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Acta Cryst. (2008). E64, o1784    [ doi:10.1107/S1600536808026196 ]

(R)-3,4,5-Trideoxy-5,6-didehydro-1,2-O-(2,2,2-trichloroethylidene)-[alpha]-D-glucofuranose-6,3-carbolactone: a new derivative of [alpha]-chloralose

V. Aburto-Luna, R.-L. Meza-León and S. Bernès

Abstract top

The title compound [systematic name: (R)-2-trichloromethyl-3a,3b,7a,8a-tetrahydro-5H-pyrano[2',3':4,5]furano[2,3-d][1,3]dioxol-5-one], C9H7Cl3O5, a triyclic system that contains a central [alpha]-D-furanose ring cis-fused with a dioxolane ring as well as a [delta]-lactone ring, exhibits a twisted conformation. The CCl3 group has an axial orientation. The furanose ring approximates an envelope conformation due to the [alpha],[beta]-unsaturated lactone functionality. The asymmetric unit contains two independent molecules with almost identical geometries.

Comment top

α-Chloralose [1,2-O-(2,2,2-trichloroethylidene)-α-D-glucofuranose, (1) in Scheme 2] is an easily available carbohydrate derivative, bearing well studied biological properties. It is a mild hypnotic drug, which is currently used as an anesthetic in veterinary medicine, as a rodenticide, etc. It has been characterized as a molecule possessing potent CNS activity, and has been evaluated in human and animal models, for its therapeutic properties (Collins et al., 1983). A number of α-chloralose derivatives have been prepared (e.g., Zosimo-Landolfo & Tronchet, 1999), since it is known that trichloroethylidene acetals are potential biologically active compounds.

On the other hand, δ-lactones are important flavor and aroma constituents found in many natural products. In some instances, δ-lactone derivatives have been shown to have anti-cancer and apoptosis inducing properties against various human tumors and animal cell lines (Wu et al., 1992).

We have synthesized a compound combining both functionalities, (I), with the hope that this compound will also cumulate properties corresponding to each functionality. The starting material was α-chloralose, (1, scheme 2), which was first oxidized into an aldehyde, (2), and then transformed to the corresponding acrylic acid (3) via a Wittig reaction affording a pure Z isomer. Cyclization furnished the lactone (I).

The asymmetric unit of (I) contains two molecules (Figs. 1 and 2), with almost identical geometry. A fit between two independent molecules (non-H atoms) gives a r.m.s. deviation of 0.103 Å. The tricyclic system includes a central α-D-furanose ring approximating an envelope conformation, with C7a as flap atom (C17a in the other molecule). This ring is cis-fused with a dioxolane ring, which may be considered as twisted on O3 and C8 (O13 and C18, resp.). The CCl3 substituent has an axial orientation, as in α-chloralose. Finally, the α,β-unsaturated δ-lactone ring is cis-fused with the furanose, and displays a rigid envelope conformation, with a total puckering amplitude of 0.347 (4) Å [0.361 (4) Å for the second molecule]. Molecules are well separated in the crystal, and no significant intermolecular contacts are detected.

Related literature top

For background regarding α-chloralose and δ lactones, see: Collins et al. (1983); Zosimo-Landolfo & Tronchet (1999); Wu et al. (1992).

Experimental top

The synthesis of (I) is depicted in scheme 2. A solution of α-chloralose (5 g, 16.23 mmol) in ethanol (60 ml) was mixed with a solution of NaIO4 (3.47 g, 16.23 mmol) in H2O (6 ml). After stirring this solution at 298 K for 1 h., a white precipitate appeared, which was washed with ethanol. The filtrates were combined and concentrated under reduced pressure to give a solid product, (2). Ethyl-triphenylphosphoranylidene (6.64 g, 19.06 mmol) was added to a solution of (2), and stirred for 2 h. at 298 K. The mixture was then extracted with CH2Cl2, in order to eliminate oxide triphenylphosphine, acidified until pH 3, and extracted again with ethyl acetate. The organic phase was dried over Na2SO4 and concentrated, to give (3) as a very thick syrup. By adding N,N'-dicyclohexylcarbodiimide (DCC) to a dry-CH2Cl2 solution of (3), under Ar, the lactone (I) was formed over 2 h. The solution was filtered in order to eliminate urea, and the filtrate concentrated, to give (I) as a white solid (3.58 g, 11.93 mmol; 73% yield). NMR and mass spectra are in agreement with the X-ray structure (see archived CIF). Single crystals were obtained by evaporation of an AcOEt solution of (I), at 298 K.

Refinement top

The absolute configuration was assigned after refining the Flack parameter (Flack, 1983), using 2010 measured Friedel pairs. All H atoms were placed in idealized positions, and refined as riding to their carrier atoms. C—H bond lengths were fixed to 0.93 (Csp2—H bonds) or 0.98 Å (methine CH groups), and isotropic displacement parameters calculated as Uiso(H) = 1.2Ueq(carrier C).

Computing details top

Data collection: XSCANS (Siemens, 1996); cell refinement: XSCANS (Siemens, 1996); data reduction: XSCANS (Siemens, 1996); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: Mercury (Macrae et al., 2006); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. Structure of the first independent molecule. Displacement ellipsoids are shown at the 30% probability level.
[Figure 2] Fig. 2. Structure of the second independent molecule. Displacement ellipsoids are shown at the 30% probability level.
[Figure 3] Fig. 3. The synthesis of (I)
(R)-2-Trichloromethyl-3a,3b,7a,8a-tetrahydro-5H- pyrano[2',3':4,5]furano[2,3-d][1,3]dioxol-5-one top
Crystal data top
C9H7Cl3O5Dx = 1.682 Mg m−3
Mr = 301.50Melting point = 416–418 K
Orthorhombic, P212121Mo Kα radiation
λ = 0.71073 Å
Hall symbol: P 2ac 2abCell parameters from 78 reflections
a = 9.129 (4) Åθ = 4.6–12.4º
b = 11.264 (4) ŵ = 0.77 mm−1
c = 23.156 (7) ÅT = 298 (1) K
V = 2381.1 (15) Å3Cell measurement pressure: 101(2) kPa
Z = 8Prism, colourless
F000 = 12160.60 × 0.40 × 0.10 mm
Data collection top
Siemens P4
diffractometer		Rint = 0.044
Radiation source: fine-focus sealed tubeθmax = 26.2º
Monochromator: graphiteθmin = 1.8º
T = 298(1) Kh = −11→11
ω scansk = −14→14
Absorption correction: ψ scan
(XSCANS; Siemens, 1996)		l = −28→28
Tmin = 0.803, Tmax = 0.9263 standard reflections
6901 measured reflections every 97 reflections
4735 independent reflections intensity decay: 2%
3838 reflections with I > 2σ(I)
Refinement top
Refinement on F2Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: fullH-atom parameters constrained
R[F2 > 2σ(F2)] = 0.044  w = 1/[σ2(Fo2) + (0.0319P)2 + 1.7306P]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.111(Δ/σ)max < 0.001
S = 1.06Δρmax = 0.34 e Å−3
4735 reflectionsΔρmin = −0.35 e Å−3
307 parametersExtinction correction: none
Primary atom site location: structure-invariant direct methodsAbsolute structure: Flack (1983), 2010 Friedel pairs
Secondary atom site location: difference Fourier mapFlack parameter: 0.04 (8)
Crystal data top
C9H7Cl3O5V = 2381.1 (15) Å3
Mr = 301.50Z = 8
Orthorhombic, P212121Mo Kα
a = 9.129 (4) ŵ = 0.77 mm−1
b = 11.264 (4) ÅT = 298 (1) K
c = 23.156 (7) Å0.60 × 0.40 × 0.10 mm
Data collection top
Siemens P4
diffractometer		3838 reflections with I > 2σ(I)
Absorption correction: ψ scan
(XSCANS; Siemens, 1996)		Rint = 0.044
Tmin = 0.803, Tmax = 0.9263 standard reflections
6901 measured reflections every 97 reflections
4735 independent reflections intensity decay: 2%
Refinement top
R[F2 > 2σ(F2)] = 0.044H-atom parameters constrained
wR(F2) = 0.111Δρmax = 0.34 e Å−3
S = 1.06Δρmin = −0.35 e Å−3
4735 reflectionsAbsolute structure: Flack (1983), 2010 Friedel pairs
307 parametersFlack parameter: 0.04 (8)
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Cl11.0538 (2)0.40323 (18)0.81819 (5)0.1242 (7)
Cl20.80275 (18)0.39332 (15)0.74470 (6)0.1046 (5)
Cl30.87777 (16)0.60974 (15)0.80223 (5)0.0921 (4)
O11.0741 (4)0.3469 (3)0.60422 (14)0.0810 (10)
C21.1264 (5)0.4432 (4)0.63415 (15)0.0612 (10)
H2A1.22770.46110.62320.073*
O21.1138 (3)0.4251 (3)0.69476 (11)0.0730 (9)
C31.0260 (4)0.5478 (3)0.62175 (13)0.0510 (8)
H3A1.07960.61650.60670.061*
O30.9574 (3)0.5723 (2)0.67532 (9)0.0533 (6)
C3A0.9171 (4)0.5005 (3)0.57924 (14)0.0486 (8)
H3AA0.81860.53170.58650.058*
O40.9700 (3)0.5335 (2)0.52305 (9)0.0540 (6)
C50.9475 (5)0.4644 (4)0.47699 (16)0.0626 (11)
O50.9798 (5)0.5044 (3)0.43064 (11)0.0863 (11)
C60.8919 (7)0.3451 (4)0.4862 (2)0.0852 (16)
H6A0.86210.30040.45460.102*
C70.8828 (7)0.2992 (4)0.5377 (2)0.0914 (18)
H7A0.84930.22180.54210.110*
C7A0.9250 (6)0.3685 (4)0.58927 (18)0.0684 (12)
H7AA0.86160.34690.62180.082*
C81.0435 (5)0.5219 (4)0.71861 (14)0.0561 (10)
H8A1.11580.57980.73230.067*
C90.9472 (5)0.4813 (4)0.76875 (16)0.0675 (12)
Cl110.48873 (14)0.45925 (9)0.55424 (4)0.0678 (3)
Cl120.32408 (13)0.58949 (15)0.47031 (5)0.0852 (4)
Cl130.63514 (12)0.59974 (13)0.46866 (4)0.0733 (3)
O110.3340 (3)0.6649 (2)0.68090 (10)0.0568 (7)
C120.3800 (5)0.7463 (3)0.63918 (14)0.0527 (9)
H12A0.33380.82390.64520.063*
O120.3488 (3)0.7016 (3)0.58318 (10)0.0583 (7)
C130.5434 (5)0.7557 (3)0.64229 (13)0.0503 (9)
H13A0.57790.83800.64430.060*
O130.5930 (3)0.6951 (2)0.59195 (10)0.0506 (6)
C13A0.5833 (4)0.6837 (3)0.69550 (14)0.0476 (8)
H13B0.67780.64330.69120.057*
O140.5842 (3)0.7680 (2)0.74220 (10)0.0552 (7)
C150.5407 (5)0.7344 (3)0.79577 (14)0.0547 (9)
O150.5549 (4)0.8058 (3)0.83396 (11)0.0814 (10)
C160.4746 (5)0.6189 (3)0.80334 (14)0.0598 (10)
H16A0.46260.58910.84050.072*
C170.4312 (5)0.5554 (3)0.75938 (15)0.0542 (9)
H17A0.38330.48360.76550.065*
C17A0.4586 (4)0.5981 (3)0.69935 (13)0.0460 (8)
H17B0.47500.53070.67340.055*
C180.4790 (4)0.7002 (3)0.55198 (14)0.0498 (8)
H18A0.48720.77240.52860.060*
C190.4815 (4)0.5908 (3)0.51320 (13)0.0500 (8)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Cl10.1478 (14)0.1669 (16)0.0579 (6)0.0583 (13)0.0186 (8)0.0493 (9)
Cl20.1170 (11)0.1059 (11)0.0909 (9)−0.0468 (9)0.0423 (8)−0.0014 (8)
Cl30.0981 (9)0.1150 (11)0.0632 (6)0.0175 (8)0.0090 (6)−0.0219 (7)
O10.119 (3)0.0595 (19)0.0646 (18)0.0256 (19)0.0019 (19)0.0040 (15)
C20.068 (2)0.074 (3)0.0413 (18)0.009 (2)0.0125 (18)0.0106 (19)
O20.082 (2)0.094 (2)0.0429 (13)0.0327 (18)0.0134 (13)0.0182 (15)
C30.059 (2)0.0539 (19)0.0401 (16)−0.0027 (19)0.0064 (16)0.0059 (15)
O30.0669 (16)0.0559 (14)0.0371 (11)0.0089 (13)0.0027 (11)0.0023 (10)
C3A0.060 (2)0.0480 (19)0.0382 (16)−0.0023 (17)0.0064 (16)0.0007 (15)
O40.0784 (17)0.0454 (13)0.0380 (11)−0.0015 (13)0.0041 (13)0.0050 (10)
C50.089 (3)0.055 (2)0.0439 (19)0.008 (2)0.010 (2)−0.0023 (17)
O50.141 (3)0.0767 (19)0.0410 (13)0.003 (2)0.0180 (18)0.0018 (13)
C60.137 (5)0.059 (3)0.060 (3)−0.015 (3)0.002 (3)−0.015 (2)
C70.153 (5)0.054 (3)0.067 (3)−0.021 (3)0.008 (3)−0.004 (2)
C7A0.106 (4)0.051 (2)0.048 (2)−0.016 (2)0.009 (2)0.0023 (18)
C80.056 (2)0.071 (3)0.0408 (17)0.005 (2)0.0053 (17)0.0085 (17)
C90.075 (3)0.082 (3)0.0449 (19)0.009 (2)0.0119 (19)0.0139 (19)
Cl110.0934 (8)0.0501 (5)0.0599 (5)−0.0081 (5)0.0111 (6)−0.0027 (4)
Cl120.0661 (6)0.1375 (12)0.0518 (5)0.0059 (7)−0.0119 (5)−0.0211 (7)
Cl130.0659 (6)0.1098 (9)0.0443 (5)−0.0028 (6)0.0161 (4)0.0017 (6)
O110.0608 (16)0.0652 (17)0.0443 (13)0.0013 (13)−0.0010 (12)0.0127 (12)
C120.077 (3)0.047 (2)0.0342 (16)0.0121 (19)−0.0010 (17)−0.0003 (15)
O120.0589 (16)0.080 (2)0.0364 (12)0.0177 (14)−0.0038 (11)−0.0060 (12)
C130.075 (3)0.0403 (17)0.0355 (15)−0.0042 (18)0.0029 (16)0.0013 (14)
O130.0557 (14)0.0606 (16)0.0356 (11)−0.0098 (12)0.0012 (10)−0.0033 (11)
C13A0.063 (2)0.0419 (18)0.0377 (16)0.0000 (16)−0.0030 (15)−0.0069 (15)
O140.0838 (18)0.0433 (13)0.0386 (11)−0.0123 (13)−0.0030 (12)−0.0040 (10)
C150.080 (3)0.0457 (18)0.0378 (16)−0.0019 (19)−0.0027 (18)−0.0038 (15)
O150.137 (3)0.0614 (17)0.0461 (14)−0.0131 (19)−0.0012 (17)−0.0150 (14)
C160.093 (3)0.050 (2)0.0359 (16)0.001 (2)−0.0011 (19)0.0065 (15)
C170.080 (3)0.0399 (18)0.0430 (17)−0.0034 (18)−0.0025 (18)0.0076 (15)
C17A0.065 (2)0.0376 (16)0.0356 (14)0.0000 (17)−0.0054 (15)−0.0001 (13)
C180.062 (2)0.0500 (19)0.0376 (15)0.0018 (17)0.0035 (17)0.0075 (15)
C190.053 (2)0.064 (2)0.0326 (14)−0.0013 (19)0.0015 (14)−0.0001 (15)
Geometric parameters (Å, °) top
Cl1—C91.741 (4)Cl11—C191.761 (4)
Cl2—C91.741 (5)Cl12—C191.747 (4)
Cl3—C91.760 (5)Cl13—C191.744 (4)
O1—C21.373 (6)O11—C121.397 (4)
O1—C7A1.426 (6)O11—C17A1.429 (4)
C2—O21.423 (4)C12—O121.420 (4)
C2—C31.520 (6)C12—C131.497 (6)
C2—H2A0.9800C12—H12A0.9800
O2—C81.381 (5)O12—C181.390 (4)
C3—O31.417 (4)C13—O131.424 (4)
C3—C3A1.497 (5)C13—C13A1.520 (5)
C3—H3A0.9800C13—H13A0.9800
O3—C81.395 (4)O13—C181.394 (4)
C3A—O41.436 (4)C13A—O141.439 (4)
C3A—C7A1.507 (6)C13A—C17A1.495 (5)
C3A—H3AA0.9800C13A—H13B0.9800
O4—C51.337 (5)O14—C151.356 (4)
C5—O51.201 (5)C15—O151.202 (4)
C5—C61.452 (7)C15—C161.445 (5)
C6—C71.302 (6)C16—C171.306 (5)
C6—H6A0.9300C16—H16A0.9300
C7—C7A1.478 (6)C17—C17A1.492 (5)
C7—H7A0.9300C17—H17A0.9300
C7A—H7AA0.9800C17A—H17B0.9800
C8—C91.527 (5)C18—C191.526 (5)
C8—H8A0.9800C18—H18A0.9800
C2—O1—C7A108.6 (4)C12—O11—C17A108.3 (3)
O1—C2—O2110.9 (4)O11—C12—O12109.8 (3)
O1—C2—C3107.9 (3)O11—C12—C13108.2 (3)
O2—C2—C3104.4 (3)O12—C12—C13105.6 (3)
O1—C2—H2A111.1O11—C12—H12A111.0
O2—C2—H2A111.1O12—C12—H12A111.0
C3—C2—H2A111.1C13—C12—H12A111.0
C8—O2—C2108.6 (3)C18—O12—C12107.9 (3)
O3—C3—C3A110.6 (3)O13—C13—C12104.1 (3)
O3—C3—C2104.6 (3)O13—C13—C13A109.4 (3)
C3A—C3—C2104.4 (3)C12—C13—C13A103.9 (3)
O3—C3—H3A112.3O13—C13—H13A112.9
C3A—C3—H3A112.3C12—C13—H13A112.9
C2—C3—H3A112.3C13A—C13—H13A112.9
C8—O3—C3107.5 (3)C18—O13—C13106.6 (3)
O4—C3A—C3106.3 (3)O14—C13A—C17A112.7 (3)
O4—C3A—C7A112.3 (3)O14—C13A—C13105.0 (3)
C3—C3A—C7A102.6 (3)C17A—C13A—C13102.1 (3)
O4—C3A—H3AA111.7O14—C13A—H13B112.1
C3—C3A—H3AA111.7C17A—C13A—H13B112.1
C7A—C3A—H3AA111.7C13—C13A—H13B112.1
C5—O4—C3A121.4 (3)C15—O14—C13A120.1 (3)
O5—C5—O4117.2 (4)O15—C15—O14117.0 (3)
O5—C5—C6124.4 (4)O15—C15—C16123.9 (3)
O4—C5—C6118.4 (3)O14—C15—C16119.0 (3)
C7—C6—C5121.6 (4)C17—C16—C15121.7 (3)
C7—C6—H6A119.2C17—C16—H16A119.1
C5—C6—H6A119.2C15—C16—H16A119.1
C6—C7—C7A120.9 (4)C16—C17—C17A119.9 (3)
C6—C7—H7A119.5C16—C17—H17A120.0
C7A—C7—H7A119.5C17A—C17—H17A120.0
O1—C7A—C7110.8 (5)O11—C17A—C17108.4 (3)
O1—C7A—C3A104.6 (4)O11—C17A—C13A104.4 (3)
C7—C7A—C3A112.6 (4)C17—C17A—C13A113.0 (3)
O1—C7A—H7AA109.6O11—C17A—H17B110.3
C7—C7A—H7AA109.6C17—C17A—H17B110.3
C3A—C7A—H7AA109.6C13A—C17A—H17B110.3
O2—C8—O3107.2 (3)O12—C18—O13107.1 (2)
O2—C8—C9109.6 (3)O12—C18—C19109.1 (3)
O3—C8—C9110.1 (3)O13—C18—C19110.3 (3)
O2—C8—H8A110.0O12—C18—H18A110.1
O3—C8—H8A110.0O13—C18—H18A110.1
C9—C8—H8A110.0C19—C18—H18A110.1
C8—C9—Cl1109.3 (3)C18—C19—Cl13108.3 (3)
C8—C9—Cl2111.3 (3)C18—C19—Cl12109.2 (3)
Cl1—C9—Cl2110.3 (3)Cl13—C19—Cl12109.01 (16)
C8—C9—Cl3107.2 (3)C18—C19—Cl11111.3 (2)
Cl1—C9—Cl3109.1 (2)Cl13—C19—Cl11109.7 (2)
Cl2—C9—Cl3109.6 (3)Cl12—C19—Cl11109.3 (2)
C7A—O1—C2—O294.8 (4)C17A—O11—C12—O1299.0 (3)
C7A—O1—C2—C3−19.0 (4)C17A—O11—C12—C13−15.8 (4)
O1—C2—O2—C8−128.5 (4)O11—C12—O12—C18−124.3 (3)
C3—C2—O2—C8−12.5 (5)C13—C12—O12—C18−7.8 (4)
O1—C2—C3—O3113.3 (3)O11—C12—C13—O13107.1 (3)
O2—C2—C3—O3−4.7 (4)O12—C12—C13—O13−10.4 (4)
O1—C2—C3—C3A−2.9 (4)O11—C12—C13—C13A−7.4 (4)
O2—C2—C3—C3A−120.9 (3)O12—C12—C13—C13A−124.9 (3)
C3A—C3—O3—C8132.0 (3)C12—C13—O13—C1825.0 (4)
C2—C3—O3—C820.1 (4)C13A—C13—O13—C18135.5 (3)
O3—C3—C3A—O4151.9 (3)O13—C13—C13A—O14157.7 (3)
C2—C3—C3A—O4−96.1 (3)C12—C13—C13A—O14−91.6 (3)
O3—C3—C3A—C7A−90.1 (4)O13—C13—C13A—C17A−84.5 (3)
C2—C3—C3A—C7A21.9 (4)C12—C13—C13A—C17A26.1 (3)
C3—C3A—O4—C5147.0 (4)C17A—C13A—O14—C1535.4 (5)
C7A—C3A—O4—C535.6 (5)C13—C13A—O14—C15145.7 (3)
C3A—O4—C5—O5171.5 (4)C13A—O14—C15—O15174.2 (4)
C3A—O4—C5—C6−10.9 (6)C13A—O14—C15—C16−8.6 (6)
O5—C5—C6—C7167.8 (6)O15—C15—C16—C17164.2 (5)
O4—C5—C6—C7−9.5 (8)O14—C15—C16—C17−12.7 (7)
C5—C6—C7—C7A1.8 (10)C15—C16—C17—C17A4.1 (7)
C2—O1—C7A—C7154.9 (4)C12—O11—C17A—C17153.7 (3)
C2—O1—C7A—C3A33.4 (4)C12—O11—C17A—C13A33.0 (3)
C6—C7—C7A—O1−93.4 (7)C16—C17—C17A—O11−92.0 (5)
C6—C7—C7A—C3A23.4 (8)C16—C17—C17A—C13A23.2 (5)
O4—C3A—C7A—O180.2 (4)O14—C13A—C17A—O1176.1 (3)
C3—C3A—C7A—O1−33.5 (4)C13—C13A—C17A—O11−35.9 (3)
O4—C3A—C7A—C7−40.1 (6)O14—C13A—C17A—C17−41.4 (4)
C3—C3A—C7A—C7−153.8 (4)C13—C13A—C17A—C17−153.5 (3)
C2—O2—C8—O325.7 (4)C12—O12—C18—O1323.9 (4)
C2—O2—C8—C9145.1 (4)C12—O12—C18—C19143.2 (3)
C3—O3—C8—O2−28.8 (4)C13—O13—C18—O12−30.9 (3)
C3—O3—C8—C9−147.9 (3)C13—O13—C18—C19−149.5 (3)
O2—C8—C9—Cl155.3 (4)O12—C18—C19—Cl13173.3 (2)
O3—C8—C9—Cl1173.0 (3)O13—C18—C19—Cl13−69.4 (3)
O2—C8—C9—Cl2−66.7 (4)O12—C18—C19—Cl1254.7 (3)
O3—C8—C9—Cl251.0 (4)O13—C18—C19—Cl12172.1 (2)
O2—C8—C9—Cl3173.4 (3)O12—C18—C19—Cl11−66.0 (3)
O3—C8—C9—Cl3−68.9 (4)O13—C18—C19—Cl1151.3 (4)
Acknowledgements top

This work was supported by SEP-PROMEP (Mexico) through grant PROMEP/103.5/06/0959.

references
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