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The structure of the title mol­ecule, C21H20Cl2O2, reveals a chair conformation for the cyclo­hexane ring in which all the substituents occupy equatorial positions.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536802015283/ci6143sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600536802015283/ci6143Isup2.hkl
Contains datablock I

CCDC reference: 198329

Key indicators

  • Single-crystal X-ray study
  • T = 293 K
  • Mean [sigma](C-C) = 0.007 Å
  • R factor = 0.042
  • wR factor = 0.100
  • Data-to-parameter ratio = 8.4

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry

General Notes

REFLT_03 From the CIF: _diffrn_reflns_theta_max 24.98 From the CIF: _reflns_number_total 1904 Count of symmetry unique reflns 1906 Completeness (_total/calc) 99.90% TEST3: Check Friedels for noncentro structure Estimate of Friedel pairs measured 0 Fraction of Friedel pairs measured 0.000 Are heavy atom types Z>Si present yes WARNING: Large fraction of Friedel related reflns may be needed to determine absolute structure

Comment top

During attempts to prepare a pyran derivative by the Michael condensation of diethyl ketone and o-chlorobenzaldehyde, an unexpected product, the title compound, (I), was obtained as a minor product. The present investigation was undertaken to ascertain the structure and conformation of (I), since they cannot be assigned conclusively from 1H NMR data.

The cyclohexane ring is in a chair conformation, as shown by the torsion angles (Table 1) around the C—C bonds involving the six C atoms (C1–C6). The torsion angles deviate from the angle of 56° expected for a perfect chair conformation (Kalsi, 1997) as a result of the sp2-hybridized atom C1. The bond lengths and angles within the cyclohexane ring are in the ranges 1.503 (6)—1.551 (6) Å and 106.6 (3)–116.9 (4)°, respectively. The equatorial orientations of all the substituents are confirmed by the torsion angles of about 180° formed by the external atom and the other three ring atoms. The dihedral angle between the planes of the phenyl rings is 61.9 (2)°. The chair conformation observed in (I) is comparable to that observed in the thioketal of N-methyl-2,6-diphenyl-3-isopropylpiperdin-4-one (Sujatha, 1995), but contrasts with the twist-boat conformation of the N-nitroso derivative of 2,6-bis(2-chlorophenyl-3,5-dimethylpiperidin-4-one (Sukumar et al., 1993). Atoms O10, C9, C4, O7 and C1 are coplanar with the maximum deviation being 0.014 (2) Å for O10; the molecule is nearly symmetrical with respect to the above plane.

The crystal structure is stabilized by C—H···O interactions, the most significant of which are (C9)H9···O7(−1 + x, y, z) and (C16)H16···O7(1 − x, 0.5 + y, 0.5 − z) with H···O distances of 2.45 and 2.42 Å, and C—H···O angles of 130.5 and 146.5°, respectively, around the corresponding H atoms. The former interactions contribute to the chain formation along the a axis; the chains are interlinked by the latter interactions. Another intermolecular interaction prevails between atoms C4 and O10(0.5 + x, 0.5 − y, −z) through atom H4, with a distance of 2.56 Å with an angle of 161.2° around H4. The formation of (I), although unexpected, can be explained by the condensation of the dibenzylideneacetone derivative formed in situ with the acetaldehyde present in ethanol.

Experimental top

The title compound was obtained by the reaction of diethyl ketone with o-chlorobenzaldehyde in 80% ethanol. Diffraction quality crystals were obtained by recrystallization from ethanol. 1H NMR (CDCl3, p.p.m.): δ = 0.92 (d, 6H, J = 6.3), 2.87 (m, 2H), 3.93 (t, 2H, J = 12.0), 3.38 (dt, 1H, 3J = 4.8, 2J = 12.2), 7.1–7.8 (m, 8H), 9.21 (d, 1H, J = 4.5).

Refinement top

Since the Friedel pairs were not measured during the data collection, we were unable to determine the absolute structure. All the H atoms were fixed geometrically and allowed to ride on the parent C atoms, with aromatic C—H = 0.93 Å, tertiary C—H = 0.97 Å and methyl C—H = 0.96 Å. The displacement parameters Uiso(H) were set at 1.5 Ueq(C) for the methyl H atoms and at 1.2 Ueq(C) for other H atoms.

Computing details top

Data collection: CAD-4 Software (Enraf-Nonius, 1989); cell refinement: CAD-4 Software; data reduction: MolEN (Fair, 1990); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ZORTEP (Zsolnai, 1997); software used to prepare material for publication: SHELXL97.

Figures top
[Figure 1] Fig. 1. The molecular structure of (I), showing 30% probability displacement ellipsoids and the atom-numbering scheme.
2,6-dimethyl-3,5-(3-chlorophenyl)-4-formyl-cyclohexan-1-one top
Crystal data top
C21H20Cl2O2F(000) = 784
Mr = 375.27Dx = 1.328 Mg m3
Orthorhombic, P212121Mo Kα radiation, λ = 0.71069 Å
Hall symbol: P 2ac 2abCell parameters from 25 reflections
a = 7.635 (2) Åθ = 2–12°
b = 12.1814 (15) ŵ = 0.36 mm1
c = 20.175 (4) ÅT = 293 K
V = 1876.4 (7) Å3Translucent block, colourless
Z = 40.2 × 0.2 × 0.1 mm
Data collection top
Enraf-Nonius CAD-4
diffractometer
1399 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.000
Graphite monochromatorθmax = 25.0°, θmin = 2.0°
ω–2θ scansh = 09
Absorption correction: ψ scan
(North et al., 1968)
k = 014
Tmin = 0.982, Tmax = 0.999l = 023
1904 measured reflections3 standard reflections every 100 reflections
1904 independent reflections intensity decay: none
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)] = 0.042Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.100H-atom parameters constrained
S = 1.15 w = 1/[σ2(Fo2) + (0.0344P)2 + 0.6059P]
where P = (Fo2 + 2Fc2)/3
1904 reflections(Δ/σ)max < 0.001
226 parametersΔρmax = 0.18 e Å3
0 restraintsΔρmin = 0.18 e Å3
Crystal data top
C21H20Cl2O2V = 1876.4 (7) Å3
Mr = 375.27Z = 4
Orthorhombic, P212121Mo Kα radiation
a = 7.635 (2) ŵ = 0.36 mm1
b = 12.1814 (15) ÅT = 293 K
c = 20.175 (4) Å0.2 × 0.2 × 0.1 mm
Data collection top
Enraf-Nonius CAD-4
diffractometer
1399 reflections with I > 2σ(I)
Absorption correction: ψ scan
(North et al., 1968)
Rint = 0.000
Tmin = 0.982, Tmax = 0.9993 standard reflections every 100 reflections
1904 measured reflections intensity decay: none
1904 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0420 restraints
wR(F2) = 0.100H-atom parameters constrained
S = 1.15Δρmax = 0.18 e Å3
1904 reflectionsΔρmin = 0.18 e Å3
226 parameters
Special details top

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
C10.8270 (5)0.1378 (3)0.1271 (2)0.0502 (10)
C20.7519 (5)0.2517 (3)0.13446 (19)0.0492 (10)
H20.77350.29210.09320.059*
C30.5512 (5)0.2378 (3)0.14281 (18)0.0468 (10)
H30.53250.19290.18250.056*
C40.4734 (5)0.1736 (3)0.0836 (2)0.0446 (10)
H40.50080.21240.04230.054*
C50.5565 (5)0.0586 (3)0.0818 (2)0.0474 (10)
H50.53850.02550.12550.057*
C60.7571 (5)0.0690 (3)0.0712 (2)0.0510 (11)
H60.77770.10800.02950.061*
O70.9329 (4)0.1020 (2)0.16662 (14)0.0604 (8)
C80.8348 (7)0.3150 (4)0.1910 (2)0.0731 (14)
H8A0.95840.32170.18340.110*
H8B0.81510.27650.23190.110*
H8C0.78330.38670.19360.110*
C90.2779 (6)0.1650 (3)0.0912 (2)0.0497 (10)
H90.23490.12870.12830.060*
O100.1740 (4)0.2016 (3)0.05289 (15)0.0780 (10)
C110.8479 (7)0.0420 (4)0.0675 (3)0.0759 (15)
H11A0.97120.03130.06090.114*
H11B0.80070.08340.03120.114*
H11C0.82910.08130.10810.114*
C120.4603 (5)0.3460 (3)0.1545 (2)0.0520 (10)
C130.4850 (6)0.4343 (4)0.1119 (2)0.0652 (13)
H130.55500.42510.07460.078*
C140.4091 (8)0.5351 (4)0.1233 (3)0.0858 (17)
H140.42960.59320.09450.103*
C150.3021 (8)0.5491 (5)0.1778 (3)0.0923 (19)
H150.25160.61730.18600.111*
C160.2702 (8)0.4639 (5)0.2197 (3)0.0841 (17)
H160.19610.47340.25590.101*
C170.3484 (6)0.3629 (4)0.2084 (2)0.0610 (12)
Cl180.30319 (19)0.25791 (13)0.26360 (5)0.0876 (5)
C190.4697 (6)0.0153 (3)0.0319 (2)0.0499 (10)
C200.3628 (6)0.1039 (3)0.0498 (2)0.0607 (12)
C210.2843 (7)0.1714 (4)0.0038 (3)0.0721 (14)
H210.21450.22970.01760.087*
C220.3096 (8)0.1524 (4)0.0621 (3)0.0839 (16)
H220.25740.19780.09340.101*
C230.4128 (8)0.0655 (5)0.0822 (3)0.0816 (16)
H230.43010.05240.12710.098*
C240.4906 (6)0.0021 (4)0.0357 (2)0.0650 (13)
H240.55860.06080.05000.078*
Cl250.3244 (2)0.13281 (11)0.13299 (7)0.0888 (5)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.034 (2)0.057 (2)0.060 (2)0.006 (2)0.002 (2)0.011 (2)
C20.043 (2)0.051 (2)0.053 (2)0.004 (2)0.0024 (18)0.004 (2)
C30.046 (2)0.050 (2)0.044 (2)0.001 (2)0.0023 (18)0.000 (2)
C40.041 (2)0.047 (2)0.046 (2)0.000 (2)0.0023 (18)0.006 (2)
C50.046 (2)0.047 (2)0.049 (2)0.004 (2)0.003 (2)0.007 (2)
C60.043 (2)0.049 (2)0.060 (2)0.003 (2)0.003 (2)0.000 (2)
O70.0450 (17)0.0674 (19)0.0687 (18)0.0000 (16)0.0039 (16)0.0130 (16)
C80.062 (3)0.072 (3)0.085 (3)0.003 (3)0.013 (3)0.013 (3)
C90.050 (3)0.051 (2)0.048 (2)0.000 (2)0.003 (2)0.003 (2)
O100.0513 (19)0.104 (3)0.079 (2)0.005 (2)0.0113 (18)0.028 (2)
C110.063 (3)0.067 (3)0.097 (4)0.016 (3)0.005 (3)0.013 (3)
C120.046 (2)0.056 (3)0.053 (2)0.005 (2)0.001 (2)0.014 (2)
C130.059 (3)0.056 (3)0.080 (3)0.002 (3)0.005 (3)0.002 (2)
C140.088 (4)0.050 (3)0.119 (5)0.004 (3)0.011 (4)0.004 (3)
C150.073 (4)0.070 (4)0.134 (5)0.013 (3)0.016 (4)0.047 (4)
C160.072 (4)0.092 (4)0.088 (4)0.001 (3)0.001 (3)0.042 (3)
C170.055 (3)0.070 (3)0.057 (2)0.002 (3)0.007 (2)0.021 (2)
Cl180.0821 (9)0.1231 (11)0.0576 (6)0.0011 (10)0.0159 (7)0.0000 (7)
C190.051 (3)0.041 (2)0.058 (2)0.006 (2)0.005 (2)0.003 (2)
C200.065 (3)0.046 (2)0.071 (3)0.008 (2)0.010 (3)0.002 (2)
C210.068 (3)0.048 (3)0.100 (4)0.005 (3)0.014 (3)0.010 (3)
C220.092 (4)0.076 (4)0.084 (4)0.006 (4)0.019 (3)0.029 (3)
C230.098 (4)0.087 (4)0.060 (3)0.012 (4)0.012 (3)0.009 (3)
C240.069 (3)0.068 (3)0.058 (3)0.006 (3)0.004 (2)0.006 (2)
Cl250.1037 (11)0.0784 (8)0.0842 (8)0.0309 (9)0.0067 (9)0.0221 (7)
Geometric parameters (Å, º) top
C1—O71.217 (4)C11—H11C0.96
C1—C61.503 (6)C12—C131.389 (6)
C1—C21.509 (6)C12—C171.399 (6)
C2—C81.515 (6)C13—C141.377 (6)
C2—C31.551 (5)C13—H130.93
C2—H20.98C14—C151.380 (8)
C3—C121.509 (6)C14—H140.93
C3—C41.546 (5)C15—C161.361 (7)
C3—H30.98C15—H150.93
C4—C91.505 (6)C16—C171.386 (7)
C4—C51.538 (5)C16—H160.93
C4—H40.98C17—Cl181.730 (5)
C5—C191.504 (6)C19—C241.389 (6)
C5—C61.551 (6)C19—C201.400 (6)
C5—H50.98C20—C211.378 (6)
C6—C111.521 (6)C20—Cl251.739 (5)
C6—H60.98C21—C221.362 (7)
C8—H8A0.96C21—H210.93
C8—H8B0.96C22—C231.381 (7)
C8—H8C0.96C22—H220.93
C9—O101.193 (4)C23—C241.382 (6)
C9—H90.93C23—H230.93
C11—H11A0.96C24—H240.93
C11—H11B0.96
O7—C1—C6121.8 (4)C6—C11—H11A109.5
O7—C1—C2121.2 (4)C6—C11—H11B109.5
C6—C1—C2116.9 (4)H11A—C11—H11B109.5
C1—C2—C8112.5 (4)C6—C11—H11C109.5
C1—C2—C3106.6 (3)H11A—C11—H11C109.5
C8—C2—C3112.7 (4)H11B—C11—H11C109.5
C1—C2—H2108.3C13—C12—C17116.8 (4)
C8—C2—H2108.3C13—C12—C3121.2 (4)
C3—C2—H2108.3C17—C12—C3122.0 (4)
C12—C3—C4112.7 (3)C14—C13—C12122.0 (5)
C12—C3—C2112.1 (3)C14—C13—H13119.0
C4—C3—C2110.5 (3)C12—C13—H13119.0
C12—C3—H3107.1C13—C14—C15119.5 (5)
C4—C3—H3107.1C13—C14—H14120.2
C2—C3—H3107.1C15—C14—H14120.2
C9—C4—C5110.4 (3)C16—C15—C14120.4 (5)
C9—C4—C3109.7 (3)C16—C15—H15119.8
C5—C4—C3108.7 (3)C14—C15—H15119.8
C9—C4—H4109.3C15—C16—C17119.9 (5)
C5—C4—H4109.3C15—C16—H16120.1
C3—C4—H4109.3C17—C16—H16120.1
C19—C5—C4112.3 (3)C16—C17—C12121.4 (5)
C19—C5—C6113.0 (4)C16—C17—Cl18117.7 (4)
C4—C5—C6109.6 (3)C12—C17—Cl18120.9 (4)
C19—C5—H5107.2C24—C19—C20116.0 (4)
C4—C5—H5107.2C24—C19—C5121.0 (4)
C6—C5—H5107.2C20—C19—C5123.0 (4)
C1—C6—C11111.8 (4)C21—C20—C19122.6 (4)
C1—C6—C5107.1 (4)C21—C20—Cl25117.1 (4)
C11—C6—C5112.6 (4)C19—C20—Cl25120.3 (3)
C1—C6—H6108.4C22—C21—C20119.6 (5)
C11—C6—H6108.4C22—C21—H21120.2
C5—C6—H6108.4C20—C21—H21120.2
C2—C8—H8A109.5C21—C22—C23119.9 (5)
C2—C8—H8B109.5C21—C22—H22120.1
H8A—C8—H8B109.5C23—C22—H22120.1
C2—C8—H8C109.5C22—C23—C24120.2 (5)
H8A—C8—H8C109.5C22—C23—H23119.9
H8B—C8—H8C109.5C24—C23—H23119.9
O10—C9—C4124.6 (4)C23—C24—C19121.7 (5)
O10—C9—H9117.7C23—C24—H24119.1
C4—C9—H9117.7C19—C24—H24119.1
O7—C1—C2—C85.0 (5)C4—C3—C12—C17107.6 (4)
C6—C1—C2—C8178.5 (4)C2—C3—C12—C17127.0 (4)
O7—C1—C2—C3119.0 (4)C17—C12—C13—C142.4 (7)
C6—C1—C2—C357.4 (5)C3—C12—C13—C14177.2 (4)
C1—C2—C3—C12176.9 (3)C12—C13—C14—C151.3 (8)
C8—C2—C3—C1252.9 (5)C13—C14—C15—C160.7 (9)
C1—C2—C3—C456.5 (4)C14—C15—C16—C171.4 (9)
C8—C2—C3—C4179.6 (3)C15—C16—C17—C120.1 (8)
C12—C3—C4—C951.4 (4)C15—C16—C17—Cl18179.8 (4)
C2—C3—C4—C9177.7 (4)C13—C12—C17—C161.8 (7)
C12—C3—C4—C5172.2 (3)C3—C12—C17—C16177.9 (4)
C2—C3—C4—C561.5 (4)C13—C12—C17—Cl18178.3 (3)
C9—C4—C5—C1951.3 (5)C3—C12—C17—Cl182.0 (6)
C3—C4—C5—C19171.7 (3)C4—C5—C19—C2470.6 (5)
C9—C4—C5—C6177.8 (3)C6—C5—C19—C2454.1 (5)
C3—C4—C5—C661.8 (4)C4—C5—C19—C20108.7 (4)
O7—C1—C6—C115.7 (6)C6—C5—C19—C20126.6 (4)
C2—C1—C6—C11177.8 (4)C24—C19—C20—C210.9 (7)
O7—C1—C6—C5118.0 (4)C5—C19—C20—C21179.8 (4)
C2—C1—C6—C558.4 (5)C24—C19—C20—Cl25179.1 (3)
C19—C5—C6—C1176.0 (3)C5—C19—C20—Cl250.1 (6)
C4—C5—C6—C157.9 (4)C19—C20—C21—C220.2 (7)
C19—C5—C6—C1152.7 (5)Cl25—C20—C21—C22179.8 (4)
C4—C5—C6—C11178.9 (4)C20—C21—C22—C230.3 (8)
C5—C4—C9—O10121.3 (5)C21—C22—C23—C240.0 (8)
C3—C4—C9—O10118.9 (5)C22—C23—C24—C190.7 (8)
C4—C3—C12—C1372.8 (5)C20—C19—C24—C231.2 (7)
C2—C3—C12—C1352.7 (5)C5—C19—C24—C23179.5 (4)

Experimental details

Crystal data
Chemical formulaC21H20Cl2O2
Mr375.27
Crystal system, space groupOrthorhombic, P212121
Temperature (K)293
a, b, c (Å)7.635 (2), 12.1814 (15), 20.175 (4)
V3)1876.4 (7)
Z4
Radiation typeMo Kα
µ (mm1)0.36
Crystal size (mm)0.2 × 0.2 × 0.1
Data collection
DiffractometerEnraf-Nonius CAD-4
diffractometer
Absorption correctionψ scan
(North et al., 1968)
Tmin, Tmax0.982, 0.999
No. of measured, independent and
observed [I > 2σ(I)] reflections
1904, 1904, 1399
Rint0.000
(sin θ/λ)max1)0.594
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.042, 0.100, 1.15
No. of reflections1904
No. of parameters226
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.18, 0.18

Computer programs: CAD-4 Software (Enraf-Nonius, 1989), CAD-4 Software, MolEN (Fair, 1990), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), ZORTEP (Zsolnai, 1997), SHELXL97.

Selected torsion angles (º) top
C6—C1—C2—C357.4 (5)C3—C4—C5—C661.8 (4)
C1—C2—C3—C456.5 (4)C2—C1—C6—C558.4 (5)
C2—C3—C4—C561.5 (4)C4—C5—C6—C157.9 (4)
 

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