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The title compound, C12H10Cl4O2, has a pseudoasymmetric centre at the methyl-substituted carbon and, in the solid state, a boat-like conformation.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270100012361/gd1114sup1.cif
Contains datablocks global, III

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270100012361/gd1114IIIsup2.hkl
Contains datablock III

CCDC reference: 156171

Comment top

In our laboratory there is ongoing interest in the synthetic applications of the 2 + 2 cycloaddition of dichloroketene with olefins (Brady, 1981; Hyatt & Raynolds, 1994). This reaction is well known to be chemo- (Mehta & Rao, 1985; McMurry & Bosh, 1987; Dowd & Zhang, 1992), regio- (Ghosez et al., 1971; Hassner & Krepski, 1979; Deprés & Greene, 1989) and stereoselective (Hassner et al., 1971; Greene et al., 1985). The resulting α,α-dichlorocyclobutanones can be transformed into a variety of cyclopentanone (Deprés & Greene, 1980; Greene et al., 1983), lactone (Au-Yeung & Fleming, 1977; de Azevedo & Greene, 1995) and lactam (Nebois & Greene, 1996; Delair et al., 1999) naturally occurring and synthetic products.

We are currently examining the preparation of bicyclo[5.3.0]decane systems by 2 + 2 cycloaddition of dichloroketene with 7-substituted cycloheptatrienes, followed by ring expansion. The bicyclo[5.3.0]decane skeleton is frequently encountered in natural products, in particular the guaianolides (Connolly & Hill, 1991), which form one of the largest groups of sesquiterpene lactones (>500 known), many of which are significantly bioactive (Ando et al., 1994). This framework is of course also found in the azulenes (Mochalin & Porshnev, 1977). The reaction of one equivalent of dichloroketene with 7-methylcyclohepta-1,3,5-triene, (I), gives mostly the mono cycloadduct, (II), together with a small amount of the double addition product, (III), in the proportion 9:1. In the presence of excess dichloroketene, however, the starting triene and the mono adduct (II) both undergo regio- and diastereoselective cycloaddition to yield the title compound, (III), in good yield (see scheme). From the X-ray crystallographic elucidation of this compound (Fig. 1), the structure and stereochemistry of the mono adduct (II) are obvious. Compound (II) should be a useful intermediate for accessing a number of guaianolides and azulenes via compound (IV). Although double cycloaddition of dichloroketene with polyenes has previously been reported (see, for example, Mehta & Rao, 1985), to the best of our knowledge this is the first crystallographic determination of a bis-α,α-dichlorocyclobutanone. \sch

The interatomic distances and angles of (III) are in good agreement with those given by Allen et al. (1987). Although the molecule potentially exhibits mirror symmetry in the crystalline state, the two α,α-dichlorocyclobutanone units are not perfectly identical. However, the measured bond lengths and angles are extremely close and consequently only mean values will be cited in this discussion.

Each cyclobutane ring is fused to the seven-membered ring, either at C1 and C9 or at C3 and C6, with a C1—C9 (C3—C6) distance of 1.572 (6) Å. C11 (C4) of the carbonyl group [mean CO 1.189 (2) Å] is bound to C1 (C3) at a distance of 1.530 (2) Å and with a C11—C1—C9 (C4—C3—C6) angle of 88.3 (1)°. Situated 0.310 (2) Å above the plane defined by C11—C1—C9 (C4—C3—C6), the remaining carbon of the cyclobutanone, C10 (C5), is connected to C9 (C6) at a distance of 1.557 (5) Å and to C11 (C4) at a distance of 1.540 (2) Å, with C1—C9—C10 (C3—C6—C5) and C1—C11—C10 (C3—C4—C5) angles of 89.4 (2)° and 91.6 (2)°, respectively. The C9—C10—C11 (C6—C5—C4) angle is 88.5 (1)°. Finally, C10 (C5) is connected to the two Cl atoms at a distance of 1.771 (3) Å for the exo Cl3 (Cl1) and 1.758 (5) Å for the endo Cl4 (Cl2). A difference between these two bond lengths appears to be a general phenomenon, occurring as well in each of the nine α,α-dichlorocyclobutanone structures deposited in the Cambridge Structural Database (CSD; 1999).

It is of interest to compare certain other structural features of (III) with those of the compounds in the CSD. Compound (III) is the first example of an α,α-dichlorocyclobutanone fused to a seven-membered ring, the previously reported examples involving ring fusion with cyclohexanes (Nassimbeni et al., 1977), a cyclopentane (Glen et al., 1982), cyclopentenes (Gordon et al., 1981; Cocuzza & Boswell, 1985; Watson & Nagl, 1987; Dehmlow et al., 1995) and a bicyclo[3.1.0]hexene (Carpino et al., 1981). Notably, the ring-fusion bond length of 1.572 (6) Å in (III) is one of the longest, the others being 1.51 (3) and 1.557 (8) (cyclohexanes), 1.57 (cyclopentane), 1.55, 1.568 (3), 1.567 (5), 1.570 (3) and 1.575 (4) (cyclopentenes), and 1.53 Å (bicyclo[3.1.0] hexene). The dihedral angle in (III) between the α,α-dichlorocyclobutanone plane and the mean plane defined by the two C atoms at the ring fusion and their two non-cyclobutane neighbours [C2 (C2), C1 (C3), C9 (C6) and C8 (C7)] is 66.6 (1)°, whereas in the deposited α,α-dichlorocyclobutanones the values are, respectively, 53.7 (9), 73.3 (4), 65.8, 70.9, 60.1 (1), 69.9 (2), 77.73 (1), 75.2 (2) and 55.5°. Thus, the dihedral angle in (III) is unexceptional and apparently uninfluenced, somewhat surprisingly, by the size of the seven-membered ring.

The crystallographic determination reported in this paper, the first of not only a bis-α,α-dichlorocyclobutanone but also of a cycloheptane-containing adduct, nicely complements the few determinations of α,α-dichlorocyclobutanones presently available.

Experimental top

Compound (III) and the mono cycloadduct (II) were obtained as a mixture (9:1) by overnight stirring of (I) with trichloroacetyl chloride (3 equiv) and phosphorus oxychloride (3 equiv) in ether in the presence of zinc-copper couple, followed by the usual treatment. Compound (III) crystallized as colourless needles (m.p. 379–381 K) from the crude mixture (65% yield). No dichloroketene? Spectroscopic data: IR, cm−1: 3055, 1804, 1639; 1H NMR (CDCl3, 300 MHz, δ, p.p.m.): 1.33 (d, J = 6.4 Hz, 3H, H12), 2.69 (m, 1H, H2), 3.52 (pseudo t, J = 10.9 Hz, 2H, H1 and H3), 3.77 (pseudo d, J = 10.5 Hz, 2H, H6 and H9), 6.01 (s, 2H, H7 and H8); 13C NMR (CDCl3, 75 MHz, δ, p.p.m.): 17.6 (C12), 32.1 (C2), 48.1 (C6 and C9), 62.3 (C1 and C3), 87.3 (C5 and C10), 125.7 (C7 and C8), 193.4 (C4 and C11); MS (EI) m/z, M+ (isotopic distribution, %): 332 (6), 331 (9), 330 (46), 329 (20), 328 (100), 327 (20), 326 (78).

Refinement top

H atoms were located in difference Fourier syntheses and freely refined, with C—H distances of 0.90 (5)–1.02 (5) Å.

Computing details top

Data collection: CAD-4 Software (Enraf-Nonius, 1989); cell refinement: CAD-4 Software; data reduction: TEXSAN (Molecular Structure Corporation, 1992-1997); program(s) used to solve structure: SIR92 (Altomare et al., 1993); program(s) used to refine structure: TEXSAN; software used to prepare material for publication: TEXSAN.

Figures top
[Figure 1] Fig. 1. ORTEPII (Johnson, 1976) molecular diagram of (III). Displacement ellipsoids are shown at the 40% probability level and H atoms are drawn as small spheres of arbitrary radii.
(III) top
Crystal data top
C12H10Cl4O2F(000) = 664
Mr = 328.02Dx = 1.578 Mg m3
Monoclinic, P21/aMo Kα radiation, λ = 0.7107 Å
a = 10.320 (8) ÅCell parameters from 25 reflections
b = 12.390 (4) Åθ = 10.3–14.4°
c = 11.219 (2) ŵ = 0.85 mm1
β = 105.80 (4)°T = 293 K
V = 1380 (1) Å3Monoclinic prism, colourless
Z = 40.35 × 0.32 × 0.29 mm
Data collection top
Enraf-Nonius CAD-4
diffractometer
Rint = 0.011
Radiation source: X-ray tubeθmax = 30.0°, θmin = 2.1°
Graphite monochromatorh = 1414
ω scansk = 017
4160 measured reflectionsl = 015
3971 independent reflections2 standard reflections every 120 reflections
3675 reflections with I > 0 intensity decay: 5.5%
Refinement top
Refinement on F0 restraints
Least-squares matrix: full30 constraints
R[F2 > 2σ(F2)] = 0.066All H-atom parameters refined
wR(F2) = 0.050Weighting scheme based on measured s.u.'s w = 1/[σ2(Fo) + 0.00018|Fo|2]
S = 1.96(Δ/σ)max = 0.037
3675 reflectionsΔρmax = 0.18 e Å3
203 parametersΔρmin = 0.20 e Å3
Crystal data top
C12H10Cl4O2V = 1380 (1) Å3
Mr = 328.02Z = 4
Monoclinic, P21/aMo Kα radiation
a = 10.320 (8) ŵ = 0.85 mm1
b = 12.390 (4) ÅT = 293 K
c = 11.219 (2) Å0.35 × 0.32 × 0.29 mm
β = 105.80 (4)°
Data collection top
Enraf-Nonius CAD-4
diffractometer
Rint = 0.011
4160 measured reflections2 standard reflections every 120 reflections
3971 independent reflections intensity decay: 5.5%
3675 reflections with I > 0
Refinement top
R[F2 > 2σ(F2)] = 0.0660 restraints
wR(F2) = 0.050All H-atom parameters refined
S = 1.96Δρmax = 0.18 e Å3
3675 reflectionsΔρmin = 0.20 e Å3
203 parameters
Special details top

Refinement. The decay correction was applied.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Cl10.34437 (5)0.03290 (3)0.23420 (5)0.0639 (1)
Cl20.08634 (4)0.10110 (4)0.07649 (4)0.0637 (1)
Cl30.40776 (5)0.70156 (4)0.27110 (5)0.0756 (1)
Cl40.14139 (6)0.67599 (4)0.10548 (5)0.0799 (1)
O10.1030 (1)0.13495 (9)0.3672 (1)0.0619 (3)
O20.1424 (1)0.62212 (9)0.3894 (1)0.0613 (3)
C10.2876 (1)0.4723 (1)0.3453 (1)0.0384 (3)
C20.2057 (1)0.3747 (1)0.3647 (1)0.0403 (3)
C30.2715 (1)0.2716 (1)0.3358 (1)0.0369 (3)
C40.1841 (1)0.1701 (1)0.3198 (1)0.0420 (3)
C50.2227 (1)0.1378 (1)0.2013 (1)0.0424 (3)
C60.2866 (1)0.2521 (1)0.2013 (1)0.0393 (3)
C70.2116 (2)0.3273 (1)0.1027 (1)0.0516 (4)
C80.2200 (2)0.4342 (1)0.1089 (1)0.0522 (4)
C90.3068 (1)0.4963 (1)0.2141 (1)0.0399 (3)
C100.2661 (1)0.6155 (1)0.2264 (1)0.0463 (4)
C110.2183 (1)0.5820 (1)0.3394 (1)0.0428 (3)
C120.1891 (2)0.3731 (1)0.4957 (2)0.0693 (5)
H10.368 (1)0.472 (1)0.404 (1)0.045 (4)*
H20.121 (2)0.383 (1)0.314 (2)0.048 (4)*
H30.350 (2)0.258 (1)0.394 (1)0.050 (4)*
H40.381 (1)0.249 (1)0.193 (1)0.051 (4)*
H50.165 (2)0.297 (1)0.031 (2)0.060 (5)*
H60.178 (2)0.477 (1)0.043 (2)0.062 (5)*
H70.404 (2)0.489 (1)0.210 (1)0.049 (4)*
H80.147 (2)0.441 (2)0.511 (2)0.084 (6)*
H90.272 (2)0.374 (2)0.550 (2)0.098 (8)*
H100.145 (2)0.308 (2)0.504 (2)0.083 (6)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Cl0.0669 (2)0.0500 (2)0.0798 (3)0.0094 (2)0.0284 (2)0.0035 (2)
Cl20.0593 (2)0.0737 (2)0.0534 (2)0.0290 (2)0.0075 (2)0.0147 (2)
Cl30.0809 (2)0.0553 (2)0.1059 (3)0.0263 (2)0.0516 (2)0.0193 (2)
Cl40.0897 (3)0.0810 (3)0.0715 (3)0.0382 (2)0.0261 (2)0.0229 (2)
O10.0604 (6)0.0683 (7)0.0655 (6)0.0216 (5)0.0314 (5)0.0092 (5)
O20.0662 (6)0.0543 (6)0.0762 (7)0.0104 (5)0.0412 (5)0.0025 (5)
C10.0364 (6)0.0398 (6)0.0374 (6)0.0017 (5)0.0076 (5)0.0048 (5)
C20.0421 (7)0.0439 (7)0.0375 (6)0.0005 (5)0.0150 (5)0.0010 (5)
C30.0335 (6)0.0409 (6)0.0346 (6)0.0034 (5)0.0065 (5)0.0010 (5)
C40.0383 (6)0.0443 (7)0.0432 (7)0.0045 (5)0.0104 (5)0.0002 (6)
C50.0417 (6)0.0411 (6)0.0448 (7)0.0073 (5)0.0126 (5)0.0062 (6)
C60.0371 (6)0.0405 (6)0.0424 (7)0.0072 (5)0.0143 (5)0.0067 (5)
C70.0692 (9)0.0511 (8)0.0335 (7)0.0094 (7)0.0124 (6)0.0051 (6)
C80.0689 (9)0.0514 (8)0.0357 (7)0.0018 (7)0.0133 (6)0.0045 (6)
C90.0374 (6)0.0388 (6)0.0474 (7)0.0008 (5)0.0180 (5)0.0008 (5)
C100.0488 (7)0.0390 (7)0.0565 (8)0.0020 (6)0.0235 (6)0.0024 (6)
C110.0408 (7)0.0420 (7)0.0473 (7)0.0017 (6)0.0152 (5)0.0052 (6)
C120.110 (1)0.057 (1)0.0549 (8)0.001 (1)0.0461 (8)0.0010 (8)
Geometric parameters (Å, º) top
O1—C41.189 (2)C8—C91.487 (2)
O2—C111.189 (2)C9—C101.552 (2)
C1—C21.525 (2)C10—C111.538 (2)
C1—C91.566 (2)C1—H10.91 (5)
C1—C111.530 (2)C2—H20.91 (5)
C2—C31.523 (2)C6—H41.00 (4)
C2—C121.526 (2)C3—H30.91 (4)
C3—C41.530 (2)C7—H50.90 (5)
C3—C61.577 (2)C8—H60.91 (4)
C4—C51.541 (2)C9—H71.02 (5)
C5—C61.562 (2)C12—H80.99 (3)
C6—C71.492 (2)C12—H90.90 (5)
C7—C81.328 (2)C12—H100.95 (3)
C2—C1—C9120.1 (1)C2—C1—H1109 (1)
C2—C1—C11116.1 (1)C9—C1—H1111 (1)
C9—C1—C1188.2 (1)C11—C1—H1111 (1)
C1—C2—C3109.8 (1)C1—C2—H2107 (1)
C1—C2—C12111.1 (1)C3—C2—H2111 (1)
C3—C2—C12111.6 (1)C12—C2—H2105 (1)
C2—C3—C4115.6 (1)C2—C3—H3111 (1)
C2—C3—C6119.9 (1)C4—C3—H3109 (1)
C4—C3—C688.3 (1)C6—C3—H3111 (1)
O1—C4—C3135.5 (1)C3—C6—H4116 (1)
O1—C4—C5132.0 (1)C5—C6—H4113 (1)
C3—C4—C591.8 (1)C7—C6—H4106 (1)
C4—C5—C688.5 (1)C6—C7—H5116 (1)
C3—C6—C589.2 (1)C8—C7—H5118 (1)
C3—C6—C7116.6 (1)C7—C8—H6121 (1)
C5—C6—C7115.6 (1)C9—C8—H6113 (1)
C6—C7—C8124.8 (1)C1—C9—H7114 (1)
C7—C8—C9125.0 (1)C8—C9—H7108 (1)
C1—C9—C8116.4 (1)C10—C9—H7112 (1)
C1—C9—C1089.5 (1)C2—C12—H8108 (1)
C8—C9—C10116.3 (1)C2—C12—H9109 (1)
C9—C10—C1188.4 (1)C2—C12—H10107 (1)
O2—C11—C1135.4 (1)H8—C12—H9105 (1)
O2—C11—C10132.6 (1)H8—C12—H10117 (1)
C1—C11—C1091.4 (1)H9—C12—H10110 (1)
O1—C4—C3—C237.1 (2)C3—C4—C5—C611.2 (1)
O1—C4—C3—C6159.7 (2)C3—C6—C5—C410.9 (1)
O1—C4—C5—C6160.1 (2)C3—C6—C7—C853.6 (2)
O2—C11—C1—C235.9 (2)C4—C3—C2—C1270.9 (2)
O2—C11—C1—C9158.8 (2)C4—C3—C6—C510.9 (1)
O2—C11—C10—C9159.1 (2)C4—C3—C6—C7107.5 (1)
C1—C2—C3—C4165.5 (1)C4—C5—C6—C7108.5 (1)
C1—C2—C3—C661.7 (1)C5—C4—C3—C611.1 (1)
C1—C9—C8—C755.2 (2)C5—C6—C7—C8156.5 (2)
C1—C9—C10—C1112.0 (1)C6—C3—C2—C12174.7 (1)
C1—C11—C10—C912.3 (1)C6—C7—C8—C90.9 (3)
C2—C1—C9—C812.1 (2)C7—C8—C9—C10158.7 (2)
C2—C1—C9—C10131.4 (1)C8—C9—C1—C11107.2 (1)
C2—C1—C11—C10135.1 (1)C8—C9—C10—C11107.4 (1)
C2—C3—C4—C5133.7 (1)C9—C1—C2—C12174.6 (1)
C2—C3—C6—C5129.7 (1)C9—C1—C11—C1012.2 (1)
C2—C3—C6—C711.3 (2)C10—C9—C1—C1112.1 (1)
C3—C2—C1—C961.5 (1)C11—C1—C2—C1270.5 (2)
C3—C2—C1—C11165.6 (1)

Experimental details

Crystal data
Chemical formulaC12H10Cl4O2
Mr328.02
Crystal system, space groupMonoclinic, P21/a
Temperature (K)293
a, b, c (Å)10.320 (8), 12.390 (4), 11.219 (2)
β (°) 105.80 (4)
V3)1380 (1)
Z4
Radiation typeMo Kα
µ (mm1)0.85
Crystal size (mm)0.35 × 0.32 × 0.29
Data collection
DiffractometerEnraf-Nonius CAD-4
diffractometer
Absorption correction
No. of measured, independent and
observed (I > 0) reflections
4160, 3971, 3675
Rint0.011
(sin θ/λ)max1)0.703
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.066, 0.050, 1.96
No. of reflections3675
No. of parameters203
H-atom treatmentAll H-atom parameters refined
Δρmax, Δρmin (e Å3)0.18, 0.20

Computer programs: CAD-4 Software (Enraf-Nonius, 1989), CAD-4 Software, TEXSAN (Molecular Structure Corporation, 1992-1997), SIR92 (Altomare et al., 1993), TEXSAN.

 

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