rac-(Z)-Ethyl 2-bromo-2-[(3R,5R)-3-bromo-5-methyl­tetra­hydro­furan-2-yl­idene]acetate

In the title compound, C₉H₁₂Br₂O₃, a (tetra­hydro­furan-2-yl­idene)acetate, the double bond has the Z form. In the tetra­hydro­furan group, the relative configuration of the Br atom in the 3-position and the methyl group in the 5-position is anti. The compound crystallizes with two independent mol­ecules per asymmetric unit and, in the crystal structure, the individual mol­ecules are linked to their symmetry-equivalent mol­ecules by C—H...O hydrogen bonds, so forming centrosymmetric hydrogen-bonded dimers.

S1. Comment

For the synthesis of bioactive molecules reduced derivatives of substituted furans have been intensively studied as synthetic building blocks. α-(Tetrahydrofuran-2-ylidene)acetates have been synthesized using widely different strategies (Bryson, 1973). They are the most common intermediates in many of the reported syntheses of nonactic acid (Ferraz & Payret-Arrua, 1998), which is the degradation product of the ionophore nonactin (Keller-Schierlein or Keller-Schlierlein & Gerlach, 1968). Nonactin, the lowest homologue of the nactin family, is used in analytical chemistry as an ammonia sensor (Bühlmann et al., 1998) and has shown antibiotic and insecticidal properties (Meyers et al., 1965; Oishi et al., 1970). In the context of our research programme on the preparation of more hydrophobic nonactin derivatives (Loiseau, 2006), we decided to study the functionalization of models of nonactic acid, for example, compound (III). Hydrophobic nonactin derivatives should have a longer life-time in the semi-permeable membrane of ammonia sensors (Pretsch et al., 1988). The life span of these electrodes is limited owing to the loss of nonactin into the aqueous solution. The synthetic strategy to prepare racemic (III) involves two steps. Firstly, compound (II) was synthesized by the radical coupling (Baciocchi et al., 1992) of 2-methylfuran, (I), with ethyl iodoacetate. The furan ring was then hydrogenated (Schmidt & Werner, 1986) to give racemic (III) [see scheme].

One of our approaches to modify compound (III) was based on the introduction of a Br atom as a functional group. Bromine can be replaced using well known reactions, such as radical or nucleophilic substitution reactions, Grignard reactions or Reformatsky enolate chemistry. We needed to develop a method to introduce selectively the Br atom in the α-position of the ester function. On bromination (Schultz et al., 1983) of (III), however, the unexpected polybrominated racemic compound (IV) was isolated. We report here on the structure of this totally new highly functionalized (tetrahydrofuran-2-ylidene)acetate.

The molecular structure of the two independent molecules (A and B) of (IV) are illustrated in Fig. 1. Selected bond distances and angles for molecule A are given in Table 1, and non-bonded intermolecular Br···O and Br···Br contacts are listed in Table 2. It can be seen that the relative configuration of the Br atom in the 3-position (C2) and of the methyl group in the 5-position (C4) of the tetrahydrofuran (THF) group is anti. The THF ring in each molecule has an envelope conformation, with atom C3 as the flap atom in molecule A and atom C13 in molecule B. The Cremer & Pople (1975) puckering parameters are Q(2) = 0.318 (4) Å and ϕ(2) = 106.6 (7)° for molecule A, and Q(2) = 0.339 (4) Å and ϕ(2) = 107.4 (7)° for molecule B. The two molecules differ only in the orientation of the ethyl acetate group with respect to the plane through the bromoylidene moiety. The relevant torsion angles about the C5—C6 (molecule A) and C15—C16 bonds (molecule B) are given in Table 1, and it can be seen that the difference is of the order of ca 4°.

In the crystal structure of (IV) the individual molecules (A and B) are linked to their symmtery-equivalent molecules by C—H···O hydrogen bonds, so forming centrosymmetric hydrogen-bonded dimers (details are given in Table 3). There are also two short Br···Br contacts (Table 2) of 3.5681 (7) and 3.6126 (7) Å. A search of of the Cambridge Structural Database (CSD; Version 1.8, last update May 2006; Allen, 2002), indicates that such short intermolecular Br···Br distances are not unusual. These centrosymmetric dimers are further linked by a Br···O interaction of distance 3.220 (3) Å (see Table 2 and Fig. 2 for details). This interaction is also associated with the C13—H13A···O5^iv interaction, leading to a Br···O···H13A angle of ca 139°. A search of the CSD indicates that O···Br interactions involving carbonyl O atoms are not uncommon; more than 600 such interactions in the range 2.80–3.37 Å have been observed previously.

The two Br atoms introduced are vinylic [the average bond distance is 1.894 (2) Å] and allylic [the average bond distance is 1.974 (2) Å]. Effectively, only arylic, vinylic and allylic halogen atoms can prevent α-elimination and can therefore be involved in modern palladium-catalyzed organometallic couplings such as the Heck or Suzuki reactions. It is highly probable that (IV) was the synthetic result of three radical eliminations followed by an elimination of HBr. The X-ray diffraction analysis of (IV) has proven the possible synthetic mechanism of formation, where the Br atom in the 3-position of the THF ring is inserted on the less hindered face, i.e. anti with respect to the methyl group in the 5-position of the THF ring.

A search of the CSD reveals only three structures containing the tetraydrofuran-2-ylidene acetate moiety (Brussani et al., 1986; Scheffler et al., 2002; Bellur et al., 2005), none of which are substitued in the α-position of the ester function. To the best of our knowledge this is also the first crystal structure analysis of a tetrahydrofuran-2-ylidene compound in which a halogen substituent is present on the THF ring.

S2. Experimental

Compound (II), ethyl 2-(5-methylfuran-2-yl)acetate, was prepared by stirring freshly distilled 2-methylfuran (100 g, 1218 mmol), ethyl iodoacetate (7.66 ml, 64.1 mmol) and FeSO₄·7H₂O (8.20 g, 29.5 mmol) in dimethylsulfoxide (550 ml) in a three-necked 1 l flask. H₂O₂, 35% in water-brine (10.4 ml, 121.8 mmol), was then added dropwise at 288–303 K and the temperature was maintained with a water bath. After 5 h, 550 ml of brine were added portionwise. The product obtained was extracted four times with 200 ml of diethyl ether. The combined organic layers were washed with 500 ml of brine, and then dried over MgSO₄. Filtration and evaporation in vacuo afforded 12.7 g of a brown oil. This resulting oil was purified by chromatography on a silica gel column using n-hexane/AcOEt (95:5) to afford the desired product, (II), as a yellow oil (6.40 g, 38 mmol, yield 60%).

Compound (III), racemic ethyl 2-(5-methyl-tetrahydrofuran-2-yl)acetate, was prepared by placing compound (II) (400 mg, 2.38 mmol) and 5% rhodium over alumina (50 mg, 0.024 mmol) in 15 ml of MeOH, under 3.8 atm pressure of hydrogen in a Parr apparatus. After 16 h, the mixture was filtered on a celite/silica 2/1 mixture. Evaporation in vacuo afforded compound (III) (316 mg, 1.83 mmol, 77%). According to NMR and GC analyses, the cis/trans ratio was 85:15.

Compound (IV) was prepared by magnetically stirring compound (III) (0.5 g, 2.9 mmol) in 15 ml of dried benzene in a three-necked 25 ml flask fitted with a reflux condenser and under an atmosphere of argon. N-Bromo succinimide (1.86 g, 10.5 mmol) was added slowly and the mixture was refluxed for 2 h under the illumination of a 200 Watt lamp. The mixture was cooled to 283 K, and the solid obtained was filtered off. Benzene was removed by evaporation in vacuo. The oil obtained was purified by chromatography on a silica gel column using as eluant n-hexane/AcOEt (9:1), giving finally the brominated product (IV), as a yellow oil (250 mg, 0.7 mmol, yield 26%). As it contained a small amount of impurities, ca 100 mg were recrystallized in hexane. Colourless crystals, suitable for X-ray diffraction, were obtained.

S3. Refinement

The H atoms could all be located from difference Fourier maps. They were included in calculated positons and treated as riding atoms, with C—H distances of 0.98–1.00 Å and with U_iso(H) values of 1.2 or 1.5 times U_eq(parent C atom).

Computing details

Data collection: X-AREA (Stoe & Cie, 2005); cell refinement: X-AREA; data reduction: X-RED32 (Stoe & Cie, 2005); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 2003); software used to prepare material for publication: SHELXL97.

Figures

	Fig. 1. Molecular structure of the two independent molecules (A above and B below) of the racemic compound (IV), showing the crystallographic atom-numbering scheme and displacement ellipsoids drawn at the 50% probability level.
	Fig. 2. A segment of the crystal packing of compound (IV) viewed down the a axis. The Br···O interactions and the C—H···O hydrogen bonds are shown as dashed lines [symmetry codes: (i) −x, −y + 1, −z + 1; (iv) −x, −y + 2, −z].

rac-(Z)-Ethyl 2-bromo-2-[(3R,5R)-3-bromo-5-methyltetrahydrofuran-2-ylidene]acetate

Crystal data

C9H12Br2O3	Z = 4
Mr = 328.01	F(000) = 640
Triclinic, P1	Dx = 1.909 Mg m^−3
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 9.0779 (8) Å	Cell parameters from 12061 reflections
b = 9.1402 (9) Å	θ = 2.5–29.6°
c = 15.3942 (13) Å	µ = 7.09 mm^−1
α = 85.740 (7)°	T = 173 K
β = 82.209 (7)°	Block, colourless
γ = 64.386 (7)°	0.30 × 0.23 × 0.20 mm
V = 1140.98 (18) Å^3

Data collection

Stoe IPDS-2 diffractometer	6151 independent reflections
Radiation source: fine-focus sealed tube	4464 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.060
ϕ and ω scans	θmax = 29.2°, θmin = 2.5°
Absorption correction: multi-scan (MULABS in PLATON; Spek, 2003)	h = −12→12
Tmin = 0.126, Tmax = 0.245	k = −10→12
17073 measured reflections	l = −21→20

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.040	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.088	H-atom parameters constrained
S = 0.90	w = 1/[σ^2(Fo^2) + (0.0485P)^2] where P = (Fo^2 + 2Fc^2)/3
6151 reflections	(Δ/σ)max = 0.001
257 parameters	Δρmax = 0.83 e Å^−3
0 restraints	Δρmin = −1.19 e Å^−3

Special details

Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles

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 (Ų)

	x	y	z	Uiso*/Ueq
Br1	0.28156 (5)	0.23000 (5)	0.73539 (3)	0.0299 (1)
Br2	0.05419 (4)	0.18564 (5)	0.44957 (3)	0.0269 (1)
O1	0.3496 (3)	0.1916 (3)	0.50676 (18)	0.0227 (7)
O2	−0.2264 (3)	0.4135 (4)	0.5739 (2)	0.0309 (9)
O3	−0.0801 (3)	0.4688 (3)	0.66288 (19)	0.0269 (8)
C1	0.2143 (4)	0.2854 (4)	0.5589 (2)	0.0169 (9)
C2	0.2591 (4)	0.3640 (4)	0.6271 (2)	0.0195 (9)
C3	0.4266 (4)	0.3519 (4)	0.5861 (3)	0.0219 (10)
C4	0.4966 (4)	0.1979 (4)	0.5326 (3)	0.0220 (10)
C5	0.0644 (4)	0.3013 (4)	0.5441 (2)	0.0185 (9)
C6	−0.0953 (4)	0.3985 (4)	0.5939 (3)	0.0217 (10)
C7	−0.2331 (5)	0.5707 (6)	0.7147 (3)	0.0351 (13)
C8	−0.1875 (6)	0.6410 (7)	0.7856 (3)	0.0448 (16)
C9	0.6076 (5)	0.1984 (5)	0.4504 (3)	0.0292 (11)
Br3	0.16092 (5)	0.90195 (6)	0.27870 (3)	0.0342 (1)
Br4	0.01313 (4)	0.68854 (5)	0.01336 (3)	0.0246 (1)
O4	0.2958 (3)	0.7220 (3)	0.07359 (19)	0.0253 (8)
O5	−0.2827 (3)	0.9825 (3)	0.08799 (19)	0.0285 (8)
O6	−0.1551 (3)	1.0954 (3)	0.1561 (2)	0.0277 (8)
C11	0.1524 (4)	0.8454 (4)	0.1021 (2)	0.0180 (9)
C12	0.1831 (4)	0.9613 (4)	0.1533 (2)	0.0207 (10)
C13	0.3614 (4)	0.9230 (5)	0.1206 (3)	0.0242 (10)
C14	0.4353 (4)	0.7430 (5)	0.1021 (3)	0.0258 (10)
C15	0.0086 (4)	0.8549 (4)	0.0812 (2)	0.0189 (9)
C16	−0.1579 (4)	0.9817 (4)	0.1077 (2)	0.0202 (9)
C17	−0.3124 (5)	1.2252 (5)	0.1853 (3)	0.0331 (13)
C18	−0.2763 (5)	1.3422 (5)	0.2326 (3)	0.0379 (14)
C19	0.5757 (5)	0.6861 (6)	0.0289 (4)	0.0415 (15)
H2A	0.17720	0.47900	0.63720	0.0230*
H3A	0.41490	0.44770	0.54810	0.0260*
H3B	0.49730	0.34250	0.63180	0.0260*
H4A	0.55510	0.10130	0.57020	0.0270*
H7A	−0.29170	0.50530	0.74030	0.0420*
H7B	−0.30560	0.65820	0.67750	0.0420*
H8A	−0.13300	0.70840	0.75930	0.0670*
H8B	−0.11270	0.55310	0.82060	0.0670*
H8C	−0.28700	0.70780	0.82340	0.0670*
H9A	0.54870	0.29230	0.41330	0.0440*
H9B	0.64060	0.09840	0.41820	0.0440*
H9C	0.70560	0.20490	0.46610	0.0440*
H12A	0.10770	1.07690	0.14130	0.0250*
H13A	0.36970	0.98650	0.06670	0.0290*
H13B	0.41630	0.94550	0.16580	0.0290*
H14A	0.47000	0.67810	0.15690	0.0310*
H17A	−0.38010	1.18220	0.22520	0.0400*
H17B	−0.37280	1.27980	0.13470	0.0400*
H18A	−0.21020	1.38450	0.19220	0.0570*
H18B	−0.21530	1.28610	0.28210	0.0570*
H18C	−0.37990	1.43230	0.25440	0.0570*
H19A	0.66620	0.70680	0.04420	0.0620*
H19B	0.53790	0.74520	−0.02550	0.0620*
H19C	0.61390	0.56960	0.02060	0.0620*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Br1	0.0296 (2)	0.0417 (2)	0.0234 (2)	−0.0196 (2)	−0.0084 (2)	0.0072 (2)
Br2	0.0267 (2)	0.0326 (2)	0.0292 (2)	−0.0180 (2)	−0.0078 (1)	−0.0043 (2)
O1	0.0162 (11)	0.0262 (13)	0.0289 (14)	−0.0118 (10)	0.0008 (10)	−0.0088 (11)
O2	0.0185 (12)	0.0424 (16)	0.0363 (17)	−0.0161 (12)	−0.0091 (11)	0.0032 (13)
O3	0.0163 (11)	0.0308 (14)	0.0320 (16)	−0.0081 (10)	0.0008 (10)	−0.0100 (12)
C1	0.0179 (14)	0.0165 (15)	0.0184 (17)	−0.0092 (12)	−0.0024 (12)	−0.0010 (13)
C2	0.0171 (14)	0.0237 (17)	0.0208 (18)	−0.0115 (13)	−0.0018 (13)	−0.0016 (14)
C3	0.0165 (14)	0.0261 (18)	0.0273 (19)	−0.0124 (14)	−0.0049 (13)	−0.0002 (15)
C4	0.0146 (14)	0.0231 (17)	0.031 (2)	−0.0101 (13)	−0.0048 (14)	0.0001 (15)
C5	0.0184 (15)	0.0213 (16)	0.0196 (17)	−0.0113 (13)	−0.0054 (13)	0.0011 (13)
C6	0.0201 (15)	0.0225 (17)	0.027 (2)	−0.0139 (14)	−0.0037 (14)	0.0049 (15)
C7	0.0181 (16)	0.041 (2)	0.043 (3)	−0.0104 (16)	0.0048 (16)	−0.012 (2)
C8	0.043 (2)	0.051 (3)	0.033 (3)	−0.015 (2)	0.008 (2)	−0.012 (2)
C9	0.0218 (17)	0.033 (2)	0.035 (2)	−0.0147 (16)	0.0031 (15)	−0.0057 (17)
Br3	0.0445 (2)	0.0425 (2)	0.0204 (2)	−0.0225 (2)	−0.0053 (2)	−0.0013 (2)
Br4	0.0222 (2)	0.0262 (2)	0.0299 (2)	−0.0136 (1)	−0.0019 (1)	−0.0085 (2)
O4	0.0165 (11)	0.0228 (12)	0.0368 (16)	−0.0069 (10)	−0.0034 (10)	−0.0112 (11)
O5	0.0187 (12)	0.0339 (15)	0.0325 (16)	−0.0090 (11)	−0.0075 (11)	−0.0045 (12)
O6	0.0181 (11)	0.0263 (13)	0.0383 (17)	−0.0081 (10)	−0.0001 (11)	−0.0133 (12)
C11	0.0170 (14)	0.0193 (15)	0.0203 (17)	−0.0094 (12)	−0.0038 (12)	−0.0018 (13)
C12	0.0202 (15)	0.0248 (17)	0.0206 (18)	−0.0119 (14)	−0.0061 (13)	−0.0001 (14)
C13	0.0207 (16)	0.0278 (18)	0.030 (2)	−0.0145 (14)	−0.0073 (14)	−0.0015 (16)
C14	0.0126 (14)	0.0270 (18)	0.039 (2)	−0.0078 (14)	−0.0066 (14)	−0.0059 (17)
C15	0.0178 (15)	0.0221 (16)	0.0191 (17)	−0.0106 (13)	−0.0006 (12)	−0.0040 (14)
C16	0.0193 (15)	0.0212 (16)	0.0197 (18)	−0.0089 (13)	−0.0010 (13)	0.0005 (14)
C17	0.0204 (17)	0.028 (2)	0.044 (3)	−0.0035 (15)	0.0017 (16)	−0.0131 (19)
C18	0.033 (2)	0.030 (2)	0.044 (3)	−0.0073 (17)	0.0045 (19)	−0.017 (2)
C19	0.0176 (17)	0.049 (3)	0.058 (3)	−0.0126 (18)	0.0003 (18)	−0.020 (2)

Geometric parameters (Å, º)

Br1—C2	1.973 (3)	C7—H7B	0.9900
Br2—C5	1.896 (3)	C8—H8A	0.9800
Br3—C12	1.974 (3)	C8—H8B	0.9800
Br4—C15	1.891 (3)	C8—H8C	0.9800
O1—C4	1.468 (5)	C9—H9A	0.9800
O1—C1	1.346 (4)	C9—H9B	0.9800
O2—C6	1.217 (5)	C9—H9C	0.9800
O3—C7	1.458 (6)	C11—C12	1.503 (5)
O3—C6	1.333 (5)	C11—C15	1.352 (6)
O4—C14	1.485 (5)	C12—C13	1.520 (6)
O4—C11	1.345 (4)	C13—C14	1.517 (6)
O5—C16	1.209 (5)	C14—C19	1.513 (7)
O6—C16	1.334 (4)	C15—C16	1.477 (5)
O6—C17	1.445 (5)	C17—C18	1.505 (6)
C1—C2	1.505 (5)	C12—H12A	1.0000
C1—C5	1.354 (6)	C13—H13A	0.9900
C2—C3	1.526 (6)	C13—H13B	0.9900
C3—C4	1.523 (5)	C14—H14A	1.0000
C4—C9	1.508 (6)	C17—H17A	0.9900
C5—C6	1.471 (5)	C17—H17B	0.9900
C7—C8	1.494 (7)	C18—H18A	0.9800
C2—H2A	1.0000	C18—H18B	0.9800
C3—H3B	0.9900	C18—H18C	0.9800
C3—H3A	0.9900	C19—H19A	0.9800
C4—H4A	1.0000	C19—H19B	0.9800
C7—H7A	0.9900	C19—H19C	0.9800
Br1···O1	3.507 (3)	C2···O3	2.788 (5)
Br1···O3	3.350 (3)	C3···O2^x	3.411 (5)
Br1···O5^i	3.220 (3)	C3···O2^i	3.321 (5)
Br1···C16^i	3.360 (3)	C4···O1^ix	3.284 (4)
Br2···O2	3.029 (3)	C5···C6^i	3.429 (5)
Br2···Br3^ii	3.5681 (7)	C5···C5^i	3.526 (5)
Br2···O1	2.957 (3)	C6···Br3^i	3.470 (4)
Br3···C6^i	3.470 (4)	C6···C1^i	3.468 (5)
Br3···O4	3.487 (3)	C6···C5^i	3.429 (5)
Br3···O2^i	3.425 (3)	C11···C16^vii	3.492 (4)
Br3···O6	3.392 (3)	C12···O6	2.766 (5)
Br3···Br2^iii	3.5681 (7)	C13···O5^vii	3.353 (5)
Br4···O5	3.022 (3)	C15···C15^vii	3.475 (5)
Br4···O4	2.984 (3)	C15···C16^vii	3.544 (5)
Br4···Br4^iv	3.6128 (7)	C16···C15^vii	3.544 (5)
Br1···H13B^v	3.0600	C16···Br1^i	3.360 (3)
Br1···H4A	3.2000	C16···C11^vii	3.492 (4)
Br2···H9C^vi	3.0700	C6···H2A	3.0300
Br2···H2A^i	3.1900	C16···H12A	3.0100
Br3···H14A	3.1200	H2A···C6	3.0300
Br4···H19A^vi	3.0500	H2A···O3	2.3600
Br4···H8B^i	3.2100	H2A···Br2^i	3.1900
Br4···H12A^vii	3.0600	H3A···H9A	2.4600
Br4···H19C^viii	3.1800	H3A···O2^i	2.5900
O1···Br2	2.957 (3)	H3A···H3A^v	2.4400
O1···C4^ix	3.284 (4)	H3B···O2^x	2.8700
O1···Br1	3.507 (3)	H3B···H18C^xi	2.5600
O2···Br2	3.029 (3)	H4A···O1^ix	2.7400
O2···C3^vi	3.411 (5)	H4A···Br1	3.2000
O2···Br3^i	3.425 (3)	H7A···O2	2.6600
O2···C1^i	3.336 (5)	H7B···O2	2.6300
O2···C3^i	3.321 (5)	H8B···Br4^i	3.2100
O3···Br1	3.350 (3)	H8C···H19B^xii	2.5900
O3···C2	2.788 (5)	H9A···H3A	2.4600
O4···Br4	2.984 (3)	H9B···O1^ix	2.7800
O4···Br3	3.487 (3)	H9C···Br2^x	3.0700
O5···C13^vii	3.353 (5)	H12A···O6	2.3000
O5···Br1^i	3.220 (3)	H12A···C16	3.0100
O5···Br4	3.022 (3)	H12A···Br4^vii	3.0600
O6···C12	2.766 (5)	H13A···H19B	2.4900
O6···Br3	3.392 (3)	H13A···O5^vii	2.5700
O1···H4A^ix	2.7400	H13B···Br1^v	3.0600
O1···H9B^ix	2.7800	H14A···Br3	3.1200
O2···H7B	2.6300	H14A···H18C^xiii	2.5600
O2···H7A	2.6600	H17A···O5	2.6900
O2···H3A^i	2.5900	H17B···O5	2.6000
O2···H3B^vi	2.8700	H17B···H19B^vii	2.4800
O3···H2A	2.3600	H18C···H14A^xiv	2.5600
O4···H19C^viii	2.8700	H18C···H3B^xi	2.5600
O5···H19A^vi	2.8900	H19A···Br4^x	3.0500
O5···H19B^vii	2.7800	H19A···O5^x	2.8900
O5···H13A^vii	2.5700	H19B···H8C^xv	2.5900
O5···H17A	2.6900	H19B···H13A	2.4900
O5···H17B	2.6000	H19B···O5^vii	2.7800
O6···H12A	2.3000	H19B···H17B^vii	2.4800
C1···C6^i	3.468 (5)	H19C···Br4^viii	3.1800
C1···O2^i	3.336 (5)	H19C···O4^viii	2.8700
C1—O1—C4	110.7 (3)	H9A—C9—H9B	109.00
C6—O3—C7	116.0 (3)	C4—C9—H9A	109.00
C11—O4—C14	110.2 (3)	O4—C11—C12	110.1 (3)
C16—O6—C17	116.5 (3)	O4—C11—C15	120.6 (3)
C2—C1—C5	129.4 (3)	C12—C11—C15	129.2 (3)
O1—C1—C5	120.2 (3)	Br3—C12—C11	107.8 (2)
O1—C1—C2	110.4 (3)	Br3—C12—C13	110.5 (3)
Br1—C2—C1	108.0 (2)	C11—C12—C13	102.0 (3)
Br1—C2—C3	110.5 (3)	C12—C13—C14	102.9 (3)
C1—C2—C3	101.8 (3)	O4—C14—C13	102.9 (3)
C2—C3—C4	103.3 (3)	O4—C14—C19	107.9 (4)
C3—C4—C9	115.1 (3)	C13—C14—C19	115.0 (4)
O1—C4—C3	103.4 (3)	Br4—C15—C11	118.6 (3)
O1—C4—C9	108.1 (4)	Br4—C15—C16	114.5 (3)
Br2—C5—C1	117.7 (3)	C11—C15—C16	127.0 (3)
Br2—C5—C6	114.9 (3)	O5—C16—O6	123.7 (3)
C1—C5—C6	127.4 (3)	O5—C16—C15	124.0 (3)
O2—C6—O3	124.0 (4)	O6—C16—C15	112.3 (3)
O3—C6—C5	112.4 (3)	O6—C17—C18	106.4 (4)
O2—C6—C5	123.7 (4)	Br3—C12—H12A	112.00
O3—C7—C8	106.8 (4)	C11—C12—H12A	112.00
C1—C2—H2A	112.00	C13—C12—H12A	112.00
C3—C2—H2A	112.00	C12—C13—H13A	111.00
Br1—C2—H2A	112.00	C12—C13—H13B	111.00
C4—C3—H3A	111.00	C14—C13—H13A	111.00
C2—C3—H3A	111.00	C14—C13—H13B	111.00
C2—C3—H3B	111.00	H13A—C13—H13B	109.00
H3A—C3—H3B	109.00	O4—C14—H14A	110.00
C4—C3—H3B	111.00	C13—C14—H14A	110.00
C3—C4—H4A	110.00	C19—C14—H14A	110.00
O1—C4—H4A	110.00	O6—C17—H17A	110.00
C9—C4—H4A	110.00	O6—C17—H17B	111.00
O3—C7—H7B	110.00	C18—C17—H17A	110.00
O3—C7—H7A	110.00	C18—C17—H17B	110.00
H7A—C7—H7B	109.00	H17A—C17—H17B	109.00
C8—C7—H7B	110.00	C17—C18—H18A	110.00
C8—C7—H7A	110.00	C17—C18—H18B	110.00
C7—C8—H8B	110.00	C17—C18—H18C	109.00
C7—C8—H8A	109.00	H18A—C18—H18B	109.00
H8A—C8—H8C	109.00	H18A—C18—H18C	109.00
C7—C8—H8C	109.00	H18B—C18—H18C	109.00
H8A—C8—H8B	109.00	C14—C19—H19A	109.00
H8B—C8—H8C	109.00	C14—C19—H19B	109.00
C4—C9—H9B	110.00	C14—C19—H19C	109.00
C4—C9—H9C	110.00	H19A—C19—H19B	109.00
H9A—C9—H9C	109.00	H19A—C19—H19C	109.00
H9B—C9—H9C	109.00	H19B—C19—H19C	109.00
C4—O1—C1—C2	−0.7 (4)	C1—C2—C3—C4	−30.4 (4)
C4—O1—C1—C5	177.6 (3)	C2—C3—C4—O1	30.6 (4)
C1—O1—C4—C3	−19.2 (4)	C2—C3—C4—C9	148.2 (3)
C1—O1—C4—C9	−141.6 (3)	Br2—C5—C6—O2	−4.4 (5)
C7—O3—C6—O2	−1.0 (6)	Br2—C5—C6—O3	175.9 (2)
C7—O3—C6—C5	178.6 (3)	C1—C5—C6—O2	176.1 (4)
C6—O3—C7—C8	−177.9 (4)	C1—C5—C6—O3	−3.5 (5)
C11—O4—C14—C13	−20.8 (4)	O4—C11—C12—Br3	−95.3 (3)
C14—O4—C11—C12	−0.3 (4)	O4—C11—C12—C13	21.1 (4)
C14—O4—C11—C15	177.6 (3)	C15—C11—C12—Br3	87.1 (4)
C11—O4—C14—C19	−142.8 (3)	C15—C11—C12—C13	−156.6 (4)
C16—O6—C17—C18	−176.2 (3)	O4—C11—C15—Br4	1.4 (4)
C17—O6—C16—O5	−0.2 (5)	O4—C11—C15—C16	179.7 (3)
C17—O6—C16—C15	180.0 (3)	C12—C11—C15—Br4	178.9 (3)
O1—C1—C2—Br1	−96.2 (3)	C12—C11—C15—C16	−2.9 (6)
C2—C1—C5—C6	−1.8 (6)	Br3—C12—C13—C14	81.9 (3)
O1—C1—C2—C3	20.1 (3)	C11—C12—C13—C14	−32.5 (4)
C5—C1—C2—Br1	85.8 (4)	C12—C13—C14—O4	32.6 (4)
C5—C1—C2—C3	−158.0 (3)	C12—C13—C14—C19	149.7 (4)
O1—C1—C5—Br2	0.8 (4)	Br4—C15—C16—O5	−0.5 (4)
O1—C1—C5—C6	−179.8 (3)	Br4—C15—C16—O6	179.4 (2)
C2—C1—C5—Br2	178.7 (3)	C11—C15—C16—O5	−178.9 (3)
Br1—C2—C3—C4	84.1 (3)	C11—C15—C16—O6	1.0 (5)

Symmetry codes: (i) −x, −y+1, −z+1; (ii) x, y−1, z; (iii) x, y+1, z; (iv) −x, −y+1, −z; (v) −x+1, −y+1, −z+1; (vi) x−1, y, z; (vii) −x, −y+2, −z; (viii) −x+1, −y+1, −z; (ix) −x+1, −y, −z+1; (x) x+1, y, z; (xi) −x, −y+2, −z+1; (xii) x−1, y, z+1; (xiii) x+1, y−1, z; (xiv) x−1, y+1, z; (xv) x+1, y, z−1.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C2—H2A···O3	1.00	2.36	2.788 (5)	105
C3—H3A···O2^i	0.99	2.59	3.321 (5)	131
C12—H12A···O6	1.00	2.30	2.766 (5)	107
C13—H13A···O5^vii	0.99	2.57	3.353 (5)	136

Symmetry codes: (i) −x, −y+1, −z+1; (vii) −x, −y+2, −z.