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Acta Crystallogr Sect E Struct Rep Online. 2008 June 1; 64(Pt 6): o1121.
Published online 2008 May 21. doi:  10.1107/S1600536808014670
PMCID: PMC2961585

(1Z,1′Z,3E,3′E)-1,1′-Diphenyl-3,3′-[(1S,2S)-cyclo­hexane-1,2-diyldinitrilo]dibut-1-en-1-ol

Abstract

A new tetra­dentate chiral Schiff base ligand, C26H30N2O2, has been synthesized by the reaction of 1-phenyl­butane-1,3-dione with (1S,2S)-(−)-1,2-diamino­cyclo­hexane. The chiral centers in the mol­ecule have the same S configuration, since the absolute configuration was determined by that of the starting reagent (1S,2S)-(−)-1,2-diamino­hexane. The cyclo­hexane ring is in a chair conformation, and the substituents are equatorial in the most stable conformation (trans-cyclo­hexyl). The crystal structure is stabilized by two intra­molecular O—H(...)N hydrogen bonds and a weak C—H(...)π inter­action.

Related literature

For the chemistry of Schiff bases, see: Alemi & Shaabani (2000 [triangle]); Bandini et al. (1999 [triangle], 2000 [triangle]); Belokon et al. (1997 [triangle]); Cozzi (2003 [triangle]); Jiang et al. (1995 [triangle]); Kureshy et al. (2001 [triangle]); Sasaki et al. (1991 [triangle]).

An external file that holds a picture, illustration, etc.
Object name is e-64-o1121-scheme1.jpg

Experimental

Crystal data

  • C26H30N2O2
  • M r = 402.52
  • Orthorhombic, An external file that holds a picture, illustration, etc.
Object name is e-64-o1121-efi1.jpg
  • a = 8.9073 (11) Å
  • b = 10.1205 (13) Å
  • c = 26.476 (3) Å
  • V = 2386.7 (5) Å3
  • Z = 4
  • Mo Kα radiation
  • μ = 0.07 mm−1
  • T = 293 (2) K
  • 0.20 × 0.20 × 0.20 mm

Data collection

  • Rigaku SCXmini diffractometer
  • Absorption correction: multi-scan (CrystalClear; Rigaku, 2005 [triangle]) T min = 0.980, T max = 0.990
  • 22130 measured reflections
  • 2683 independent reflections
  • 1952 reflections with I > 2σ(I)
  • R int = 0.062

Refinement

  • R[F 2 > 2σ(F 2)] = 0.061
  • wR(F 2) = 0.159
  • S = 1.07
  • 2683 reflections
  • 275 parameters
  • H-atom parameters constrained
  • Δρmax = 0.29 e Å−3
  • Δρmin = −0.17 e Å−3

Data collection: CrystalClear (Rigaku, 2005 [triangle]); cell refinement: CrystalClear; data reduction: CrystalClear; 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: SHELXL97.

Table 1
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536808014670/bx2143sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808014670/bx2143Isup2.hkl

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

Acknowledgments

This work was supported by a Start-up Grant from Southeast University to ZRQ.

supplementary crystallographic information

Comment

In recent years, research on Schiff bases has been intensified for the reason that some of them can form materials with non-linear optical (NLO) activity (Alemi & Shaabani, 2000), and some can be used for the asymmetric oxidation of methyl phenyl sulfides (Sasaki et al., 1991). The search for new chiral ligands for asymmetric synthesis is an important task in organic chemistry. Various chiral Schiff bases are widely used in asymmetric reactions (Jiang et al., 1995; Belokon et al., 1997; Bandini et al., 1999, 2000; Kureshy et al., 2001; Cozzi, 2003). Herein, we report the synthesis and crystal structure of a new chiral Schiff base ligand (1Z,1'Z,3E,3'E)-3,3'-((1S,2S)-cyclohexane-1,2-diylbis(azan-1-yl-1-ylidene))bis(1-phenylbut-1-en-1-ol). Fig. 1 show, the absolute configurations of the chiral centers and they have the same chirality (S-configuration). The cyclohexane ring is of chair conformation, and the substituents are equatorial in the most stable conformation of trans-cyclohexyl. The crystal structure is stabilized by two intramolecular O—H···N hydrogen bonds and a weak C—H···π interaction (Table 1).

Experimental

1-phenylbutane-1,3-dione (3.89 g, 0.024 mol) in 6 ml of chloroform was added dropwise to a solution of chloroform (20 ml) containing (1S, 2S)-(–)-1,2-diaminocyclohexane (1.14 g, 0.01 mol), which was kept at 0–5°C with vigorous stirring during the reaction. After complete addition which took approximately 30 min, the mixture was stirred for another 1 h at room temperature. After the evaporation of the solvent under reduced pressure, the crude product was recrystallized by slowly evaporating with petroleum ether to yield colorless crystals.

Refinement

Positional parameters of all the H atoms were calculated geometrically and were allowed to ride on the C, O atoms to which they are bonded, with C—H = 0.93 to 0.98Å, O—H = 0.82 Å , with Uiso (H) = 1.2Ueq (Caromatic, Cmethylene), Uiso(H) = 1.5Ueq (Cmethyl) or 1.5 Ueq(O). In the absence of significant anomalous scattering effects, 2006 Friedel pairs were merged.

Figures

Fig. 1.
A view of the compound with the atomic numbering scheme. Displacement ellipsoids were drawn at the 30% probability level.

Crystal data

C26H30N2O2F000 = 864
Mr = 402.52Dx = 1.120 Mg m3
Orthorhombic, P212121Mo Kα radiation λ = 0.71073 Å
Hall symbol: P 2ac 2abCell parameters from 4136 reflections
a = 8.9073 (11) Åθ = 3.1–27.5º
b = 10.1205 (13) ŵ = 0.07 mm1
c = 26.476 (3) ÅT = 293 (2) K
V = 2386.7 (5) Å3Block, colorless
Z = 40.20 × 0.20 × 0.20 mm

Data collection

Rigaku SCXmini diffractometer2683 independent reflections
Radiation source: fine-focus sealed tube1952 reflections with I > 2σ(I)
Monochromator: graphiteRint = 0.062
Detector resolution: 13.6612 pixels mm-1θmax = 26.0º
T = 293(2) Kθmin = 2.4º
ω scansh = −10→10
Absorption correction: multi-scan(CrystalClear; Rigaku, 2005)k = −12→12
Tmin = 0.980, Tmax = 0.990l = −32→32
22130 measured reflections

Refinement

Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.061H-atom parameters constrained
wR(F2) = 0.159  w = 1/[σ2(Fo2) + (0.0753P)2 + 0.2595P] where P = (Fo2 + 2Fc2)/3
S = 1.07(Δ/σ)max < 0.001
2683 reflectionsΔρmax = 0.29 e Å3
275 parametersΔρmin = −0.17 e Å3
Primary atom site location: structure-invariant direct methodsExtinction correction: none

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
N20.8242 (3)0.2435 (3)0.96116 (10)0.0576 (7)
C170.8209 (4)0.1345 (3)0.92486 (12)0.0562 (8)
H170.90720.14340.90210.067*
N10.6697 (4)0.2620 (3)0.86429 (10)0.0618 (8)
O20.7103 (3)0.3353 (2)1.04671 (9)0.0684 (7)
H2A0.71890.28381.02300.103*
C1'0.7786 (4)0.4406 (3)1.03675 (13)0.0582 (8)
C180.8342 (5)0.0039 (3)0.95283 (14)0.0669 (10)
H18A0.92900.00140.97080.080*
H18B0.7541−0.00250.97760.080*
C20.6168 (4)0.4861 (4)0.84749 (13)0.0597 (9)
H20.56300.56130.85640.072*
C3'0.8907 (4)0.3615 (4)0.95676 (13)0.0571 (8)
C30.5973 (4)0.3737 (4)0.87611 (13)0.0597 (9)
C210.6703 (6)0.0219 (4)0.85724 (15)0.0776 (12)
H21A0.57610.02380.83890.093*
H21B0.75120.02910.83290.093*
O10.7936 (4)0.3983 (3)0.79076 (10)0.0852 (9)
H10.78750.33760.81120.128*
C160.6767 (4)0.1386 (3)0.89317 (13)0.0584 (9)
H160.58990.13450.91590.070*
C40.7242 (4)0.6191 (4)0.77629 (13)0.0653 (10)
C2'0.8698 (4)0.4569 (4)0.99355 (13)0.0618 (9)
H2'0.91920.53720.98960.074*
C100.7610 (4)0.5522 (4)1.07347 (14)0.0648 (9)
C230.9890 (5)0.3907 (4)0.91182 (14)0.0684 (10)
H23A0.93300.37650.88130.103*
H23B1.07470.33320.91230.103*
H23C1.02190.48090.91320.103*
C10.7137 (4)0.4938 (4)0.80549 (13)0.0629 (9)
C220.4918 (5)0.3766 (4)0.92075 (15)0.0778 (12)
H22A0.54380.34690.95040.117*
H22B0.40790.31940.91430.117*
H22C0.45650.46520.92590.117*
C190.8253 (5)−0.1133 (4)0.91717 (15)0.0772 (11)
H19A0.9126−0.11360.89530.093*
H19B0.8262−0.19460.93660.093*
C200.6840 (6)−0.1081 (4)0.88527 (18)0.0847 (12)
H20A0.6855−0.18010.86110.102*
H20B0.5971−0.11970.90690.102*
C150.7371 (5)0.5242 (4)1.12405 (15)0.0771 (11)
H150.73280.43681.13480.093*
C90.6005 (5)0.6985 (4)0.76822 (16)0.0787 (12)
H90.50800.67440.78170.094*
C110.7644 (5)0.6836 (4)1.05852 (18)0.0824 (13)
H110.77930.70471.02470.099*
C120.7458 (6)0.7824 (5)1.0933 (2)0.1040 (17)
H120.74830.87011.08280.125*
C80.6128 (7)0.8127 (5)0.74050 (19)0.1055 (17)
H80.52900.86580.73520.127*
C140.7197 (7)0.6255 (5)1.15854 (18)0.1006 (16)
H140.70490.60651.19250.121*
C50.8588 (5)0.6560 (6)0.75543 (18)0.1002 (16)
H50.94250.60220.75970.120*
C130.7242 (6)0.7548 (6)1.1424 (2)0.1062 (18)
H130.71230.82321.16550.127*
C60.8718 (8)0.7720 (7)0.7282 (3)0.133 (2)
H60.96400.79790.71500.160*
C70.7471 (11)0.8477 (6)0.7210 (2)0.126 (2)
H70.75460.92510.70230.152*

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
N20.0638 (17)0.0557 (16)0.0532 (15)−0.0045 (15)0.0003 (14)−0.0004 (14)
C170.061 (2)0.0553 (19)0.0528 (17)0.0016 (18)0.0041 (16)0.0009 (16)
N10.0690 (19)0.0633 (18)0.0531 (15)0.0081 (17)−0.0017 (15)0.0041 (14)
O20.0813 (18)0.0624 (15)0.0614 (14)−0.0075 (15)0.0111 (14)−0.0046 (12)
C1'0.062 (2)0.0504 (18)0.0618 (19)−0.0020 (18)−0.0071 (18)0.0042 (17)
C180.077 (3)0.059 (2)0.065 (2)0.003 (2)−0.006 (2)0.0059 (18)
C20.063 (2)0.061 (2)0.0551 (18)0.0043 (18)0.0048 (17)0.0030 (17)
C3'0.0552 (19)0.0579 (19)0.0582 (19)−0.0051 (17)−0.0012 (17)0.0089 (17)
C30.059 (2)0.070 (2)0.0505 (18)0.006 (2)0.0025 (16)0.0044 (18)
C210.091 (3)0.073 (3)0.069 (2)−0.002 (2)−0.013 (2)−0.011 (2)
O10.091 (2)0.097 (2)0.0675 (16)0.0300 (19)0.0233 (16)0.0236 (15)
C160.065 (2)0.0539 (19)0.0566 (18)0.0023 (19)0.0052 (18)0.0011 (16)
C40.065 (2)0.077 (2)0.0537 (18)−0.010 (2)−0.0035 (18)0.0070 (19)
C2'0.067 (2)0.0527 (19)0.066 (2)−0.0099 (18)0.0021 (18)0.0005 (18)
C100.061 (2)0.061 (2)0.072 (2)0.0020 (19)−0.0050 (19)−0.0072 (19)
C230.067 (2)0.072 (2)0.066 (2)−0.007 (2)0.0063 (19)0.008 (2)
C10.058 (2)0.074 (2)0.0565 (18)0.009 (2)0.0001 (17)0.0050 (19)
C220.080 (3)0.083 (3)0.070 (2)0.014 (2)0.026 (2)0.014 (2)
C190.090 (3)0.056 (2)0.086 (3)0.006 (2)0.004 (2)0.001 (2)
C200.100 (3)0.060 (2)0.094 (3)−0.001 (2)−0.003 (3)−0.015 (2)
C150.082 (3)0.083 (3)0.067 (2)0.004 (2)−0.005 (2)−0.008 (2)
C90.078 (3)0.083 (3)0.076 (3)0.001 (2)−0.012 (2)0.020 (2)
C110.088 (3)0.064 (2)0.095 (3)0.000 (2)0.007 (3)−0.001 (2)
C120.106 (4)0.064 (3)0.142 (5)0.002 (3)0.016 (4)−0.023 (3)
C80.136 (5)0.090 (3)0.090 (3)−0.001 (4)−0.018 (3)0.031 (3)
C140.110 (4)0.114 (4)0.078 (3)0.014 (4)−0.010 (3)−0.030 (3)
C50.077 (3)0.124 (4)0.100 (3)−0.017 (3)0.012 (3)0.031 (3)
C130.096 (4)0.091 (4)0.131 (5)0.001 (3)0.001 (4)−0.054 (4)
C60.120 (5)0.149 (6)0.130 (5)−0.056 (5)0.021 (4)0.039 (5)
C70.180 (7)0.099 (4)0.100 (4)−0.037 (5)−0.006 (5)0.034 (3)

Geometric parameters (Å, °)

N2—C3'1.338 (4)C10—C151.385 (5)
N2—C171.463 (4)C10—C111.388 (5)
C17—C181.520 (5)C23—H23A0.9600
C17—C161.535 (5)C23—H23B0.9600
C17—H170.9800C23—H23C0.9600
N1—C31.339 (5)C22—H22A0.9600
N1—C161.465 (4)C22—H22B0.9600
O2—C1'1.255 (4)C22—H22C0.9600
O2—H2A0.8200C19—C201.517 (6)
C1'—C2'1.413 (5)C19—H19A0.9700
C1'—C101.498 (5)C19—H19B0.9700
C18—C191.518 (5)C20—H20A0.9700
C18—H18A0.9700C20—H20B0.9700
C18—H18B0.9700C15—C141.382 (6)
C2—C31.378 (5)C15—H150.9300
C2—C11.409 (5)C9—C81.374 (6)
C2—H20.9300C9—H90.9300
C3'—C2'1.384 (5)C11—C121.370 (6)
C3'—C231.506 (5)C11—H110.9300
C3—C221.510 (5)C12—C131.341 (7)
C21—C201.515 (5)C12—H120.9300
C21—C161.517 (5)C8—C71.350 (8)
C21—H21A0.9700C8—H80.9300
C21—H21B0.9700C14—C131.377 (7)
O1—C11.262 (4)C14—H140.9300
O1—H10.8200C5—C61.382 (8)
C16—H160.9800C5—H50.9300
C4—C51.372 (6)C13—H130.9300
C4—C91.380 (5)C6—C71.363 (9)
C4—C11.488 (5)C6—H60.9300
C2'—H2'0.9300C7—H70.9300
C3'—N2—C17128.6 (3)H23A—C23—H23C109.5
N2—C17—C18109.5 (3)H23B—C23—H23C109.5
N2—C17—C16110.8 (3)O1—C1—C2123.2 (3)
C18—C17—C16110.8 (3)O1—C1—C4117.2 (3)
N2—C17—H17108.6C2—C1—C4119.7 (3)
C18—C17—H17108.6C3—C22—H22A109.5
C16—C17—H17108.6C3—C22—H22B109.5
C3—N1—C16128.2 (3)H22A—C22—H22B109.5
C1'—O2—H2A109.5C3—C22—H22C109.5
O2—C1'—C2'123.2 (3)H22A—C22—H22C109.5
O2—C1'—C10116.9 (3)H22B—C22—H22C109.5
C2'—C1'—C10119.8 (3)C20—C19—C18111.2 (3)
C19—C18—C17111.9 (3)C20—C19—H19A109.4
C19—C18—H18A109.2C18—C19—H19A109.4
C17—C18—H18A109.2C20—C19—H19B109.4
C19—C18—H18B109.2C18—C19—H19B109.4
C17—C18—H18B109.2H19A—C19—H19B108.0
H18A—C18—H18B107.9C21—C20—C19111.7 (4)
C3—C2—C1123.8 (3)C21—C20—H20A109.3
C3—C2—H2118.1C19—C20—H20A109.3
C1—C2—H2118.1C21—C20—H20B109.3
N2—C3'—C2'120.1 (3)C19—C20—H20B109.3
N2—C3'—C23120.1 (3)H20A—C20—H20B107.9
C2'—C3'—C23119.8 (3)C14—C15—C10120.3 (4)
N1—C3—C2120.5 (3)C14—C15—H15119.9
N1—C3—C22119.9 (3)C10—C15—H15119.9
C2—C3—C22119.6 (3)C8—C9—C4120.6 (5)
C20—C21—C16111.5 (3)C8—C9—H9119.7
C20—C21—H21A109.3C4—C9—H9119.7
C16—C21—H21A109.3C12—C11—C10120.3 (5)
C20—C21—H21B109.3C12—C11—H11119.8
C16—C21—H21B109.3C10—C11—H11119.8
H21A—C21—H21B108.0C13—C12—C11121.1 (5)
C1—O1—H1109.5C13—C12—H12119.4
N1—C16—C21109.5 (3)C11—C12—H12119.4
N1—C16—C17110.1 (3)C7—C8—C9119.7 (6)
C21—C16—C17110.7 (3)C7—C8—H8120.2
N1—C16—H16108.8C9—C8—H8120.2
C21—C16—H16108.8C13—C14—C15119.8 (5)
C17—C16—H16108.8C13—C14—H14120.1
C5—C4—C9118.5 (4)C15—C14—H14120.1
C5—C4—C1119.7 (4)C4—C5—C6120.9 (6)
C9—C4—C1121.8 (4)C4—C5—H5119.5
C3'—C2'—C1'124.5 (3)C6—C5—H5119.5
C3'—C2'—H2'117.8C12—C13—C14120.2 (5)
C1'—C2'—H2'117.8C12—C13—H13119.9
C15—C10—C11118.3 (4)C14—C13—H13119.9
C15—C10—C1'119.3 (3)C7—C6—C5118.8 (6)
C11—C10—C1'122.3 (4)C7—C6—H6120.6
C3'—C23—H23A109.5C5—C6—H6120.6
C3'—C23—H23B109.5C8—C7—C6121.5 (5)
H23A—C23—H23B109.5C8—C7—H7119.3
C3'—C23—H23C109.5C6—C7—H7119.3
C3'—N2—C17—C18141.4 (4)C3—C2—C1—O1−1.2 (6)
C3'—N2—C17—C16−96.1 (4)C3—C2—C1—C4178.6 (3)
N2—C17—C18—C19177.8 (3)C5—C4—C1—O1−34.7 (6)
C16—C17—C18—C1955.2 (4)C9—C4—C1—O1143.5 (4)
C17—N2—C3'—C2'174.1 (3)C5—C4—C1—C2145.5 (4)
C17—N2—C3'—C23−6.1 (5)C9—C4—C1—C2−36.3 (5)
C16—N1—C3—C2172.3 (3)C17—C18—C19—C20−54.6 (5)
C16—N1—C3—C22−8.4 (6)C16—C21—C20—C19−55.7 (5)
C1—C2—C3—N1−1.4 (6)C18—C19—C20—C2154.4 (5)
C1—C2—C3—C22179.4 (4)C11—C10—C15—C14−1.0 (7)
C3—N1—C16—C21141.4 (4)C1'—C10—C15—C14−179.6 (4)
C3—N1—C16—C17−96.7 (4)C5—C4—C9—C8−0.9 (6)
C20—C21—C16—N1177.5 (4)C1—C4—C9—C8−179.1 (4)
C20—C21—C16—C1756.0 (5)C15—C10—C11—C120.6 (7)
N2—C17—C16—N161.4 (3)C1'—C10—C11—C12179.1 (4)
C18—C17—C16—N1−176.9 (3)C10—C11—C12—C130.0 (9)
N2—C17—C16—C21−177.4 (3)C4—C9—C8—C70.0 (7)
C18—C17—C16—C21−55.6 (4)C10—C15—C14—C130.8 (8)
N2—C3'—C2'—C1'−1.1 (6)C9—C4—C5—C61.9 (7)
C23—C3'—C2'—C1'179.1 (3)C1—C4—C5—C6−179.9 (5)
O2—C1'—C2'—C3'2.2 (6)C11—C12—C13—C14−0.3 (9)
C10—C1'—C2'—C3'−178.4 (3)C15—C14—C13—C12−0.2 (9)
O2—C1'—C10—C1530.0 (5)C4—C5—C6—C7−2.0 (9)
C2'—C1'—C10—C15−149.4 (4)C9—C8—C7—C60.0 (10)
O2—C1'—C10—C11−148.5 (4)C5—C6—C7—C81.0 (11)
C2'—C1'—C10—C1132.1 (6)

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
O2—H2A···N20.821.932.650 (3)146
O1—H1···N10.821.912.629 (4)145
C19—H19A···Cg3i0.972.963.795 (5)144

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

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: BX2143).

References

  • Alemi, A. A. & Shaabani, B. (2000). Acta Chim. Slov.47, 363–369.
  • Bandini, M., Cozzi, P. G., Melchioree, P. & Umani-Ronchi, A. (1999). Angew. Chem. Int. Ed.38, 3357–3359. [PubMed]
  • Bandini, M., Cozzi, P. G. & Umani-Ronchi, A. (2000). Angew. Chem. Int. Ed.39, 2327–2330. [PubMed]
  • Belokon, Y., Flego, M., Ikonnikov, N., Moscalenko, M., North, M., Orizu, C., Tararov, V. & Tasinazzo, M. (1997). J. Chem. Soc. Perkin Trans. 1, pp. 1293–1295.
  • Cozzi, P. G. (2003). Angew. Chem. Int. Ed.42, 2895–2898. [PubMed]
  • Jiang, Y., Zhou, X., Hu, W., Wu, L. & Mi, A. (1995). Tetrahedron Asymmetry, 6, 405–408.
  • Kureshy, R. I., Khan, N. H., Abdi, S. H. R., Patel, S. T. & Jasra, R. V. (2001). Tetrahedron Lett.42, 2915–2918.
  • Rigaku (2005). CrystalClear Rigaku Corporation, Tokyo, Japan.
  • Sasaki, C., Nakajima, K. & Kojima, M. (1991). Bull. Chem. Soc. Jpn, 64, 1318–1324.
  • Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. [PubMed]

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