obtained by the slow evaporation of the solution in ethyl acetate (m.p.: 425–427 K). Analysis for the title compound C21H15F3N2: Found (calculated): C: 71.75 (71.82); H: 4.26 (4.29); N: 7.90 (7.95).

Refinement

All of the H atoms were placed in their calculated positions and then refined using the riding model with C—H = 0.95 Å, and with Uiso(H) = 1.18–1.20Ueq(C).

Figures

Fig. 1.
Molecular structure of (I), C21H15F3N2, showing the atom labeling scheme and 50% probability displacement ellipsoids.
Fig. 2.
The molecular packing for (I) viewed down the b axis. Dashed lines indicate weak C—H···F intermolecular hydrogen bond interactions which link the molecule into chains propagating obliquely along the c axis.
Fig. 3.
Synthetic scheme for C21H15F3N2, (I).

Crystal data

C21H15F3N2Z = 2
Mr = 352.35F(000) = 364
Triclinic, P1Dx = 1.394 Mg m3
Hall symbol: -P 1Mo Kα radiation, λ = 0.71073 Å
a = 8.0215 (5) ÅCell parameters from 4026 reflections
b = 9.3740 (4) Åθ = 4.6–32.4°
c = 11.9744 (6) ŵ = 0.11 mm1
α = 99.184 (4)°T = 200 K
β = 93.179 (5)°Prism, colourless
γ = 108.165 (5)°0.49 × 0.29 × 0.22 mm
V = 839.23 (8) Å3

Data collection

Oxford Diffraction Gemini diffractometer3292 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.025
graphiteθmax = 32.5°, θmin = 4.6°
Detector resolution: 10.5081 pixels mm-1h = −11→12
[var phi] and ω scansk = −14→13
11550 measured reflectionsl = −16→17
5484 independent reflections

Refinement

Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.052Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.152H-atom parameters constrained
S = 1.00w = 1/[σ2(Fo2) + (0.0841P)2] where P = (Fo2 + 2Fc2)/3
5484 reflections(Δ/σ)max < 0.001
235 parametersΔρmax = 0.57 e Å3
0 restraintsΔρmin = −0.20 e Å3

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
F10.62912 (14)1.01485 (11)0.09363 (8)0.0596 (3)
F1A0.21867 (14)0.54600 (10)−0.14842 (7)0.0511 (3)
F1B0.62463 (12)0.41513 (8)0.48075 (7)0.0434 (2)
N1A0.43939 (15)0.62936 (12)0.17778 (9)0.0315 (3)
N1B0.70316 (15)0.77388 (12)0.31351 (9)0.0314 (3)
C10.58583 (18)0.77356 (14)0.21571 (11)0.0297 (3)
H1A0.65760.79410.15090.036*
C20.51189 (17)0.90345 (13)0.24663 (10)0.0282 (3)
C30.53477 (19)1.01805 (15)0.18400 (11)0.0344 (3)
C40.4682 (2)1.13682 (16)0.20930 (13)0.0424 (4)
H4A0.48711.21370.16400.051*
C50.3733 (2)1.14203 (16)0.30200 (13)0.0427 (4)
H5A0.32491.22220.32030.051*
C60.3491 (2)1.03019 (16)0.36807 (12)0.0404 (3)
H6A0.28551.03450.43240.049*
C70.4174 (2)0.91224 (15)0.34048 (11)0.0348 (3)
H7A0.39970.83590.38620.042*
C1A0.38045 (18)0.59817 (14)0.07361 (10)0.0284 (3)
H1AA0.43260.66730.02560.034*
C2A0.23439 (17)0.45892 (13)0.02440 (10)0.0269 (3)
C3A0.15517 (19)0.43569 (15)−0.08628 (11)0.0325 (3)
C4A0.0176 (2)0.30824 (17)−0.13529 (12)0.0411 (4)
H4AA−0.03300.2975−0.21110.049*
C5A−0.0459 (2)0.19599 (17)−0.07250 (14)0.0479 (4)
H5AA−0.14140.1067−0.10500.057*
C6A0.0291 (2)0.21259 (16)0.03835 (13)0.0468 (4)
H6AA−0.01480.13460.08130.056*
C7A0.1674 (2)0.34260 (15)0.08573 (11)0.0361 (3)
H7AA0.21800.35320.16150.043*
C1B0.67867 (17)0.65547 (14)0.35664 (10)0.0281 (3)
H1BA0.58310.56520.32630.034*
C2B0.80098 (17)0.65923 (13)0.45521 (10)0.0276 (3)
C3B0.76856 (18)0.54090 (14)0.51567 (11)0.0305 (3)
C4B0.8769 (2)0.54521 (16)0.61103 (12)0.0367 (3)
H4BA0.84950.46300.65150.044*
C5B1.0254 (2)0.67148 (17)0.64619 (12)0.0409 (4)
H5BA1.10140.67640.71150.049*
C6B1.0645 (2)0.79119 (16)0.58684 (12)0.0408 (4)
H6BA1.16750.87750.61100.049*
C7B0.95321 (19)0.78464 (14)0.49220 (11)0.0335 (3)
H7BA0.98090.86690.45180.040*

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
F10.0633 (7)0.0747 (7)0.0551 (6)0.0276 (6)0.0245 (5)0.0366 (5)
F1A0.0650 (7)0.0515 (5)0.0334 (4)0.0138 (5)−0.0069 (4)0.0125 (4)
F1B0.0381 (5)0.0310 (4)0.0537 (5)0.0007 (4)0.0004 (4)0.0093 (4)
N1A0.0280 (6)0.0319 (5)0.0289 (5)0.0041 (5)−0.0036 (5)0.0032 (4)
N1B0.0261 (6)0.0322 (5)0.0328 (5)0.0068 (5)−0.0042 (5)0.0047 (4)
C10.0253 (7)0.0308 (6)0.0286 (6)0.0035 (5)−0.0018 (5)0.0056 (5)
C20.0223 (6)0.0282 (6)0.0279 (6)0.0011 (5)−0.0053 (5)0.0043 (5)
C30.0288 (7)0.0393 (7)0.0314 (6)0.0039 (6)0.0012 (6)0.0117 (6)
C40.0439 (9)0.0345 (7)0.0473 (8)0.0078 (7)−0.0039 (7)0.0168 (6)
C50.0429 (9)0.0327 (7)0.0489 (8)0.0125 (6)−0.0068 (7)0.0008 (6)
C60.0397 (9)0.0411 (7)0.0363 (7)0.0101 (7)0.0041 (6)0.0016 (6)
C70.0379 (8)0.0317 (6)0.0317 (6)0.0062 (6)0.0030 (6)0.0081 (5)
C1A0.0271 (7)0.0291 (6)0.0282 (6)0.0082 (5)0.0020 (5)0.0056 (5)
C2A0.0252 (7)0.0280 (6)0.0266 (6)0.0106 (5)0.0001 (5)−0.0001 (5)
C3A0.0327 (8)0.0361 (7)0.0294 (6)0.0146 (6)−0.0004 (6)0.0023 (5)
C4A0.0330 (8)0.0471 (8)0.0371 (7)0.0152 (7)−0.0087 (6)−0.0097 (6)
C5A0.0316 (8)0.0408 (8)0.0581 (10)0.0038 (7)−0.0024 (7)−0.0103 (7)
C6A0.0441 (10)0.0343 (7)0.0544 (9)0.0031 (7)0.0059 (8)0.0062 (7)
C7A0.0372 (8)0.0360 (7)0.0326 (7)0.0095 (6)0.0015 (6)0.0051 (5)
C1B0.0236 (7)0.0283 (6)0.0282 (6)0.0052 (5)0.0004 (5)0.0002 (5)
C2B0.0249 (7)0.0278 (6)0.0277 (6)0.0080 (5)−0.0003 (5)0.0008 (5)
C3B0.0278 (7)0.0264 (6)0.0345 (6)0.0066 (5)0.0037 (6)0.0022 (5)
C4B0.0420 (9)0.0373 (7)0.0360 (7)0.0171 (7)0.0054 (6)0.0126 (6)
C5B0.0406 (9)0.0509 (8)0.0327 (7)0.0182 (7)−0.0042 (6)0.0077 (6)
C6B0.0325 (8)0.0401 (7)0.0413 (7)0.0041 (6)−0.0087 (6)0.0033 (6)
C7B0.0306 (7)0.0295 (6)0.0368 (7)0.0055 (6)−0.0025 (6)0.0064 (5)

Geometric parameters (Å, °)

F1—C31.3562 (16)C2A—C7A1.3968 (18)
F1A—C3A1.3571 (16)C3A—C4A1.3681 (19)
F1B—C3B1.3558 (15)C4A—C5A1.376 (2)
N1A—C1A1.2637 (15)C4A—H4AA0.9500
N1A—C11.4725 (16)C5A—C6A1.391 (2)
N1B—C1B1.2632 (15)C5A—H5AA0.9500
N1B—C11.4602 (16)C6A—C7A1.380 (2)
C1—C21.5173 (18)C6A—H6AA0.9500
C1—H1A1.0000C7A—H7AA0.9500
C2—C31.3782 (18)C1B—C2B1.4811 (17)
C2—C71.3958 (19)C1B—H1BA0.9500
C3—C41.377 (2)C2B—C3B1.3856 (17)
C4—C51.383 (2)C2B—C7B1.3957 (17)
C4—H4A0.9500C3B—C4B1.3833 (18)
C5—C61.385 (2)C4B—C5B1.380 (2)
C5—H5A0.9500C4B—H4BA0.9500
C6—C71.383 (2)C5B—C6B1.387 (2)
C6—H6A0.9500C5B—H5BA0.9500
C7—H7A0.9500C6B—C7B1.3846 (18)
C1A—C2A1.4656 (17)C6B—H6BA0.9500
C1A—H1AA0.9500C7B—H7BA0.9500
C2A—C3A1.3914 (16)
C1A—N1A—C1116.40 (11)C4A—C3A—C2A123.58 (13)
C1B—N1B—C1120.47 (10)C3A—C4A—C5A118.57 (13)
N1B—C1—N1A114.48 (10)C3A—C4A—H4AA120.7
N1B—C1—C2108.04 (10)C5A—C4A—H4AA120.7
N1A—C1—C2109.45 (11)C4A—C5A—C6A120.35 (13)
N1B—C1—H1A108.2C4A—C5A—H5AA119.8
N1A—C1—H1A108.2C6A—C5A—H5AA119.8
C2—C1—H1A108.2C7A—C6A—C5A119.82 (14)
C3—C2—C7116.89 (12)C7A—C6A—H6AA120.1
C3—C2—C1121.87 (12)C5A—C6A—H6AA120.1
C7—C2—C1121.24 (11)C6A—C7A—C2A121.23 (12)
F1—C3—C4118.24 (12)C6A—C7A—H7AA119.4
F1—C3—C2118.47 (13)C2A—C7A—H7AA119.4
C4—C3—C2123.29 (13)N1B—C1B—C2B119.11 (11)
C3—C4—C5118.71 (13)N1B—C1B—H1BA120.4
C3—C4—H4A120.6C2B—C1B—H1BA120.4
C5—C4—H4A120.6C3B—C2B—C7B117.18 (11)
C4—C5—C6119.87 (14)C3B—C2B—C1B121.92 (11)
C4—C5—H5A120.1C7B—C2B—C1B120.89 (11)
C6—C5—H5A120.1F1B—C3B—C4B118.11 (12)
C7—C6—C5120.09 (14)F1B—C3B—C2B119.07 (11)
C7—C6—H6A120.0C4B—C3B—C2B122.82 (12)
C5—C6—H6A120.0C5B—C4B—C3B118.61 (13)
C6—C7—C2121.14 (13)C5B—C4B—H4BA120.7
C6—C7—H7A119.4C3B—C4B—H4BA120.7
C2—C7—H7A119.4C4B—C5B—C6B120.43 (12)
N1A—C1A—C2A122.22 (12)C4B—C5B—H5BA119.8
N1A—C1A—H1AA118.9C6B—C5B—H5BA119.8
C2A—C1A—H1AA118.9C7B—C6B—C5B119.84 (13)
C3A—C2A—C7A116.45 (12)C7B—C6B—H6BA120.1
C3A—C2A—C1A121.58 (11)C5B—C6B—H6BA120.1
C7A—C2A—C1A121.97 (11)C6B—C7B—C2B121.11 (12)
F1A—C3A—C4A118.62 (11)C6B—C7B—H7BA119.4
F1A—C3A—C2A117.81 (12)C2B—C7B—H7BA119.4
C1B—N1B—C1—N1A2.17 (18)C7A—C2A—C3A—C4A0.7 (2)
C1B—N1B—C1—C2124.39 (13)C1A—C2A—C3A—C4A−179.39 (13)
C1A—N1A—C1—N1B−152.10 (12)F1A—C3A—C4A—C5A179.56 (13)
C1A—N1A—C1—C286.45 (14)C2A—C3A—C4A—C5A−0.4 (2)
N1B—C1—C2—C3122.02 (13)C3A—C4A—C5A—C6A−0.1 (2)
N1A—C1—C2—C3−112.72 (13)C4A—C5A—C6A—C7A0.2 (2)
N1B—C1—C2—C7−57.86 (15)C5A—C6A—C7A—C2A0.0 (2)
N1A—C1—C2—C767.40 (14)C3A—C2A—C7A—C6A−0.5 (2)
C7—C2—C3—F1178.64 (11)C1A—C2A—C7A—C6A179.60 (14)
C1—C2—C3—F1−1.25 (18)C1—N1B—C1B—C2B179.50 (12)
C7—C2—C3—C4−0.6 (2)N1B—C1B—C2B—C3B171.37 (12)
C1—C2—C3—C4179.50 (13)N1B—C1B—C2B—C7B−7.51 (19)
F1—C3—C4—C5−179.35 (13)C7B—C2B—C3B—F1B−178.25 (12)
C2—C3—C4—C5−0.1 (2)C1B—C2B—C3B—F1B2.83 (19)
C3—C4—C5—C60.9 (2)C7B—C2B—C3B—C4B1.9 (2)
C4—C5—C6—C7−0.9 (2)C1B—C2B—C3B—C4B−177.00 (13)
C5—C6—C7—C20.2 (2)F1B—C3B—C4B—C5B178.88 (12)
C3—C2—C7—C60.54 (19)C2B—C3B—C4B—C5B−1.3 (2)
C1—C2—C7—C6−179.57 (12)C3B—C4B—C5B—C6B0.0 (2)
C1—N1A—C1A—C2A−179.66 (11)C4B—C5B—C6B—C7B0.5 (2)
N1A—C1A—C2A—C3A171.24 (13)C5B—C6B—C7B—C2B0.2 (2)
N1A—C1A—C2A—C7A−8.8 (2)C3B—C2B—C7B—C6B−1.3 (2)
C7A—C2A—C3A—F1A−179.31 (12)C1B—C2B—C7B—C6B177.59 (13)
C1A—C2A—C3A—F1A0.63 (19)

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
C5B—H5BA···F1Ai0.952.533.3871 (16)151

Symmetry codes: (i) x+1, y, z+1.

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: CV2683).

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