Ethyl (E)-2-methoxy­imino-2-(4-nitro­benzo­yl)acetate

Caracelli, I.; Moran, P.J.S.; Hinoue, L.; Zukerman-Schpector, J.; Tiekink, E.R.T.

doi:10.1107/S1600536810001583

organic compounds

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ISSN: 2056-9890

Volume 66| Part 2| February 2010| Page o396

https://doi.org/10.1107/S1600536810001583

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Ethyl (E)-2-methoxyimino-2-(4-nitrobenzoyl)acetate

Ignez Caracelli,^a ^* Paulo J. S. Moran,^b Luciana Hinoue,^b Julio Zukerman-Schpector ^c and Edward R. T. Tiekink ^d

^aBioMat-Physics Department, UNESP – Univ Estadual Paulista, 17033-360 Bauru, SP, Brazil, ^bInstituto de Química, Universidade Estadual de Campinas, CP 6154, 13083-970 Campinas, SP, Brazil, ^cDepartment of Chemistry, Universidade Federal de São Carlos, 13565-905 São Carlos, SP, Brazil, and ^dDepartment of Chemistry, University of Malaya, 50603 Kuala Lumpur, Malaysia
^*Correspondence e-mail: ignez@fc.unesp.br

(Received 7 January 2010; accepted 13 January 2010; online 20 January 2010)

The title molecule, C₁₂H₁₂N₂O₆, features an E conformation about the oxime group. The methoxyimino and ester residues are effectively coplanar with each other (r.m.s. deviation for the nine non-H atoms = 0.127 Å) and almost orthogonal [with dihedral angles of 99.44 (13) and −77.85 (13)°, respectively] to the carbonyl and nitrophenyl groups which lie to either side of this central plane. The crystal structure is consolidated by C—H⋯O contacts.

Related literature

For background to the synthesis of chiral hydroxyaminoacids and hydroxyaminoalcohols, see: Corrêa & Moran (1999 ); Kreutz et al. (1997 , 2000 ). For related structures, see: Caracelli et al. (2010 ); Forsyth et al. (2006 ); Ramos Silva et al. (2004 ). For the synthesis of the title compound, see: Buehler (1967 ).

Experimental

Crystal data

C₁₂H₁₂N₂O₆
M_r = 280.24
Triclinic, $[P \overline 1]$
a = 7.5197 (1) Å
b = 7.5793 (1) Å
c = 12.3338 (2) Å
α = 83.264 (1)°
β = 73.731 (1)°
γ = 68.939 (1)°
V = 629.62 (2) Å³
Z = 2
Mo Kα radiation
μ = 0.12 mm⁻¹
T = 100 K
0.35 × 0.25 × 0.08 mm

Data collection

Bruker APEXII CCD diffractometer
Absorption correction: multi scan (SADABS; Sheldrick, 1996 ) T_min = 0.933, T_max = 1.000
9325 measured reflections
2614 independent reflections
2310 reflections with I > 2σ(I)
R_int = 0.018

Refinement

R[F² > 2σ(F²)] = 0.031
wR(F²) = 0.088
S = 1.05
2614 reflections
183 parameters
H-atom parameters constrained
Δρ_max = 0.28 e Å⁻³
Δρ_min = −0.24 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C2—H2⋯O4ⁱ	0.93	2.56	3.3853 (14)	148
C3—H3⋯O2ⁱⁱ	0.93	2.50	3.3950 (16)	162
C5—H5⋯O5ⁱⁱⁱ	0.93	2.35	3.1856 (14)	150
C6—H6⋯O3^iv	0.93	2.46	3.3514 (16)	160
Symmetry codes: (i) -x+1, -y+1, -z+1; (ii) x-1, y, z; (iii) -x+2, -y+1, -z; (iv) x+1, y, z.

Data collection: APEX2 (Bruker, 2007 ); cell refinement: SAINT (Bruker, 2007); data reduction: SAINT; program(s) used to solve structure: SIR97 (Altomare et al., 1999 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ); molecular graphics: ORTEP-3 (Farrugia, 1997 ) and DIAMOND (Brandenburg, 2006 ); software used to prepare material for publication: WinGX (Farrugia, 1999 ), PARST (Nardelli, 1995 ) and publCIF (Westrip, 2010 ).

Supporting information

Crystal structure: contains datablocks I, global. DOI: https://doi.org/10.1107/S1600536810001583/su2157sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536810001583/su2157Isup2.hkl

checkCIF report

Comment top

In connection with studies involving the synthesis of chiral hydroxyaminoacids and hydroxyaminoalcohols, whereby α-ketomethoxyimino compounds are reduced by sodium borohydride (Corrêa & Moran, 1999) and enantioselectively bio-reduced by whole cells of yeast (Kreutz et al., 1997; Kreutz et al., 2000), the title compound was prepared as an intermediary.

The molecular structure of the title compound is illustrated in Fig. 1, and the geometrical parameters are given in the Supplementary information and the archived CIF. The conformation about the oxime bond [N2═C8 = 1.2790 (14) Å] is E. The methoxyimino moiety is effectively co-planar with the ester group, as seen in the sequence of O4-N2-C8-C9, N2-C8-C9-O5 and C8-C9-O6-C10 torsion angles of 177.54 (8), 6.76 (16) and 178.40 (9) °, respectively. While atom C7 lies in the mean plane of the ester group [O4-N2-C8-C7 = 2.17 (14) °], the carbonyl and nitrophenyl groups occupy positions almost orthogonal to the remaining atoms, as seen in the values of the N2-C8-C7-O3 and N2-C8-C7-C4 torsion angles of 99.44 (13) and -77.85 (13) °, respectively. The nitro group and the benzene ring to which it is attached are slightly twisted with respect to one another, with a dihedral angle of 8.54 (8)°. Globally, when viewed down the C7–C8 bond, the carbonyl-O3 atom lies to one side of the central plane and the nitrophenyl group to the other.

The crystal packing is dominated by C–H(aromatic)···O interactions involving the nitro-O2, carbonyl-O3 and oxime-O4 atoms to form layers in the ab plane (Table 1 and Fig. 2). These layers stack along [001] with interdigitation of the ethyl ester groups (Fig. 3), and C–H···O interactions involving the ester carbonyl-O5 atom.

The basic C(═O)C(═NOH)C(═O)OC framework in the title compound is comparatively rare with only three other structures reported, namely the recently described Z-isomer of the title compound (Caracelli et al., 2010), 2-(hydroxyimino)-3-oxo-3-phenylpropionate, where E-conformations are found for each of the independent molecules (Ramos Silva et al., 2004), and benzyl 2-(hydroxyimino)acetoacetate, for which a Z conformation is found (Forsyth et al., 2006).

Related literature top

For background to the synthesis of chiral hydroxyaminoacids and hydroxyaminoalcohols, see: Corrêa & Moran (1999); Kreutz et al. (1997); Kreutz et al. (2000). For related structures, see: Caracelli et al. (2010); Forsyth et al. (2006); Ramos Silva et al. (2004). For the synthesis of the title compound, see: Buehler (1967).

Experimental top

The title compound was prepared following a modified literature method (Buehler, 1967). Silver oxide (1.3 mmol) was slowly added with stirring to a solution of a mixture of ethyl (E)- and (Z)-2-hydroximino-3-(4-nitrophenyl)-3-oxopropanoate (2.25 mmol) and methyl iodide (5.6 mmol) in CH₂Cl₂ (30 ml), and cooled in a ice-water bath. The temperature was then raised to 301 K and the stirring maintained for 1 h. The precipitate formed was filtered off and washed with CH₂Cl₂. The solvent was evaporated to afford yellow crystals of a mixture of E:Z (90:10) isomers in 86% yield. They were separated by TLC chromatography on silica gel with 5% ethyl acetate/hexane. The principal fraction was shown by crystallographic analysis to be the E isomer; m.p. 367.6–368.0 K.

Structure description top

Computing details top

Data collection: APEX2 (Bruker, 2007); cell refinement: SAINT (Bruker, 2007); data reduction: SAINT (Bruker, 2007); program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997) and DIAMOND (Brandenburg, 2006); software used to prepare material for publication: WinGX (Farrugia, 1999), PARST (Nardelli, 1995) and publCIF (Westrip, 2010).

Figures top

	Fig. 1. Molecular structure of the title compound, showing the atom labelling scheme and displacement ellipsoids at the 50% probability level (arbitrary spheres for the H atoms).
	Fig. 2. A view of the layer structure in the title compound, sustained by C–H···O contacts [the C–H···O contacts are shown as brown dashed lines; colour code: O, red; N, blue; C, grey; H, green].
	Fig. 3. A view along the b axis of the crystal packing of the title compound, highlighting the interdigitation of the ester groups [the C–H···O contacts are shown as brown dashed lines; colour code: O, red; N, blue; C, grey; H, green].

Ethyl (E)-2-methoxyimino-2-(4-nitrobenzoyl)acetate top

Crystal data top

C₁₂H₁₂N₂O₆	Z = 2
M_r = 280.24	F(000) = 292
Triclinic, P1	D_x = 1.478 Mg m⁻³
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 7.5197 (1) Å	Cell parameters from 5430 reflections
b = 7.5793 (1) Å	θ = 26.6–2.9°
c = 12.3338 (2) Å	µ = 0.12 mm⁻¹
α = 83.264 (1)°	T = 100 K
β = 73.731 (1)°	Block, pale-yellow
γ = 68.939 (1)°	0.35 × 0.25 × 0.08 mm
V = 629.62 (2) Å³

Data collection top

Bruker APEXII CCD diffractometer	2614 independent reflections
Radiation source: fine-focus sealed tube	2310 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.018
φ and ω scans	θ_max = 26.6°, θ_min = 1.7°
Absorption correction: multi scan (SADABS; Sheldrick, 1996)	h = −9→9
T_min = 0.933, T_max = 1.000	k = −9→9
9325 measured reflections	l = −15→15

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.031	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.088	H-atom parameters constrained
S = 1.05	w = 1/[σ²(F_o²) + (0.0456P)² + 0.1834P] where P = (F_o² + 2F_c²)/3
2614 reflections	(Δ/σ)_max = 0.001
183 parameters	Δρ_max = 0.28 e Å⁻³
0 restraints	Δρ_min = −0.24 e Å⁻³

Crystal data top

C₁₂H₁₂N₂O₆	γ = 68.939 (1)°
M_r = 280.24	V = 629.62 (2) Å³
Triclinic, P1	Z = 2
a = 7.5197 (1) Å	Mo Kα radiation
b = 7.5793 (1) Å	µ = 0.12 mm⁻¹
c = 12.3338 (2) Å	T = 100 K
α = 83.264 (1)°	0.35 × 0.25 × 0.08 mm
β = 73.731 (1)°

Data collection top

Bruker APEXII CCD diffractometer	2614 independent reflections
Absorption correction: multi scan (SADABS; Sheldrick, 1996)	2310 reflections with I > 2σ(I)
T_min = 0.933, T_max = 1.000	R_int = 0.018
9325 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.031	0 restraints
wR(F²) = 0.088	H-atom parameters constrained
S = 1.05	Δρ_max = 0.28 e Å⁻³
2614 reflections	Δρ_min = −0.24 e Å⁻³
183 parameters

Special details top

Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'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 > 2σ(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

	x	y	z	U_iso*/U_eq
C1	0.95878 (16)	0.26376 (14)	0.48218 (9)	0.0180 (2)
C2	0.77279 (16)	0.24949 (15)	0.51100 (9)	0.0190 (2)
H2	0.7241	0.2000	0.5810	0.023*
C3	0.66149 (16)	0.31060 (15)	0.43316 (9)	0.0185 (2)
H3	0.5370	0.3003	0.4498	0.022*
C4	0.73587 (16)	0.38808 (14)	0.32919 (9)	0.0174 (2)
C5	0.92289 (16)	0.40168 (15)	0.30321 (9)	0.0195 (2)
H5	0.9711	0.4539	0.2341	0.023*
C6	1.03760 (16)	0.33776 (15)	0.37975 (9)	0.0195 (2)
H6	1.1636	0.3444	0.3628	0.023*
C7	0.60888 (16)	0.45924 (14)	0.24893 (9)	0.0173 (2)
C8	0.67583 (15)	0.57310 (15)	0.14594 (9)	0.0175 (2)
C9	0.75507 (16)	0.49578 (15)	0.02915 (9)	0.0192 (2)
C10	0.81887 (17)	0.23916 (16)	−0.08355 (9)	0.0209 (2)
H10B	0.9588	0.2169	−0.1133	0.025*
H10A	0.7494	0.3237	−0.1353	0.025*
C11	0.78050 (19)	0.05568 (16)	−0.07074 (10)	0.0251 (3)
H11B	0.8255	−0.0029	−0.1430	0.038*
H11C	0.6416	0.0794	−0.0416	0.038*
H11A	0.8499	−0.0268	−0.0194	0.038*
C12	0.55476 (19)	1.00856 (16)	0.25880 (10)	0.0243 (3)
H12C	0.4759	1.0782	0.2084	0.036*
H12A	0.6827	1.0209	0.2336	0.036*
H12B	0.4920	1.0575	0.3336	0.036*
N2	0.65628 (13)	0.74693 (13)	0.15091 (8)	0.0189 (2)
N1	1.07936 (14)	0.19686 (13)	0.56457 (8)	0.0204 (2)
O6	0.74864 (12)	0.32311 (11)	0.02858 (6)	0.02006 (19)
O5	0.81359 (14)	0.58238 (12)	−0.05260 (7)	0.0283 (2)
O3	0.45219 (12)	0.43609 (11)	0.26469 (7)	0.02198 (19)
O4	0.57531 (12)	0.81146 (11)	0.26006 (6)	0.0221 (2)
O1	1.00183 (13)	0.15085 (13)	0.65930 (7)	0.0300 (2)
O2	1.25168 (13)	0.18865 (13)	0.53367 (7)	0.0285 (2)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
C1	0.0223 (6)	0.0154 (5)	0.0157 (5)	−0.0056 (4)	−0.0047 (4)	−0.0012 (4)
C2	0.0233 (6)	0.0175 (5)	0.0144 (5)	−0.0084 (4)	−0.0006 (4)	0.0004 (4)
C3	0.0184 (5)	0.0185 (5)	0.0182 (5)	−0.0086 (4)	−0.0006 (4)	−0.0011 (4)
C4	0.0208 (5)	0.0153 (5)	0.0154 (5)	−0.0070 (4)	−0.0021 (4)	−0.0012 (4)
C5	0.0215 (5)	0.0202 (5)	0.0156 (5)	−0.0092 (4)	−0.0014 (4)	0.0021 (4)
C6	0.0180 (5)	0.0209 (5)	0.0194 (5)	−0.0087 (4)	−0.0020 (4)	0.0001 (4)
C7	0.0196 (5)	0.0155 (5)	0.0154 (5)	−0.0069 (4)	−0.0005 (4)	−0.0020 (4)
C8	0.0168 (5)	0.0200 (5)	0.0168 (5)	−0.0082 (4)	−0.0042 (4)	0.0016 (4)
C9	0.0192 (5)	0.0209 (5)	0.0182 (5)	−0.0079 (4)	−0.0048 (4)	0.0009 (4)
C10	0.0250 (6)	0.0227 (5)	0.0151 (5)	−0.0090 (4)	−0.0040 (4)	−0.0010 (4)
C11	0.0329 (7)	0.0234 (6)	0.0217 (6)	−0.0122 (5)	−0.0080 (5)	−0.0004 (5)
C12	0.0306 (6)	0.0174 (5)	0.0252 (6)	−0.0089 (5)	−0.0062 (5)	−0.0017 (4)
N2	0.0200 (5)	0.0212 (5)	0.0156 (5)	−0.0081 (4)	−0.0036 (4)	−0.0003 (4)
N1	0.0239 (5)	0.0198 (5)	0.0178 (5)	−0.0080 (4)	−0.0050 (4)	−0.0001 (4)
O6	0.0259 (4)	0.0197 (4)	0.0152 (4)	−0.0102 (3)	−0.0029 (3)	−0.0004 (3)
O5	0.0416 (5)	0.0267 (4)	0.0174 (4)	−0.0187 (4)	−0.0005 (4)	0.0013 (3)
O3	0.0217 (4)	0.0246 (4)	0.0219 (4)	−0.0121 (3)	−0.0051 (3)	0.0028 (3)
O4	0.0302 (4)	0.0188 (4)	0.0166 (4)	−0.0104 (3)	−0.0016 (3)	−0.0017 (3)
O1	0.0309 (5)	0.0414 (5)	0.0160 (4)	−0.0132 (4)	−0.0049 (4)	0.0057 (4)
O2	0.0245 (4)	0.0382 (5)	0.0269 (5)	−0.0153 (4)	−0.0094 (4)	0.0058 (4)

Geometric parameters (Å, º) top

C1—C6	1.3839 (15)	C9—O5	1.2020 (14)
C1—C2	1.3839 (16)	C9—O6	1.3278 (13)
C1—N1	1.4753 (14)	C10—O6	1.4670 (13)
C2—C3	1.3798 (16)	C10—C11	1.5011 (16)
C2—H2	0.9300	C10—H10B	0.9700
C3—C4	1.4000 (15)	C10—H10A	0.9700
C3—H3	0.9300	C11—H11B	0.9600
C4—C5	1.3910 (16)	C11—H11C	0.9600
C4—C7	1.4889 (15)	C11—H11A	0.9600
C5—C6	1.3851 (16)	C12—O4	1.4442 (13)
C5—H5	0.9300	C12—H12C	0.9600
C6—H6	0.9300	C12—H12A	0.9600
C7—O3	1.2121 (14)	C12—H12B	0.9600
C7—C8	1.5194 (14)	N2—O4	1.3797 (12)
C8—N2	1.2790 (14)	N1—O1	1.2229 (12)
C8—C9	1.4965 (15)	N1—O2	1.2244 (13)

C6—C1—C2	123.25 (10)	O6—C9—C8	111.19 (9)
C6—C1—N1	118.25 (10)	O6—C10—C11	107.57 (9)
C2—C1—N1	118.51 (9)	O6—C10—H10B	110.2
C3—C2—C1	118.23 (10)	C11—C10—H10B	110.2
C3—C2—H2	120.9	O6—C10—H10A	110.2
C1—C2—H2	120.9	C11—C10—H10A	110.2
C2—C3—C4	120.00 (10)	H10B—C10—H10A	108.5
C2—C3—H3	120.0	C10—C11—H11B	109.5
C4—C3—H3	120.0	C10—C11—H11C	109.5
C5—C4—C3	120.30 (10)	H11B—C11—H11C	109.5
C5—C4—C7	121.09 (10)	C10—C11—H11A	109.5
C3—C4—C7	118.59 (10)	H11B—C11—H11A	109.5
C6—C5—C4	120.29 (10)	H11C—C11—H11A	109.5
C6—C5—H5	119.9	O4—C12—H12C	109.5
C4—C5—H5	119.9	O4—C12—H12A	109.5
C1—C6—C5	117.91 (10)	H12C—C12—H12A	109.5
C1—C6—H6	121.0	O4—C12—H12B	109.5
C5—C6—H6	121.0	H12C—C12—H12B	109.5
O3—C7—C4	122.79 (10)	H12A—C12—H12B	109.5
O3—C7—C8	119.12 (10)	C8—N2—O4	111.55 (9)
C4—C7—C8	118.03 (9)	O1—N1—O2	123.89 (10)
N2—C8—C9	114.45 (9)	O1—N1—C1	118.03 (9)
N2—C8—C7	122.66 (9)	O2—N1—C1	118.08 (9)
C9—C8—C7	122.72 (9)	C9—O6—C10	114.57 (8)
O5—C9—O6	125.40 (10)	N2—O4—C12	108.40 (8)
O5—C9—C8	123.40 (10)

C6—C1—C2—C3	0.61 (16)	O3—C7—C8—C9	−75.55 (14)
N1—C1—C2—C3	−179.38 (9)	C4—C7—C8—C9	107.17 (12)
C1—C2—C3—C4	−1.27 (15)	N2—C8—C9—O5	6.76 (16)
C2—C3—C4—C5	0.82 (16)	C7—C8—C9—O5	−177.87 (11)
C2—C3—C4—C7	−177.73 (9)	N2—C8—C9—O6	−172.26 (9)
C3—C4—C5—C6	0.35 (16)	C7—C8—C9—O6	3.10 (14)
C7—C4—C5—C6	178.85 (10)	C9—C8—N2—O4	177.54 (8)
C2—C1—C6—C5	0.52 (16)	C7—C8—N2—O4	2.17 (14)
N1—C1—C6—C5	−179.49 (9)	C6—C1—N1—O1	172.19 (10)
C4—C5—C6—C1	−0.99 (16)	C2—C1—N1—O1	−7.82 (14)
C5—C4—C7—O3	173.89 (10)	C6—C1—N1—O2	−8.63 (15)
C3—C4—C7—O3	−7.58 (16)	C2—C1—N1—O2	171.36 (10)
C5—C4—C7—C8	−8.93 (15)	O5—C9—O6—C10	−0.60 (16)
C3—C4—C7—C8	169.60 (9)	C8—C9—O6—C10	178.40 (9)
O3—C7—C8—N2	99.44 (13)	C11—C10—O6—C9	−173.74 (9)
C4—C7—C8—N2	−77.85 (13)	C8—N2—O4—C12	−179.06 (9)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C2—H2···O4ⁱ	0.93	2.56	3.3853 (14)	148
C3—H3···O2ⁱⁱ	0.93	2.50	3.3950 (16)	162
C5—H5···O5ⁱⁱⁱ	0.93	2.35	3.1856 (14)	150
C6—H6···O3^iv	0.93	2.46	3.3514 (16)	160

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

Experimental details

Crystal data
Chemical formula	C₁₂H₁₂N₂O₆
M_r	280.24
Crystal system, space group	Triclinic, P1
Temperature (K)	100
a, b, c (Å)	7.5197 (1), 7.5793 (1), 12.3338 (2)
α, β, γ (°)	83.264 (1), 73.731 (1), 68.939 (1)
V (Å³)	629.62 (2)
Z	2
Radiation type	Mo Kα
µ (mm⁻¹)	0.12
Crystal size (mm)	0.35 × 0.25 × 0.08

Data collection
Diffractometer	Bruker APEXII CCD
Absorption correction	Multi scan (SADABS; Sheldrick, 1996)
T_min, T_max	0.933, 1.000
No. of measured, independent and observed [I > 2σ(I)] reflections	9325, 2614, 2310
R_int	0.018
(sin θ/λ)_max (Å⁻¹)	0.630

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.031, 0.088, 1.05
No. of reflections	2614
No. of parameters	183
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.28, −0.24

Computer programs: APEX2 (Bruker, 2007), SAINT (Bruker, 2007), SIR97 (Altomare et al., 1999), SHELXL97 (Sheldrick, 2008), ORTEP-3 (Farrugia, 1997) and DIAMOND (Brandenburg, 2006), WinGX (Farrugia, 1999), PARST (Nardelli, 1995) and publCIF (Westrip, 2010).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C2—H2···O4ⁱ	0.93	2.56	3.3853 (14)	148
C3—H3···O2ⁱⁱ	0.93	2.50	3.3950 (16)	162
C5—H5···O5ⁱⁱⁱ	0.93	2.35	3.1856 (14)	150
C6—H6···O3^iv	0.93	2.46	3.3514 (16)	160

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

Acknowledgements

We thank FAPESP, CNPq and CAPES for financial support.

References

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