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The title compound, C14H20O8, was synthesized from the hydrogenation of tetra­methyl 1,4-cyclo­hexa­diene-1,2,4,5-tetra­carboxyl­ate with a catalytic amount of palladium/carbon. All four carbonyl moieties of the methyl ester groups are on the same face of the chair-conformed ring. The substantial ring distortion associated with the 1,3-diaxial methoxycarbonyl substituents is reflected in the large difference between bond angles as well as torsion angles, respectively, that in undistorted cyclo­hexanes would be approximately the same.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270100013123/fr1298sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270100013123/fr1298Isup2.hkl
Contains datablock I

CCDC reference: 156167

Comment top

In our synthetic studies towards beltenes and cyclacenes (Stoddart, 1989), previously unreported all-cis tetramethyl 1,2,4,5-cyclohexanetetracarboxylate, (I), was required. Although the synthesis of the trans,cis,trans isomer from the hydrogenation of tetrasodium pyromellitate at 423 K with hydrogen at 3000 p.s.i. and W-2 Raney nickel was reported, the stereochemistry was not well established (Longone, 1963; Bailey et al., 1962). We synthesized (I) in 91% yield from the hydrogenation of tetramethyl 1,4-cyclohexadiene-1,2,4,5-tetracarboxylate, (II), with 10% palladium over carbon and 80 p.s.i. of hydrogen in methanol at 298 K (Scheme). While the stereochemistry of (I) could not be determined from elemental and spectral analysis alone, its structure was unambiguously characterized by X-ray crystal structure analysis. Compound (II) was synthesized from the Diels-Alder reaction of dimethyl acetylenedicarboxylate and dimethyl 2,3-di(methylene)-1,4-butanedioate (Hamon & Spurr, 1981) in refluxing toluene. \sch

The molecular structure of (I) with the atom-numbering scheme (Fig. 1) shows it to have a chair conformation, with the methyl ester groups at C2 and C4 axially oriented and those at C1 and C5 equatorially oriented. All four carbonyl (CO) moieties point in the same direction, towards C6 of the cyclohexane chair, an arrangement which reduces the steric interaction among the four carbomethoxyl groups. The molecule has approximate, non-crystallographic mirror symmetry. It can be seen from Table 1 that all the bond lengths within the ring are similar, with a mean distance of 1.534 (4) Å, which compares favorably with the mean C—C ring bond length [1.529 (4) Å] of trans-1,4-dicyanocyclohexane (Echeverria et al., 1995). The largest endocyclic angle, C2—C3—C4, bearing the cis-diaxial C2- and C4-carbomethoxyl groups, reflects the classic 1,3-diaxial repulsion (Elial & Wilson, 1984), the corresponding angle, C1—C6—C5, bearing these two substituents equatorially on the C1 and C5 atoms, being substantially smaller. The fact that angle C4—C5—C6 is significantly larger than its corresponding angle C2—C1—C6 is a reflection of the asymmetric skeletal distortion associated with the noted above. The mean endocyclic angle [111.9 (3)°] is identical, within error, to the mean value [111.4 (4)°] of those in trans-1,4-cyclohexanedicarboxylic (Dunitz & Strickler, 1966; Von Luger et al., 1972). The structural deformation caused by the 1,3-diaxial carbomethoxyl groups in (I) is also quite evident from a comparison of the related torsion angles, e.g. C7—C1—C2—C11 is much larger than C15—C4—C5—C19, while C3—C4—C5—C6 is much smaller than C6—C1—C2—C3; C1—C2—C3—C4 is much larger than C2—C3—C4—C5; and C2—C1—C6—C5 is substantially larger than C4—C5—C6—C1.

Experimental top

A mixture of tetramethyl 1,4-cyclohexadiene-1,2,4,5-tetracarboxylate, (II) (0.817 g, 2.6 mmol), and 10% palladium (42 mg) on carbon in methanol (60 ml) was shaken at room temperature for 18 h in a bottle attached to a hydrogenator maintaining a pressure of 80 p.s.i. of hydrogen. The resulting mixture was diluted with ethyl acetate (150 ml), filtered through Celite, and the solids were carefully washed with ethyl acetate. The combined filtrates were concentrated and column-chromatographed on silica gel, using a gradient mixture of hexane and diethyl ether as eluent, to give 0.752 g (91% yield) of compound (I). Recrystallization from diethyl ether provided long colorless needles, m.p. 388–391 K, used for the X-ray study.

Refinement top

The rotational orientations of the methyl groups were refined by the circular Fourier method available in SHELXL97 (Sheldrick, 1997). C—H riding distances for methyl, methylene and methine groups were fixed at 0.96, 0.97 and 0.98 Å, respectively. Uiso values for H atoms were calculated as B x Uiso of their associated C atoms where B = 1.5 for methyl H atoms and B = 1.2 for methylene and methine H atoms. All H atoms are riding.

Computing details top

Data collection: MSC/AFC Diffractometer Control Software (Molecular Structure Corporation, 1996); cell refinement: MSC/AFC Diffractometer Control Software; data reduction: PROCESS in TEXSAN (Molecular Structure Corporation, 1997); program(s) used to solve structure: SIR92 (Burla et al., 1989); program(s) used to refine structure: LS in TEXSAN and SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP in TEXSAN (Johnson, 1965); software used to prepare material for publication: TEXSAN, SHELXL97, and PLATON (Spek, 2000).

Figures top
[Figure 1] Fig. 1. The molecular structure and atom numbering scheme for (I) with displacement ellipsoids at the 30% probability level.
Cis,cis,cis-Tetramethyl 1,2,4,5-cyclohexanetetracarboxylate top
Crystal data top
C14H20O8Dx = 1.341 Mg m3
Mr = 316.3Melting point = 388–391 K
Monoclinic, C2/cMo Kα radiation, λ = 0.71069 Å
a = 18.6901 (19) ÅCell parameters from 25 reflections
b = 10.031 (2) Åθ = 7.7–11.9°
c = 17.781 (2) ŵ = 0.11 mm1
β = 109.910 (8)°T = 296 K
V = 3134.3 (9) Å3Plate, colorless
Z = 80.49 × 0.30 × 0.05 mm
F(000) = 1344
Data collection top
Rigaku AFC-5S
diffractometer
Rint = 0.027
Radiation source: X-ray tubeθmax = 25.0°, θmin = 2.3°
Graphite monochromatorh = 2220
ω (rate 2° min–1 in ω) scansk = 011
2864 measured reflectionsl = 021
2766 independent reflections3 standard reflections every 100 reflections
1039 reflections with I > 2σ(I) intensity decay: 0.1%
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)] = 0.040Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.128H-atom parameters constrained
S = 0.96 w = 1/[σ2(Fo2) + (0.0431P)2]
where P = (Fo2 + 2Fc2)/3
2766 reflections(Δ/σ)max < 0.001
203 parametersΔρmax = 0.17 e Å3
0 restraintsΔρmin = 0.15 e Å3
Crystal data top
C14H20O8V = 3134.3 (9) Å3
Mr = 316.3Z = 8
Monoclinic, C2/cMo Kα radiation
a = 18.6901 (19) ŵ = 0.11 mm1
b = 10.031 (2) ÅT = 296 K
c = 17.781 (2) Å0.49 × 0.30 × 0.05 mm
β = 109.910 (8)°
Data collection top
Rigaku AFC-5S
diffractometer
Rint = 0.027
2864 measured reflections3 standard reflections every 100 reflections
2766 independent reflections intensity decay: 0.1%
1039 reflections with I > 2σ(I)
Refinement top
R[F2 > 2σ(F2)] = 0.0400 restraints
wR(F2) = 0.128H-atom parameters constrained
S = 0.96Δρmax = 0.17 e Å3
2766 reflectionsΔρmin = 0.15 e Å3
203 parameters
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
O80.11054 (16)0.1136 (4)0.56690 (15)0.0879 (10)
O90.02716 (15)0.2089 (3)0.61506 (14)0.0625 (8)
O120.09483 (14)0.0362 (2)0.72745 (14)0.0563 (7)
O130.11135 (14)0.0156 (2)0.85442 (13)0.0535 (7)
O160.27583 (15)0.0498 (3)0.86392 (14)0.0602 (7)
O170.29319 (15)0.0627 (3)0.97697 (13)0.0624 (7)
O200.38150 (15)0.0664 (3)0.73795 (16)0.0756 (9)
O210.41924 (14)0.1285 (3)0.86585 (15)0.0627 (7)
C10.15544 (19)0.2073 (4)0.69913 (18)0.0455 (9)
C20.1321 (2)0.1879 (3)0.77329 (19)0.0435 (9)
C30.19406 (19)0.2468 (3)0.84617 (19)0.0471 (9)
C40.2747 (2)0.1898 (3)0.86159 (19)0.0453 (9)
C50.29473 (19)0.1919 (3)0.78425 (18)0.0442 (9)
C60.23125 (19)0.1406 (3)0.71033 (19)0.0475 (9)
C70.0969 (2)0.1686 (4)0.6203 (2)0.0550 (10)
C100.0329 (2)0.1848 (5)0.5395 (2)0.0818 (14)
C110.11153 (19)0.0423 (4)0.7808 (2)0.0422 (9)
C140.0907 (2)0.1193 (4)0.8671 (2)0.0645 (11)
C150.28147 (19)0.0543 (4)0.8989 (2)0.0429 (9)
C180.2939 (3)0.0608 (4)1.0189 (2)0.0824 (14)
C190.3681 (2)0.1210 (4)0.7916 (2)0.0515 (10)
C220.4913 (2)0.0636 (4)0.8779 (3)0.0790 (13)
H10.16390.30320.69570.055*
H20.08590.24060.76490.052*
H3a0.18010.23120.89320.056*
H3b0.19560.34250.83900.056*
H40.31090.24840.90030.054*
H50.30240.28570.77370.053*
H6a0.24520.15660.66330.057*
H6b0.22600.04520.71530.057*
H10a0.01930.22390.49700.123*
H10b0.07930.22410.54070.123*
H10c0.03980.09050.53090.123*
H14a0.03920.13640.83330.097*
H14b0.09480.13040.92210.097*
H14c0.12420.18080.85430.097*
H18a0.24250.08951.00930.124*
H18b0.31910.04751.07520.124*
H18c0.32040.12761.00000.124*
H22a0.48320.03020.86770.118*
H22b0.52430.07700.93210.118*
H22c0.51440.10080.84200.118*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O80.0680 (19)0.151 (3)0.0475 (16)0.006 (2)0.0231 (15)0.0246 (19)
O90.0573 (18)0.075 (2)0.0506 (16)0.0103 (15)0.0120 (15)0.0113 (14)
O120.0705 (18)0.0548 (17)0.0447 (15)0.0137 (15)0.0211 (14)0.0047 (14)
O130.0712 (19)0.0508 (17)0.0473 (15)0.0021 (14)0.0318 (14)0.0031 (12)
O160.090 (2)0.0388 (15)0.0590 (16)0.0053 (15)0.0349 (15)0.0023 (14)
O170.089 (2)0.0609 (18)0.0378 (14)0.0041 (16)0.0215 (13)0.0001 (13)
O200.064 (2)0.101 (2)0.0680 (19)0.0008 (17)0.0304 (16)0.0218 (17)
O210.0474 (16)0.0756 (19)0.0604 (17)0.0016 (15)0.0122 (14)0.0064 (15)
C10.054 (3)0.043 (2)0.040 (2)0.0008 (19)0.0166 (18)0.0047 (18)
C20.052 (2)0.035 (2)0.047 (2)0.0084 (19)0.0219 (19)0.0031 (18)
C30.063 (3)0.038 (2)0.045 (2)0.000 (2)0.0245 (19)0.0044 (18)
C40.055 (2)0.042 (2)0.040 (2)0.004 (2)0.0176 (18)0.0067 (17)
C50.054 (2)0.035 (2)0.044 (2)0.0024 (19)0.0168 (19)0.0002 (17)
C60.057 (2)0.052 (2)0.0396 (19)0.001 (2)0.0231 (18)0.0015 (18)
C70.059 (3)0.065 (3)0.044 (2)0.000 (2)0.021 (2)0.010 (2)
C100.066 (3)0.121 (4)0.050 (2)0.001 (3)0.009 (2)0.022 (3)
C110.041 (2)0.049 (3)0.040 (2)0.0053 (19)0.0196 (18)0.004 (2)
C140.077 (3)0.057 (3)0.063 (2)0.006 (2)0.028 (2)0.016 (2)
C150.043 (2)0.045 (2)0.042 (2)0.0002 (19)0.0175 (17)0.0028 (19)
C180.106 (4)0.082 (3)0.056 (3)0.001 (3)0.024 (3)0.030 (2)
C190.055 (3)0.046 (2)0.058 (3)0.013 (2)0.026 (2)0.004 (2)
C220.052 (3)0.086 (3)0.091 (3)0.001 (3)0.014 (2)0.001 (3)
Geometric parameters (Å, º) top
C1—C21.536 (4)C5—C191.511 (5)
C2—C31.532 (4)C1—H10.9800
C3—C41.547 (4)C2—H20.9800
C4—C51.543 (4)C3—H3a0.9700
C5—C61.529 (4)C3—H3b0.9700
C1—C61.517 (5)C4—H40.9800
O8—C71.197 (4)C5—H50.9800
O9—C71.338 (4)C6—H6a0.9700
O9—C101.447 (4)C6—H6b0.9700
O12—C111.191 (4)C10—H10a0.9600
O13—C111.337 (4)C10—H10b0.9600
O13—C141.446 (4)C10—H10c0.9600
O16—C151.201 (4)C14—H14a0.9600
O17—C151.332 (4)C14—H14b0.9600
O17—C181.444 (4)C14—H14c0.9600
O20—C191.197 (4)C18—H18a0.9600
O21—C191.343 (4)C18—H18b0.9600
O21—C221.445 (4)C18—H18c0.9600
C1—C71.506 (5)C22—H22a0.9600
C2—C111.527 (5)C22—H22b0.9600
C4—C151.499 (5)C22—H22c0.9600
C2—C1—C6110.9 (3)C2—C3—H3b108.6
C1—C2—C3108.9 (3)C4—C3—H3b108.6
C2—C3—C4114.6 (3)H3a—C3—H3b107.6
C3—C4—C5110.7 (3)C15—C4—H4107.4
C4—C5—C6114.1 (3)C5—C4—H4107.4
C1—C6—C5112.4 (3)C3—C4—H4107.4
C7—O9—C10116.3 (3)C19—C5—H5106.3
C11—O13—C14115.5 (3)C6—C5—H5106.3
C15—O17—C18116.9 (3)C4—C5—H5106.3
C19—O21—C22115.8 (3)C1—C6—H6a109.1
C7—C1—C6111.0 (3)C5—C6—H6a109.1
C7—C1—C2116.0 (3)C1—C6—H6b109.1
C11—C2—C3115.8 (3)C5—C6—H6b109.1
C11—C2—C1110.5 (3)H6a—C6—H6b107.9
C15—C4—C5113.5 (3)O9—C10—H10a109.5
C15—C4—C3110.1 (3)O9—C10—H10b109.5
C19—C5—C6109.4 (3)H10a—C10—H10b109.5
C19—C5—C4113.9 (3)O9—C10—H10c109.5
O8—C7—O9123.4 (4)H10a—C10—H10c109.5
O8—C7—C1125.0 (4)H10b—C10—H10c109.5
O12—C11—O13124.1 (3)O13—C14—H14a109.5
O12—C11—C2124.6 (3)O13—C14—H14b109.5
O13—C11—C2111.3 (3)H14a—C14—H14b109.5
O9—C7—C1111.6 (3)O13—C14—H14c109.5
O16—C15—O17123.3 (3)H14a—C14—H14c109.5
O16—C15—C4125.4 (3)H14b—C14—H14c109.5
O17—C15—C4111.3 (3)O17—C18—H18a109.5
O20—C19—O21122.5 (4)O17—C18—H18b109.5
O20—C19—C5125.2 (4)H18a—C18—H18b109.5
O21—C19—C5112.3 (3)O17—C18—H18c109.5
C7—C1—H1106.1H18a—C18—H18c109.5
C6—C1—H1106.1H18b—C18—H18c109.5
C2—C1—H1106.1O21—C22—H22a109.5
C11—C2—H2107.1O21—C22—H22b109.5
C3—C2—H2107.1H22a—C22—H22b109.5
C1—C2—H2107.1O21—C22—H22c109.5
C2—C3—H3a108.6H22a—C22—H22c109.5
C4—C3—H3a108.6H22b—C22—H22c109.5
C7—C1—C2—C1158.2 (4)C6—C1—C7—O9170.0 (3)
C15—C4—C5—C1947.9 (4)C2—C1—C7—O942.3 (4)
C2—C3—C4—C549.4 (4)C14—O13—C11—O121.3 (5)
C2—C1—C6—C557.2 (4)C14—O13—C11—C2178.5 (3)
C3—C4—C5—C645.6 (4)C3—C2—C11—O12144.1 (3)
C6—C1—C2—C358.7 (4)C1—C2—C11—O1219.7 (5)
C1—C2—C3—C456.1 (4)C3—C2—C11—O1338.7 (4)
C11—C2—C3—C469.1 (4)C1—C2—C11—O13163.0 (3)
C2—C3—C4—C1576.9 (3)C18—O17—C15—O164.2 (5)
C19—C5—C6—C1179.9 (3)C18—O17—C15—C4174.6 (3)
C7—C1—C6—C5172.3 (3)C5—C4—C15—O1625.5 (5)
C4—C5—C6—C150.9 (4)C3—C4—C15—O1699.2 (4)
C6—C1—C2—C1169.5 (4)C5—C4—C15—O17155.7 (3)
C7—C1—C2—C3173.5 (3)C3—C4—C15—O1779.5 (3)
C3—C4—C5—C19172.3 (3)C22—O21—C19—O201.4 (5)
C15—C4—C5—C678.8 (4)C22—O21—C19—C5179.8 (3)
C10—O9—C7—O81.1 (5)C6—C5—C19—O2021.2 (5)
C10—O9—C7—C1176.0 (3)C4—C5—C19—O20150.3 (4)
C6—C1—C7—O813.0 (5)C6—C5—C19—O21160.4 (3)
C2—C1—C7—O8140.7 (4)C4—C5—C19—O2131.3 (4)

Experimental details

Crystal data
Chemical formulaC14H20O8
Mr316.3
Crystal system, space groupMonoclinic, C2/c
Temperature (K)296
a, b, c (Å)18.6901 (19), 10.031 (2), 17.781 (2)
β (°) 109.910 (8)
V3)3134.3 (9)
Z8
Radiation typeMo Kα
µ (mm1)0.11
Crystal size (mm)0.49 × 0.30 × 0.05
Data collection
DiffractometerRigaku AFC-5S
diffractometer
Absorption correction
No. of measured, independent and
observed [I > 2σ(I)] reflections
2864, 2766, 1039
Rint0.027
(sin θ/λ)max1)0.595
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.040, 0.128, 0.96
No. of reflections2766
No. of parameters203
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.17, 0.15

Computer programs: MSC/AFC Diffractometer Control Software (Molecular Structure Corporation, 1996), MSC/AFC Diffractometer Control Software, PROCESS in TEXSAN (Molecular Structure Corporation, 1997), SIR92 (Burla et al., 1989), LS in TEXSAN and SHELXL97 (Sheldrick, 1997), ORTEP in TEXSAN (Johnson, 1965), TEXSAN, SHELXL97, and PLATON (Spek, 2000).

Selected geometric parameters (Å, º) top
C1—C21.536 (4)C4—C51.543 (4)
C2—C31.532 (4)C5—C61.529 (4)
C3—C41.547 (4)C1—C61.517 (5)
C2—C1—C6110.9 (3)C3—C4—C5110.7 (3)
C1—C2—C3108.9 (3)C4—C5—C6114.1 (3)
C2—C3—C4114.6 (3)C1—C6—C5112.4 (3)
C7—C1—C2—C1158.2 (4)C1—C2—C3—C456.1 (4)
C15—C4—C5—C1947.9 (4)C11—C2—C3—C469.1 (4)
C2—C3—C4—C549.4 (4)C2—C3—C4—C1576.9 (3)
C2—C1—C6—C557.2 (4)C19—C5—C6—C1179.9 (3)
C3—C4—C5—C645.6 (4)C7—C1—C6—C5172.3 (3)
C6—C1—C2—C358.7 (4)C4—C5—C6—C150.9 (4)
 

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