Stereochemistry of two new polyfunctionalized gem-dihalo­cyclo­propanes

The two new gem-dihalogeno­cyclo­propanes (1'S,3R)-3-(2',2'-di­chloro-1'-methyl­cyclo­propyl)-6-oxoheptanoic acid, C₁₁H₁₆­Cl₂O₃, (2), and (1'S,3R)-3-(2',2'-di­bromo-1'-methyl­cyclo­propyl)-6-oxoheptanoic acid, C₁₁H₁₆Br₂O₃, (3), are isostructural. Both present two stereogenic centers at C1' and C3. The absolute configuration was determined by X-ray methods. The cyclo­propyl rings are unsymmetrical, the shortest bond being distal with respect to the alkyl-substituted C atom.

S1. Comment

Despite their high ring strain, cyclopropanes are commonly encountered among both naturally occurring and synthetic compounds. In addition, diastereoselectively substituted cyclopropanes have attracted attention as useful precursors of highly strained molecules (Boche et al., 1990; Tanabe et al., 1996) and biologically active pyrethroids (Hirota et al., 1996; Kunzer et al., 1996). Thus, promise of their usefulness as synthetic intermediates is growing rapidly. Here we describe the structure of two new polyfunctionalized dichloro and dibromo cyclopropanes 2 and 3, which could be valuable synthons for pyrethroid derivatives.

These two compounds were prepared from (R)-limonene oxide 1 by dihalocyclopropanation of the C7=C8 double bond followed by oxidation of oxirane ring under Sharpless conditions (see Experimental). In order to confirm the structure assignments and establish the absolute stereochemistry, single X-ray studies were carried out on both compounds. The two derivatives crystallize isotypically; only the chloro compound 2 is illustrated in Fig. 1 (a view of molecule 3 is given in the supplementary material). Identical numbering schemes have been employed in both molecules. The absolute configuration (1'S,3R) has been unambiguously determined by refinement of the Flack (1983) parameter. Examination of the cyclopropyl moieties indicates that the rings are unsymmetrical, with unequal C—C bond lengths (Tables 1 & 3). The C(3)—C(4) bond length in the chloro derivative is 1.479 (2) Å while the bonds adjacent to the methyl and the polyfonctional substituents are longer, C(2)—C(4) 1.504 (3) Å and C(2)—C(3) 1.525 (3) Å. The same trend persists in the bromo derivative with identical C—C distances within experimental error. The bond angles within the three-membered ring reflect the difference observed between bond lengths with the smallest angle at C(2), C(3)—C(2)—C(4) 58.42 (12)° (59.1 (4)° for 3). The Cambridge Structural Database (CSD; Allen & Kennard, 1993) has been searched for related dihalogenocyclopropane structures having CH₂ and CR₂ groups(scheme 2). The search was limited to independent alkyl substuents R₁ and R₂ and excludes structures with interconnected R₁ and R₂ for which additional strain might influence the distances within the ring. The geometry of these cyclopropane rings (Table 5) shows the same tendancy observed for 2 and 3 with a shortening of the distal bond opposite the alkyl-substituted carbon and a lengthening of the vicinal bonds linking the alkyl and H substituted carbon atoms with respect to the mean C—C(ring) length of 1.509 (2)%A (Allen, 1980). These results are in agreement with a previous report (Allen, 1980). The C—Cl bond lengths average 1.762 (2) Å and the C—Br 1.918 (6) Å and are in good agreement with related gem-dihalogenocyclopropanes, as are the X—C—X angles of 109.8 (1)° for 2 and 110.1 (3)° for 3.

The 3-oxobutyl chain has an extended configuration with torsion angles C1—C11—C12—C13 - 180.0 (2)° [-179.0 (6) for 3] and C11—C12—C13—C14 166.2 (2)° [166.3 (6) for 3](Table 1 and 3). The substituents at C1, the carboxyl group and the cyclopropane ring are anti with respect to the oxobutyl chain. The orientations of the carboxyl group and the cyclopropane ring are influenced by intramolecular contacts C—H^···O and C—H^···Cl (or Br) that could be classified as hydrogen bonds. An interaction between an H atom of the cyclopropane carbon C3 and the O1 of the carboxyl (Table 2 and 4) results in a twisted conformation of the carboxyl group C17/O1/O2 with respect to the C1/C16/C17 plane [dihedral angle 23.1 (2)° for 2 and 24.2° for 3]. A further interaction occurs between Cl1 and the H at C1 (Table 2 and 4).

Fig. 2 illustrates the packing of 2 (the packing of 3 is shown in a supplementary file) in the cell, with extracellular molecules included to show the single-strand hydrogen-bonded catemers. The chain proceeds from the carboxyl of one molecule to the remote ketone (O2) of a neighbour (Table 4). Among hydrogen bonding catemers, the observed prevalence of subtypes, describing the relation of adjacent molecules, is screw > translation > glide, with the chains often following a cell axis(Brunskill et al., 2001). Here, the components of the chain are related by a translation along b. It is noteworthy that there are also short halogen^···O1 contacts (3.056 (1) Å for the Cl and 3.020 (4) Å for the Br derivative) which connect the H bonded catemers.

S2. Experimental

(R)-limonene oxide 1 was treated, in phase transfer catalysis conditions, with dichloro (or dibromo) carbene (Tobey et al., 1964) generated in situ from the reaction of chloroform (or bromoform) with sodium hydroxide (Scheme 1). The resulting product was oxidized under Sharpless conditions (Carlson et al., 1981) leading to a diastereoisomeric mixture of 3-(2',2'-dihalo-1'-methylcyclopropyl)-6-oxo-heptanoic acid. Crystals of 2 and 3 were obtained from the corresponding mixture by fractional crystallization from chloroform.

S3. Refinement

The crystal of 3 was found to be twinned. However the two domains could be indexed and the two orientation matrices were used in the integration process (Stoe,1996) to produce a set of non-overlapped reflections for each domain. Only the data from the domain with the strongest intensities were retained. As the results were satisfactory, no search for untwinned crystal was undertaken.

In both compounds, all H atoms were introduced at calculated positions as riding atoms (C—H= 0.97–0.98 Å, OH= 0.82 Å), using AFIX 37 for CH₃ and AFIX 87 for hydroxyl groups, with a displacement parameter equal to 1.2 (CH, CH₂) or 1.5(CH₃,OH) times that of the parent atom. On the basis of 2006 and 1972 Friedel pairs for compounds 2 and 3 respectively, final refinement allowed the fraction contribution of the inverted enantiomer to vary (Bernardinelli & Flack, 1985; Flack, 1983), the absolute structure parameter quoted being the refined value of this contribution.

Computing details

For both compounds, data collection: IPDS Software (Stoe, 1996); cell refinement: IPDS Software (Stoe, 1996); data reduction: X-RED (Stoe, 1.08, 1996); program(s) used to solve structure: SIR97 (Altomare, et al.,1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 1998); molecular graphics: ORTEPIII( Burnett and Johnson,1996); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures

	Fig. 1. ORTEP view of molecule 2 (50% probability displacement ellipsoids)
	Fig. 2. Part of the structure of 2 showing the formation of the chain parallel to b axes. For the sake of clarity, H atoms not participating in the hydrogen bonding have been omitted. Symmetry codes: (i) x, y - 1,z; (ii) x, y + 1, z.

(2)

Crystal data

C11H16Cl2O3	F(000) = 560
Mr = 267.14	Dx = 1.414 Mg m^−3
Orthorhombic, P212121	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2ab	Cell parameters from 8000 reflections
a = 7.2419 (5) Å	θ = 2.3–26.0°
b = 9.7619 (8) Å	µ = 0.51 mm^−1
c = 17.7469 (16) Å	T = 180 K
V = 1254.61 (18) Å^3	Parallelepiped, colorless
Z = 4	0.42 × 0.40 × 0.13 mm

Data collection

Stoe IPDS diffractometer	2207 reflections with I > 2σ(I)
ϕ scans	Rint = 0.034
Absorption correction: multi-scan SORTAV, Blessing (1995)	θmax = 26.0°, θmin = 2.3°
Tmin = 0.788, Tmax = 0.913	h = −8→8
9901 measured reflections	k = −12→12
2418 independent reflections	l = −21→21

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.024	H-atom parameters constrained
wR(F^2) = 0.059	w = 1/[σ^2(Fo^2) + (0.0375P)^2 + 0.0454P] where P = (Fo^2 + 2Fc^2)/3
S = 1.04	(Δ/σ)max = 0.001
2418 reflections	Δρmax = 0.22 e Å^−3
148 parameters	Δρmin = −0.24 e Å^−3
0 restraints	Absolute structure: Flack H D (1983), Acta Cryst. A39, 876-881
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: 0.00 (5)

Special details

Experimental. The data were collected on a Stoe Imaging Plate Diffraction System (IPDS) equipped with an Oxford Cryosystems cooler device. The crystal-to-detector distance was 70 mm. 143 frames (3 min per frame) were obtained with 0 < ϕ < 200.2° and with the crystals rotated through 1.4° in ϕ.

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
Cl1	0.35355 (6)	0.88785 (5)	0.40672 (3)	0.03284 (12)
Cl2	0.29567 (7)	0.85649 (5)	0.24692 (3)	0.04162 (14)
O1	0.75687 (18)	0.50736 (11)	0.43588 (7)	0.0284 (3)
O2	1.02114 (19)	0.46852 (12)	0.37546 (8)	0.0309 (3)
H2	1.0003	0.3893	0.3883	0.046*
O3	0.9563 (2)	1.20229 (11)	0.39783 (7)	0.0312 (3)
C1	0.7519 (2)	0.78833 (14)	0.38088 (9)	0.0193 (3)
H1	0.6851	0.7735	0.4282	0.023*
C2	0.6208 (2)	0.75365 (15)	0.31616 (9)	0.0209 (3)
C3	0.4663 (3)	0.65102 (17)	0.33088 (9)	0.0253 (4)
H3A	0.4289	0.5920	0.2896	0.030*
H3B	0.4601	0.6092	0.3804	0.030*
C4	0.4233 (3)	0.79866 (17)	0.32490 (9)	0.0244 (4)
C11	0.8099 (2)	0.94040 (15)	0.37805 (9)	0.0205 (3)
H11A	0.9147	0.9503	0.3444	0.025*
H11B	0.7090	0.9943	0.3577	0.025*
C12	0.8612 (3)	0.99546 (16)	0.45525 (9)	0.0230 (3)
H12A	0.7561	0.9843	0.4886	0.028*
H12B	0.9614	0.9405	0.4753	0.028*
C13	0.9190 (2)	1.14322 (16)	0.45630 (9)	0.0215 (3)
C14	0.9290 (3)	1.21279 (17)	0.53099 (10)	0.0289 (4)
H14A	0.9508	1.3089	0.5237	0.043*
H14B	1.0281	1.1741	0.5600	0.043*
H14C	0.8146	1.2001	0.5574	0.043*
C16	0.9230 (3)	0.69706 (15)	0.38193 (10)	0.0250 (4)
H16A	0.9818	0.7018	0.3329	0.030*
H16B	1.0094	0.7336	0.4185	0.030*
C17	0.8874 (2)	0.54926 (15)	0.40043 (9)	0.0211 (3)
C21	0.7050 (3)	0.7567 (2)	0.23829 (10)	0.0353 (4)
H21A	0.8064	0.6934	0.2361	0.053*
H21B	0.7488	0.8474	0.2275	0.053*
H21C	0.6135	0.7312	0.2018	0.053*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cl1	0.0219 (2)	0.0366 (2)	0.0401 (2)	0.00046 (18)	0.00227 (18)	−0.01009 (19)
Cl2	0.0409 (3)	0.0428 (3)	0.0411 (3)	−0.0065 (2)	−0.0194 (2)	0.0139 (2)
O1	0.0276 (8)	0.0197 (5)	0.0379 (7)	−0.0034 (5)	0.0046 (5)	0.0052 (5)
O2	0.0324 (8)	0.0154 (5)	0.0450 (7)	0.0020 (5)	0.0078 (6)	0.0020 (5)
O3	0.0442 (8)	0.0163 (5)	0.0332 (7)	−0.0041 (5)	0.0025 (6)	0.0000 (5)
C1	0.0196 (9)	0.0158 (7)	0.0224 (7)	−0.0032 (6)	0.0010 (6)	0.0018 (6)
C2	0.0238 (10)	0.0154 (7)	0.0234 (8)	−0.0038 (6)	0.0006 (7)	−0.0003 (6)
C3	0.0281 (11)	0.0215 (8)	0.0262 (8)	−0.0074 (7)	−0.0027 (7)	0.0003 (7)
C4	0.0251 (10)	0.0238 (8)	0.0244 (8)	−0.0043 (7)	−0.0042 (7)	0.0009 (6)
C11	0.0211 (9)	0.0143 (6)	0.0259 (7)	−0.0018 (6)	−0.0008 (7)	0.0009 (6)
C12	0.0257 (10)	0.0172 (7)	0.0260 (8)	−0.0018 (7)	0.0005 (7)	0.0011 (6)
C13	0.0167 (9)	0.0188 (8)	0.0292 (8)	0.0034 (6)	−0.0009 (6)	−0.0007 (6)
C14	0.0299 (10)	0.0227 (8)	0.0341 (9)	0.0020 (7)	−0.0046 (8)	−0.0053 (7)
C16	0.0204 (9)	0.0157 (7)	0.0389 (9)	−0.0027 (7)	0.0021 (7)	0.0030 (7)
C17	0.0235 (10)	0.0151 (7)	0.0246 (8)	−0.0017 (6)	−0.0060 (7)	−0.0004 (6)
C21	0.0426 (12)	0.0364 (9)	0.0270 (9)	−0.0079 (8)	0.0089 (9)	−0.0041 (7)

Geometric parameters (Å, º)

Cl1—C4	1.7668 (17)	C11—C12	1.518 (2)
Cl2—C4	1.7572 (17)	C11—H11A	0.9700
O1—C17	1.207 (2)	C11—H11B	0.9700
O2—C17	1.325 (2)	C12—C13	1.502 (2)
O2—H2	0.8200	C12—H12A	0.9700
O3—C13	1.2175 (19)	C12—H12B	0.9700
C1—C16	1.526 (2)	C13—C14	1.491 (2)
C1—C2	1.528 (2)	C14—H14A	0.9600
C1—C11	1.5436 (19)	C14—H14B	0.9600
C1—H1	0.9800	C14—H14C	0.9600
C2—C4	1.505 (3)	C16—C17	1.502 (2)
C2—C21	1.511 (2)	C16—H16A	0.9700
C2—C3	1.524 (2)	C16—H16B	0.9700
C3—C4	1.478 (2)	C21—H21A	0.9600
C3—H3A	0.9700	C21—H21B	0.9600
C3—H3B	0.9700	C21—H21C	0.9600
C17—O2—H2	109.5	C13—C12—C11	114.80 (13)
C16—C1—C2	112.60 (13)	C13—C12—H12A	108.6
C16—C1—C11	109.92 (13)	C11—C12—H12A	108.6
C2—C1—C11	110.96 (13)	C13—C12—H12B	108.6
C16—C1—H1	107.7	C11—C12—H12B	108.6
C2—C1—H1	107.7	H12A—C12—H12B	107.5
C11—C1—H1	107.7	O3—C13—C14	122.08 (14)
C4—C2—C21	118.20 (15)	O3—C13—C12	120.41 (13)
C4—C2—C3	58.42 (11)	C14—C13—C12	117.51 (14)
C21—C2—C3	117.78 (14)	C13—C14—H14A	109.5
C4—C2—C1	116.65 (14)	C13—C14—H14B	109.5
C21—C2—C1	115.61 (16)	H14A—C14—H14B	109.5
C3—C2—C1	118.21 (13)	C13—C14—H14C	109.5
C4—C3—C2	60.11 (12)	H14A—C14—H14C	109.5
C4—C3—H3A	117.8	H14B—C14—H14C	109.5
C2—C3—H3A	117.8	C17—C16—C1	115.08 (15)
C4—C3—H3B	117.8	C17—C16—H16A	108.5
C2—C3—H3B	117.8	C1—C16—H16A	108.5
H3A—C3—H3B	114.9	C17—C16—H16B	108.5
C3—C4—C2	61.46 (11)	C1—C16—H16B	108.5
C3—C4—Cl2	118.73 (12)	H16A—C16—H16B	107.5
C2—C4—Cl2	120.84 (13)	O1—C17—O2	123.05 (14)
C3—C4—Cl1	118.80 (12)	O1—C17—C16	125.03 (15)
C2—C4—Cl1	120.02 (12)	O2—C17—C16	111.88 (15)
Cl2—C4—Cl1	109.80 (10)	C2—C21—H21A	109.5
C12—C11—C1	112.20 (13)	C2—C21—H21B	109.5
C12—C11—H11A	109.2	H21A—C21—H21B	109.5
C1—C11—H11A	109.2	C2—C21—H21C	109.5
C12—C11—H11B	109.2	H21A—C21—H21C	109.5
C1—C11—H11B	109.2	H21B—C21—H21C	109.5
H11A—C11—H11B	107.9
C16—C1—C2—C4	158.71 (14)	C1—C2—C4—Cl2	143.58 (12)
C11—C1—C2—C4	−77.61 (17)	C21—C2—C4—Cl1	−144.47 (14)
C16—C1—C2—C21	−55.52 (18)	C3—C2—C4—Cl1	108.60 (15)
C11—C1—C2—C21	68.17 (19)	C1—C2—C4—Cl1	0.4 (2)
C16—C1—C2—C3	92.01 (17)	C16—C1—C11—C12	−81.29 (17)
C11—C1—C2—C3	−144.30 (14)	C2—C1—C11—C12	153.51 (15)
C21—C2—C3—C4	−107.65 (17)	C1—C11—C12—C13	−179.97 (15)
C1—C2—C3—C4	105.53 (16)	C11—C12—C13—O3	−14.1 (2)
C2—C3—C4—Cl2	111.55 (16)	C11—C12—C13—C14	166.17 (16)
C2—C3—C4—Cl1	−110.55 (15)	C2—C1—C16—C17	−67.65 (18)
C21—C2—C4—C3	106.93 (16)	C11—C1—C16—C17	168.09 (14)
C1—C2—C4—C3	−108.20 (15)	C1—C16—C17—O1	−24.4 (2)
C21—C2—C4—Cl2	−1.3 (2)	C1—C16—C17—O2	157.88 (14)
C3—C2—C4—Cl2	−108.21 (15)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O2—H2···O3^i	0.82	1.86	2.671 (2)	169
C3—H3B···O1	0.98	2.56	3.141 (2)	118
C1—H1···Cl1	0.98	2.67	3.078 (2)	105

Symmetry code: (i) x, y−1, z.

(3)

Crystal data

C11H16Br2O3	F(000) = 704
Mr = 356.06	Dx = 1.819 Mg m^−3
Orthorhombic, P212121	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2ab	Cell parameters from 8000 reflections
a = 7.4006 (5) Å	θ = 2.3–26.0°
b = 9.7511 (10) Å	µ = 6.23 mm^−1
c = 18.0171 (13) Å	T = 180 K
V = 1300.19 (19) Å^3	Parallelepiped, colorless
Z = 4	0.3 × 0.28 × 0.18 mm

Data collection

Stoe IPDS diffractometer	2070 reflections with I > 2σ(I)
ϕ scans	Rint = 0.074
Absorption correction: multi-scan SORTAV, Blessing (1995)	θmax = 26.1°, θmin = 2.3°
Tmin = 0.162, Tmax = 0.348	h = −8→8
9311 measured reflections	k = −11→11
2376 independent reflections	l = −22→22

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.037	H-atom parameters constrained
wR(F^2) = 0.096	w = 1/[σ^2(Fo^2) + (0.0553P)^2 + 0.1506P] where P = (Fo^2 + 2Fc^2)/3
S = 1.09	(Δ/σ)max = 0.016
2376 reflections	Δρmax = 0.51 e Å^−3
148 parameters	Δρmin = −0.56 e Å^−3
0 restraints	Absolute structure: Flack H D (1983), Acta Cryst. A39, 876-881
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: −0.03 (2)

Special details

Experimental. The data were collected on a Stoe Imaging Plate Diffraction System (IPDS) equipped with an Oxford Cryosystems cooler device. The crystal-to-detector distance was 70 mm. 143 frames (4 min per frame) were obtained with 0 < ϕ < 200.2° and with the crystals rotated through 1.4° in ϕ.

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
Br1	0.35714 (9)	0.88593 (6)	0.41179 (3)	0.03788 (17)
Br2	0.29276 (10)	0.83970 (7)	0.24107 (3)	0.0465 (2)
O1	0.7668 (6)	0.4995 (4)	0.4370 (2)	0.0347 (10)
O2	1.0233 (7)	0.4611 (4)	0.3769 (3)	0.0399 (10)
H2	1.0029	0.3818	0.3896	0.060*
O3	0.9632 (7)	1.1939 (4)	0.4001 (2)	0.0405 (11)
C1	0.7587 (8)	0.7810 (5)	0.3802 (3)	0.0270 (12)
H1	0.6928	0.7664	0.4267	0.032*
C2	0.6291 (9)	0.7452 (5)	0.3164 (3)	0.0263 (11)
C3	0.4830 (8)	0.6403 (5)	0.3326 (3)	0.0304 (12)
H3A	0.4473	0.5792	0.2927	0.036*
H3B	0.4799	0.6000	0.3818	0.036*
C4	0.4359 (9)	0.7880 (6)	0.3254 (3)	0.0339 (13)
C11	0.8158 (8)	0.9331 (5)	0.3781 (3)	0.0282 (13)
H11A	0.9206	0.9429	0.3463	0.034*
H11B	0.7185	0.9871	0.3569	0.034*
C12	0.8607 (10)	0.9880 (5)	0.4550 (3)	0.0336 (13)
H12A	0.7547	0.9781	0.4862	0.040*
H12B	0.9555	0.9315	0.4761	0.040*
C13	0.9207 (8)	1.1353 (5)	0.4574 (3)	0.0316 (13)
C14	0.9257 (10)	1.2040 (6)	0.5312 (3)	0.0388 (15)
H14A	0.9340	1.3014	0.5245	0.058*
H14B	1.0289	1.1722	0.5586	0.058*
H14C	0.8175	1.1825	0.5582	0.058*
C16	0.9263 (9)	0.6900 (5)	0.3825 (3)	0.0321 (13)
H16A	0.9850	0.6942	0.3344	0.039*
H16B	1.0096	0.7276	0.4187	0.039*
C17	0.8928 (8)	0.5417 (5)	0.4014 (3)	0.0293 (13)
C21	0.7122 (10)	0.7487 (6)	0.2392 (3)	0.0428 (15)
H21A	0.8116	0.6856	0.2370	0.064*
H21B	0.7547	0.8397	0.2288	0.064*
H21C	0.6227	0.7231	0.2032	0.064*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Br1	0.0343 (3)	0.0354 (3)	0.0439 (3)	0.0003 (2)	0.0014 (3)	−0.0071 (2)
Br2	0.0482 (4)	0.0462 (4)	0.0450 (4)	−0.0071 (3)	−0.0144 (3)	0.0133 (3)
O1	0.038 (3)	0.0238 (19)	0.042 (2)	−0.0044 (17)	0.0003 (18)	0.0040 (15)
O2	0.041 (3)	0.0186 (19)	0.061 (3)	0.0012 (18)	0.008 (2)	0.0009 (17)
O3	0.061 (3)	0.021 (2)	0.039 (2)	−0.0048 (18)	0.004 (2)	0.0004 (15)
C1	0.031 (4)	0.016 (2)	0.034 (3)	−0.002 (2)	0.000 (2)	0.0023 (18)
C2	0.033 (3)	0.018 (2)	0.028 (3)	0.000 (2)	0.001 (2)	0.0009 (17)
C3	0.035 (4)	0.021 (3)	0.035 (3)	−0.007 (2)	−0.002 (2)	0.000 (2)
C4	0.040 (4)	0.025 (3)	0.036 (3)	−0.008 (2)	−0.003 (2)	−0.002 (2)
C11	0.032 (4)	0.018 (2)	0.035 (3)	−0.003 (2)	−0.002 (2)	0.0010 (18)
C12	0.041 (4)	0.024 (3)	0.035 (3)	0.001 (3)	0.000 (3)	0.001 (2)
C13	0.033 (4)	0.024 (3)	0.038 (3)	0.002 (2)	0.001 (2)	0.000 (2)
C14	0.040 (4)	0.033 (3)	0.043 (3)	0.002 (3)	−0.005 (3)	−0.008 (2)
C16	0.038 (4)	0.019 (3)	0.040 (3)	0.000 (2)	0.003 (2)	0.001 (2)
C17	0.033 (4)	0.020 (3)	0.035 (3)	−0.001 (2)	−0.005 (2)	0.001 (2)
C21	0.054 (4)	0.041 (3)	0.033 (3)	0.001 (3)	0.008 (3)	0.002 (2)

Geometric parameters (Å, º)

Br1—C4	1.917 (6)	C11—C12	1.521 (7)
Br2—C4	1.919 (6)	C11—H11A	0.9700
O1—C17	1.204 (7)	C11—H11B	0.9700
O2—C17	1.321 (7)	C12—C13	1.504 (8)
O2—H2	0.8200	C12—H12A	0.9700
O3—C13	1.220 (7)	C12—H12B	0.9700
C1—C16	1.525 (8)	C13—C14	1.490 (8)
C1—C2	1.537 (8)	C14—H14A	0.9600
C1—C11	1.543 (7)	C14—H14B	0.9600
C1—H1	0.9800	C14—H14C	0.9600
C2—C4	1.499 (9)	C16—C17	1.506 (7)
C2—C3	1.517 (8)	C16—H16A	0.9700
C2—C21	1.520 (8)	C16—H16B	0.9700
C3—C4	1.488 (8)	C21—H21A	0.9600
C3—H3A	0.9700	C21—H21B	0.9600
C3—H3B	0.9700	C21—H21C	0.9600
C17—O2—H2	109.5	C13—C12—C11	115.3 (4)
C16—C1—C2	113.3 (4)	C13—C12—H12A	108.5
C16—C1—C11	109.7 (5)	C11—C12—H12A	108.5
C2—C1—C11	111.8 (4)	C13—C12—H12B	108.5
C16—C1—H1	107.3	C11—C12—H12B	108.5
C2—C1—H1	107.3	H12A—C12—H12B	107.5
C11—C1—H1	107.3	O3—C13—C14	122.6 (5)
C4—C2—C3	59.1 (4)	O3—C13—C12	119.9 (5)
C4—C2—C21	118.6 (5)	C14—C13—C12	117.5 (5)
C3—C2—C21	118.7 (5)	C13—C14—H14A	109.5
C4—C2—C1	116.8 (5)	C13—C14—H14B	109.5
C3—C2—C1	117.0 (4)	H14A—C14—H14B	109.5
C21—C2—C1	115.3 (6)	C13—C14—H14C	109.5
C4—C3—C2	59.9 (4)	H14A—C14—H14C	109.5
C4—C3—H3A	117.8	H14B—C14—H14C	109.5
C2—C3—H3A	117.8	C17—C16—C1	115.5 (5)
C4—C3—H3B	117.8	C17—C16—H16A	108.4
C2—C3—H3B	117.8	C1—C16—H16A	108.4
H3A—C3—H3B	114.9	C17—C16—H16B	108.4
C3—C4—C2	61.0 (4)	C1—C16—H16B	108.4
C3—C4—Br1	118.9 (4)	H16A—C16—H16B	107.5
C2—C4—Br1	121.1 (4)	O1—C17—O2	122.7 (5)
C3—C4—Br2	116.9 (4)	O1—C17—C16	125.1 (5)
C2—C4—Br2	121.0 (4)	O2—C17—C16	112.1 (5)
Br1—C4—Br2	110.1 (3)	C2—C21—H21A	109.5
C12—C11—C1	112.1 (4)	C2—C21—H21B	109.5
C12—C11—H11A	109.2	H21A—C21—H21B	109.5
C1—C11—H11A	109.2	C2—C21—H21C	109.5
C12—C11—H11B	109.2	H21A—C21—H21C	109.5
C1—C11—H11B	109.2	H21B—C21—H21C	109.5
H11A—C11—H11B	107.9
C16—C1—C2—C4	157.4 (5)	C1—C2—C4—Br1	1.2 (6)
C11—C1—C2—C4	−78.1 (6)	C3—C2—C4—Br2	−105.8 (5)
C16—C1—C2—C3	90.2 (6)	C21—C2—C4—Br2	2.3 (7)
C11—C1—C2—C3	−145.2 (5)	C1—C2—C4—Br2	147.4 (4)
C16—C1—C2—C21	−56.4 (6)	C16—C1—C11—C12	−81.8 (6)
C11—C1—C2—C21	68.1 (6)	C2—C1—C11—C12	151.7 (5)
C21—C2—C3—C4	−108.0 (6)	C1—C11—C12—C13	179.0 (6)
C1—C2—C3—C4	106.6 (5)	C11—C12—C13—O3	−13.8 (9)
C2—C3—C4—Br1	−111.7 (5)	C11—C12—C13—C14	166.3 (6)
C2—C3—C4—Br2	112.2 (5)	C2—C1—C16—C17	−67.1 (6)
C21—C2—C4—C3	108.1 (5)	C11—C1—C16—C17	167.2 (4)
C1—C2—C4—C3	−106.9 (5)	C1—C16—C17—O1	−25.8 (8)
C3—C2—C4—Br1	108.1 (5)	C1—C16—C17—O2	157.0 (5)
C21—C2—C4—Br1	−143.8 (5)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O2—H2···O3^i	0.82	1.87	2.676 (5)	170
C3—H3B···O1	0.97	2.54	3.136 (7)	120
C1—H1···Br1	0.98	2.76	3.194 (6)	108

Symmetry code: (i) x, y−1, z.