(1S,3R,8R,11S)-11-Bromo-10-bromo­methyl-2,2-di­chloro-3,7,7-tri­methyl­tricyclo­[6.4.0.01,3]dodec-9-ene

Benharref, A.; El karroumi, J.; El Ammari, L.; Saadi, M.; Berraho, M.

doi:10.1107/S1600536813019697

organic compounds

CRYSTALLOGRAPHIC
COMMUNICATIONS

ISSN: 2056-9890

Volume 69| Part 8| August 2013| Page o1283

doi:10.1107/S1600536813019697

Open

access

(1S,3R,8R,11S)-11-Bromo-10-bromomethyl-2,2-dichloro-3,7,7-trimethyltricyclo[6.4.0.0^1,3]dodec-9-ene

Ahmed Benharref,^a Jamal El karroumi,^a ^* Lahcen El Ammari,^b Mohamed Saadi ^c and Moha Berraho ^a

^aLaboratoire de Chimie des Substances Naturelles, "Unité Associé au CNRST (URAC16)", Faculté des Sciences Semlalia, BP 2390 Bd My Abdellah, 40000 Marrakech, Morocco, ^bLaboratoire de Chimie du Solide, Appliquée, Faculté des Sciences, Université MohammedV-Agdal , Avenue Ibn Battouta, BP 1014, Rabat, Morocco, and ^cLaboratoire de Chimie du Solide, Appliquée, Faculté des Sciences, Université MohammedV-Agdal, Avenue Ibn Battouta, BP 1014, Rabat, Morocco
^*Correspondence e-mail: berraho@uca.ma

(Received 15 July 2013; accepted 16 July 2013; online 20 July 2013)

The title compound, C₁₆H₂₂Br₂Cl₂, was synthesized from β-himachalene (3,5,5,9-tetramethyl-2,4a,5,6,7,8-hexahydro-1H-benzocycloheptene), which was isolated from the essential oil of the Atlas cedar (Cedrus Atlantica). The molecule is built up from fused six- and seven-membered rings and an appended three-membered ring. The six-membered ring has a half-chair conformation, whereas the seven-membered ring displays a chair conformation. The dihedral angle between the two best plane through each ring is 59.5 (2)°. No specific intermolecular interactions were discerned in the crystal packing.

Related literature

For the reactivity and biological properties of β-himachalene, see: El Haib et al. (2011 ); El Jamili et al. (2002 ); Daoubi et al. (2004 ). For related structures, see: Oukhrib et al. (2013 ); Ourhriss et al. (2013 ); Benharref et al.(2013 ). For puckering parameters, see: Cremer & Pople (1975 ).

Experimental

Crystal data

C₁₆H₂₂Br₂Cl₂
M_r = 445.06
Orthorhombic, P 2₁ 2₁ 2₁
a = 8.2594 (7) Å
b = 13.0352 (11) Å
c = 16.6241 (13) Å
V = 1789.8 (3) Å³
Z = 4
Mo Kα radiation
μ = 4.82 mm⁻¹
T = 293 K
0.20 × 0.15 × 0.12 mm

Data collection

Bruker APEXII CCD diffractometer
Absorption correction: multi-scan (SHELXS97; Sheldrick,2008 ) T_min = 0.423, T_max = 0.617
10693 measured reflections
3654 independent reflections
3183 reflections with I > 2σ(I)
R_int = 0.026

Refinement

R[F² > 2σ(F²)] = 0.038
wR(F²) = 0.102
S = 1.05
3654 reflections
184 parameters
H-atom parameters constrained
Δρ_max = 0.55 e Å⁻³
Δρ_min = −0.54 e Å⁻³
Absolute structure: Flack & Bernardinelli (2000 ), 614 Friedel pairs
Absolute structure parameter: 0.022 (13)

Data collection: APEX2 (Bruker, 2009 ); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012 ); software used to prepare material for publication: WinGX (Farrugia, 2012).

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536813019697/tk5241sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536813019697/tk5241Isup2.hkl

Supporting information file. DOI: 10.1107/S1600536813019697/tk5241Isup3.cml

checkCIF report

Comment top

The bicyclic sesquiterpene β-himachalene is the main constituent (50%) of the essential oil of the Atlas cedar (Cedrus atlantica) (El Haib et al., 2011). The reactivity of this sesquiterpene and its derivatives has been studied extensively by our team in order to prepare new products having biological proprieties (El Jamili et al., 2002; Daoubi et al., 2004; Ourhriss et al., 2013; Oukhrib et al., 2013; Benharref et al., 2013). In this work, we present the crystal structure of the title compound, (1S,3R,8R,11S)- 10- bromomethyl-11-bromo-2,2-dichloro-3,7,7-trimethyltricyclo [6.4.0.0₁,₃] dodec-9-ene. The molecule contains fused six-and seven-membered rings, which is fused to a three-membered ring as shown in Fig. 1. The six-membered ring has a half-chair conformation, as indicated by the total puckering amplitude QT = 0.466 (4) Å and spherical polar angle θ = 129.9 (7)° with ϕ = 152.5 (7)°, whereas the seven-membered ring displays a chair conformation with QT = 0.8129 (51) Å, θ = 32.71 (40)°, ϕ2 = -46.29 (5)° and ϕ3 = -77.86 (39)° (Cremer & Pople, 1975). Owing to the presence of Br atoms, the absolute configuration could be fully confirmed, by refining the Flack parameter (Flack & Bernardinelli, 2000) as C1(S), C3(R), C8(R) and C11(S).

Related literature top

For the reactivity and biological properties of β-himachalene, see: El Haib et al. (2011); El Jamili et al. (2002); Daoubi et al. (2004). For related structures, see: Oukhrib et al. (2013); Ourhriss et al. (2013); Benharref et al.(2013). For puckering parameters, see: Cremer & Pople (1975).

Experimental top

In a reactor equipped with a stirrer, a condenser, a dropping funnel and a thermometer containing (1S,3R,8R)-2,2-dichloro-3,7,7,10-tetramethyltricyclo [6.4.0.01,3] dodec-9-ene (2 g, 7 mmol) (El Jamili et al., 2002) and carbon tetrachloride (60 ml) was added slowly over an 1.5 h by heating and stirring a solution of bromine (1.6 g, 10 mmol) in carbon tetrachloride (5 ml). Heating and stirring were maintained for 1 h after the addition of bromine. Thereafter the reaction mixture was cooled and concentrated to evaporate the carbon tetrachloride. the residue obtained was chromatographed on silica eluting with hexane, which allowed the isolation of pure (1S,3R,8R,11S)-10-bromomethyl-11-bromo-2,2-dichloro-3,7,7-trimethyltricyclo [6.4.0.01,3] dodec-9-ene in a yield of 20% (623 mg, 1.4 mmol). The title compound was recrystallized from its hexane solution.

Computing details top

Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT (Bruker, 2009); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012); software used to prepare material for publication: WinGX (Farrugia, 2012).

Figures top

Fig. 1. Molecular structure of the title compound with the atom-labelling scheme. Displacement ellipsoids are drawn at the 30% probability. level. H atoms are represented as small spheres of arbitrary radii.

(1S,3R,8R,11S)-11-Bromo-10-bromomethyl-2,2-dichloro-3,7,7-trimethyltricyclo[6.4.0.0^1,3]dodec-9-ene top

Crystal data top

C₁₆H₂₂Br₂Cl₂	F(000) = 888
M_r = 445.06	D_x = 1.652 Mg m⁻³
Orthorhombic, P2₁2₁2₁	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2ab	Cell parameters from 3653 reflections
a = 8.2594 (7) Å	θ = 2.8–26.4°
b = 13.0352 (11) Å	µ = 4.82 mm⁻¹
c = 16.6241 (13) Å	T = 293 K
V = 1789.8 (3) Å³	Block, colourless
Z = 4	0.20 × 0.15 × 0.12 mm

Data collection top

Bruker APEXII CCD diffractometer	3654 independent reflections
Radiation source: fine-focus sealed tube	3183 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.026
ω and ϕ scans	θ_max = 26.4°, θ_min = 2.5°
Absorption correction: multi-scan SHELXS97 (Sheldrick,2008)	h = −10→10
T_min = 0.423, T_max = 0.617	k = −13→16
10693 measured reflections	l = −11→20

Refinement top

Refinement on F²	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F² > 2σ(F²)] = 0.038	H-atom parameters constrained
wR(F²) = 0.102	w = 1/[σ²(F_o²) + (0.0406P)² + 1.2463P] where P = (F_o² + 2F_c²)/3
S = 1.05	(Δ/σ)_max < 0.001
3654 reflections	Δρ_max = 0.55 e Å⁻³
184 parameters	Δρ_min = −0.54 e Å⁻³
0 restraints	Absolute structure: Flack & Bernardinelli (2000), 614 Friedel pairs
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: 0.022 (13)

Crystal data top

C₁₆H₂₂Br₂Cl₂	V = 1789.8 (3) Å³
M_r = 445.06	Z = 4
Orthorhombic, P2₁2₁2₁	Mo Kα radiation
a = 8.2594 (7) Å	µ = 4.82 mm⁻¹
b = 13.0352 (11) Å	T = 293 K
c = 16.6241 (13) Å	0.20 × 0.15 × 0.12 mm

Data collection top

Bruker APEXII CCD diffractometer	3654 independent reflections
Absorption correction: multi-scan SHELXS97 (Sheldrick,2008)	3183 reflections with I > 2σ(I)
T_min = 0.423, T_max = 0.617	R_int = 0.026
10693 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.038	H-atom parameters constrained
wR(F²) = 0.102	Δρ_max = 0.55 e Å⁻³
S = 1.05	Δρ_min = −0.54 e Å⁻³
3654 reflections	Absolute structure: Flack & Bernardinelli (2000), 614 Friedel pairs
184 parameters	Absolute structure parameter: 0.022 (13)
0 restraints

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	0.3469 (4)	0.4202 (3)	0.7271 (2)	0.0346 (8)
C2	0.1795 (4)	0.3776 (4)	0.7462 (3)	0.0440 (9)
C3	0.2012 (4)	0.4409 (4)	0.6715 (2)	0.0446 (9)
C4	0.1967 (6)	0.3884 (4)	0.5903 (3)	0.0570 (12)
H4A	0.0915	0.3999	0.5659	0.068*
H4B	0.2095	0.3151	0.5979	0.068*
C5	0.3291 (6)	0.4270 (5)	0.5327 (3)	0.0598 (13)
H5A	0.2927	0.4188	0.4775	0.072*
H5B	0.3480	0.4994	0.5421	0.072*
C6	0.4858 (7)	0.3684 (5)	0.5444 (3)	0.0721 (15)
H6A	0.5565	0.3853	0.4998	0.086*
H6B	0.4610	0.2959	0.5401	0.086*
C7	0.5838 (5)	0.3841 (3)	0.6231 (2)	0.0446 (9)
C8	0.4798 (5)	0.3470 (3)	0.6986 (2)	0.0354 (8)
H8	0.4247	0.2840	0.6817	0.043*
C9	0.5846 (5)	0.3179 (3)	0.7684 (2)	0.0384 (8)
H9	0.6527	0.2619	0.7611	0.046*
C10	0.5903 (4)	0.3636 (3)	0.8394 (2)	0.0373 (8)
C11	0.4874 (5)	0.4553 (3)	0.8571 (2)	0.0370 (8)
H11	0.4009	0.4346	0.8940	0.044*
C12	0.4109 (5)	0.5026 (3)	0.7827 (2)	0.0391 (8)
H12A	0.3228	0.5475	0.7987	0.047*
H12B	0.4908	0.5436	0.7545	0.047*
C13	0.1283 (6)	0.5488 (4)	0.6685 (3)	0.0684 (14)
H13A	0.1301	0.5784	0.7214	0.103*
H13B	0.0185	0.5448	0.6498	0.103*
H13C	0.1904	0.5907	0.6325	0.103*
C14	0.7278 (9)	0.3099 (6)	0.6141 (4)	0.093 (2)
H14A	0.8067	0.3242	0.6550	0.139*
H14B	0.7761	0.3188	0.5620	0.139*
H14C	0.6904	0.2406	0.6196	0.139*
C15	0.6474 (9)	0.4891 (5)	0.6292 (4)	0.0845 (19)
H15A	0.5591	0.5365	0.6345	0.127*
H15B	0.7083	0.5052	0.5816	0.127*
H15C	0.7165	0.4943	0.6754	0.127*
C16	0.6964 (5)	0.3222 (4)	0.9042 (3)	0.0507 (10)
H16A	0.7645	0.3769	0.9247	0.061*
H16B	0.7665	0.2698	0.8817	0.061*
Cl3	0.14150 (16)	0.24471 (10)	0.74083 (8)	0.0694 (3)
Cl4	0.06998 (15)	0.42878 (14)	0.82812 (8)	0.0734 (4)
Br1	0.61787 (8)	0.56321 (4)	0.90951 (3)	0.07068 (18)
Br2	0.57150 (8)	0.26329 (6)	0.99305 (4)	0.0885 (2)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
C1	0.0338 (17)	0.035 (2)	0.0352 (18)	−0.0032 (15)	−0.0007 (13)	0.0027 (15)
C2	0.0327 (18)	0.053 (3)	0.046 (2)	−0.0103 (17)	0.0056 (15)	0.0024 (19)
C3	0.0342 (18)	0.051 (2)	0.048 (2)	−0.0075 (18)	−0.0073 (15)	0.010 (2)
C4	0.051 (2)	0.076 (3)	0.045 (2)	−0.021 (2)	−0.0154 (19)	0.004 (2)
C5	0.066 (3)	0.080 (3)	0.033 (2)	−0.020 (3)	−0.0090 (18)	0.011 (2)
C6	0.075 (3)	0.091 (4)	0.051 (3)	−0.017 (3)	0.001 (2)	−0.001 (3)
C7	0.045 (2)	0.055 (2)	0.0338 (19)	−0.007 (2)	0.0081 (16)	−0.0015 (17)
C8	0.0395 (19)	0.033 (2)	0.0341 (19)	−0.0040 (15)	0.0043 (14)	−0.0020 (15)
C9	0.0385 (19)	0.0315 (19)	0.045 (2)	0.0062 (15)	0.0033 (16)	0.0031 (16)
C10	0.0346 (18)	0.040 (2)	0.0373 (19)	−0.0006 (16)	0.0011 (15)	0.0059 (16)
C11	0.0401 (19)	0.037 (2)	0.0336 (19)	0.0006 (15)	0.0026 (14)	−0.0077 (16)
C12	0.040 (2)	0.036 (2)	0.041 (2)	0.0055 (16)	−0.0017 (16)	−0.0041 (16)
C13	0.052 (3)	0.075 (4)	0.079 (3)	0.019 (3)	−0.015 (2)	0.016 (3)
C14	0.085 (4)	0.112 (5)	0.082 (4)	0.024 (4)	0.046 (4)	0.006 (4)
C15	0.097 (5)	0.082 (4)	0.074 (4)	−0.046 (4)	0.021 (3)	−0.004 (3)
C16	0.046 (2)	0.057 (3)	0.049 (2)	0.0047 (18)	0.0030 (19)	0.017 (2)
Cl3	0.0657 (7)	0.0632 (8)	0.0793 (8)	−0.0286 (6)	0.0057 (6)	0.0147 (6)
Cl4	0.0472 (6)	0.1082 (11)	0.0649 (7)	0.0060 (7)	0.0215 (5)	0.0002 (8)
Br1	0.0901 (4)	0.0583 (3)	0.0637 (3)	−0.0039 (3)	−0.0277 (3)	−0.0181 (2)
Br2	0.0869 (4)	0.1127 (5)	0.0659 (4)	−0.0004 (4)	0.0151 (3)	0.0420 (3)

Geometric parameters (Å, º) top

C1—C12	1.513 (5)	C8—H8	0.9800
C1—C2	1.524 (5)	C9—C10	1.323 (6)
C1—C8	1.529 (5)	C9—H9	0.9300
C1—C3	1.541 (5)	C10—C16	1.489 (6)
C2—C3	1.502 (6)	C10—C11	1.495 (5)
C2—Cl3	1.763 (5)	C11—C12	1.520 (5)
C2—Cl4	1.765 (4)	C11—Br1	1.975 (4)
C3—C4	1.514 (7)	C11—H11	0.9800
C3—C13	1.531 (7)	C12—H12A	0.9700
C4—C5	1.538 (6)	C12—H12B	0.9700
C4—H4A	0.9700	C13—H13A	0.9600
C4—H4B	0.9700	C13—H13B	0.9600
C5—C6	1.515 (8)	C13—H13C	0.9600
C5—H5A	0.9700	C14—H14A	0.9600
C5—H5B	0.9700	C14—H14B	0.9600
C6—C7	1.552 (7)	C14—H14C	0.9600
C6—H6A	0.9700	C15—H15A	0.9600
C6—H6B	0.9700	C15—H15B	0.9600
C7—C15	1.470 (7)	C15—H15C	0.9600
C7—C14	1.540 (8)	C16—Br2	1.959 (4)
C7—C8	1.596 (5)	C16—H16A	0.9700
C8—C9	1.497 (5)	C16—H16B	0.9700

C12—C1—C2	116.6 (3)	C9—C8—H8	106.2
C12—C1—C8	112.4 (3)	C1—C8—H8	106.2
C2—C1—C8	119.2 (3)	C7—C8—H8	106.2
C12—C1—C3	121.0 (3)	C10—C9—C8	126.8 (3)
C2—C1—C3	58.7 (3)	C10—C9—H9	116.6
C8—C1—C3	118.9 (3)	C8—C9—H9	116.6
C3—C2—C1	61.2 (2)	C9—C10—C16	120.2 (4)
C3—C2—Cl3	121.2 (3)	C9—C10—C11	121.0 (3)
C1—C2—Cl3	120.6 (3)	C16—C10—C11	118.8 (3)
C3—C2—Cl4	119.5 (3)	C10—C11—C12	113.6 (3)
C1—C2—Cl4	119.2 (3)	C10—C11—Br1	110.2 (3)
Cl3—C2—Cl4	108.6 (2)	C12—C11—Br1	107.3 (3)
C2—C3—C4	119.1 (4)	C10—C11—H11	108.5
C2—C3—C13	118.9 (4)	C12—C11—H11	108.5
C4—C3—C13	112.1 (4)	Br1—C11—H11	108.5
C2—C3—C1	60.1 (2)	C1—C12—C11	110.7 (3)
C4—C3—C1	118.4 (4)	C1—C12—H12A	109.5
C13—C3—C1	119.2 (4)	C11—C12—H12A	109.5
C3—C4—C5	112.9 (4)	C1—C12—H12B	109.5
C3—C4—H4A	109.0	C11—C12—H12B	109.5
C5—C4—H4A	109.0	H12A—C12—H12B	108.1
C3—C4—H4B	109.0	C3—C13—H13A	109.5
C5—C4—H4B	109.0	C3—C13—H13B	109.5
H4A—C4—H4B	107.8	H13A—C13—H13B	109.5
C6—C5—C4	111.3 (4)	C3—C13—H13C	109.5
C6—C5—H5A	109.4	H13A—C13—H13C	109.5
C4—C5—H5A	109.4	H13B—C13—H13C	109.5
C6—C5—H5B	109.4	C7—C14—H14A	109.5
C4—C5—H5B	109.4	C7—C14—H14B	109.5
H5A—C5—H5B	108.0	H14A—C14—H14B	109.5
C5—C6—C7	119.2 (5)	C7—C14—H14C	109.5
C5—C6—H6A	107.5	H14A—C14—H14C	109.5
C7—C6—H6A	107.5	H14B—C14—H14C	109.5
C5—C6—H6B	107.5	C7—C15—H15A	109.5
C7—C6—H6B	107.5	C7—C15—H15B	109.5
H6A—C6—H6B	107.0	H15A—C15—H15B	109.5
C15—C7—C14	108.4 (5)	C7—C15—H15C	109.5
C15—C7—C6	111.6 (5)	H15A—C15—H15C	109.5
C14—C7—C6	103.8 (4)	H15B—C15—H15C	109.5
C15—C7—C8	114.9 (4)	C10—C16—Br2	112.2 (3)
C14—C7—C8	107.6 (4)	C10—C16—H16A	109.2
C6—C7—C8	110.0 (4)	Br2—C16—H16A	109.2
C9—C8—C1	109.4 (3)	C10—C16—H16B	109.2
C9—C8—C7	112.0 (3)	Br2—C16—H16B	109.2
C1—C8—C7	116.2 (3)	H16A—C16—H16B	107.9

Experimental details

Crystal data
Chemical formula	C₁₆H₂₂Br₂Cl₂
M_r	445.06
Crystal system, space group	Orthorhombic, P2₁2₁2₁
Temperature (K)	293
a, b, c (Å)	8.2594 (7), 13.0352 (11), 16.6241 (13)
V (Å³)	1789.8 (3)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	4.82
Crystal size (mm)	0.20 × 0.15 × 0.12

Data collection
Diffractometer	Bruker APEXII CCD diffractometer
Absorption correction	Multi-scan SHELXS97 (Sheldrick,2008)
T_min, T_max	0.423, 0.617
No. of measured, independent and observed [I > 2σ(I)] reflections	10693, 3654, 3183
R_int	0.026
(sin θ/λ)_max (Å⁻¹)	0.625

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.038, 0.102, 1.05
No. of reflections	3654
No. of parameters	184
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.55, −0.54
Absolute structure	Flack & Bernardinelli (2000), 614 Friedel pairs
Absolute structure parameter	0.022 (13)

Computer programs: APEX2 (Bruker, 2009), SAINT (Bruker, 2009), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), ORTEP-3 for Windows (Farrugia, 2012), WinGX (Farrugia, 2012).

Acknowledgements

The authors thank the Unit of Support for Technical and Scientific Research (UATRS, CNRST) for the X-ray measurements.

References

Benharref, A., El Karroumi, J., El Ammari, L., Saadi, M. & Berraho, M. (2013). Acta Cryst. E69, o1037–o1038. CSD CrossRef CAS IUCr Journals Google Scholar
Bruker (2009). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Cremer, D. & Pople, J. A. (1975). J. Am. Chem. Soc. 97, 1354–1358. CrossRef CAS Web of Science Google Scholar
Daoubi, M., Duran-Patron, R., Hmamouchi, M., Hernandez-Galan, R., Benharref, A. & Isidro, G. C. (2004). Pest Manag. Sci. 60, 927–932. Web of Science CrossRef PubMed CAS Google Scholar
El Haib, A., Benharref, A., Parres-Maynadie, S., Manoury, E., Urrutigoıty, M. & Gouygou, M. (2011). Tetrahedron Asymmetry, 22, 101–108. Web of Science CrossRef CAS Google Scholar
El Jamili, H., Auhmani, A., Dakir, M., Lassaba, E., Benharref, A., Pierrot, M., Chiaroni, A. & Riche, C. (2002). Tetrahedron Lett. 43, 6645–6648. CAS Google Scholar
Farrugia, L. J. (2012). J. Appl. Cryst. 45, 849–854. Web of Science CrossRef CAS IUCr Journals Google Scholar
Flack, H. D. & Bernardinelli, G. (2000). J. Appl. Cryst. 33, 1143–1148. Web of Science CrossRef CAS IUCr Journals Google Scholar
Oukhrib, A., Benharref, A., Saadi, M., Berraho, M. & El Ammari, L. (2013). Acta Cryst. E69, o521–o522. CSD CrossRef CAS IUCr Journals Google Scholar
Ourhriss, N., Benharref, A., Saadi, M., El Ammari, L. & Berraho, M. (2013). Acta Cryst. E69, o275. CSD CrossRef IUCr Journals Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar

This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.