(1S,3R,8R)-2,2-Di­chloro-3,7,7,10-tetra­methyl­tri­cyclo­[6.4.0.01,3]dodec-9-en-11-one

Ourhriss, N.; Benharref, A.; Oukhrib, A.; Daran, J.-C.; Berraho, M.

doi:10.1107/S1600536813011781

organic compounds

CRYSTALLOGRAPHIC
COMMUNICATIONS

ISSN: 2056-9890

Volume 69| Part 6| June 2013| Page o830

doi:10.1107/S1600536813011781

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(1S,3R,8R)-2,2-Dichloro-3,7,7,10-tetramethyltricyclo[6.4.0.0^1,3]dodec-9-en-11-one

Naja Ourhriss,^a Ahmed Benharref,^a Abdelouahd Oukhrib,^a Jean-Claude Daran ^b 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, and ^bLaboratoire de Chimie de Coordination, 205 route de Narbonne, 31077 Toulouse Cedex 04, France
^*Correspondence e-mail: berraho@uca.ma

(Received 29 April 2013; accepted 30 April 2013; online 4 May 2013)

The title compound, C₁₆H₂₂Cl₂O, 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 additional three-membered ring arising from the reaction of himachalene with dichlorocarbene. The six-membered ring has an envelope conformation, with the C atom belonging to the three-membered ring forming the flap, whereas the seven-membered ring displays a screw-boat conformation; the dihedral angle between the rings (all atoms) is 59.65 (14)°.

Related literature

For background to the essential oil of the Alas cedar (Cedrus atlantica), see: Joseph & Dev (1968 ); Plattier & Teiseire (1974 ). For the reactivity and biological properties of β-himachalene, see: Benharref et al. (2012 ); Chekroun et al. (2000 ); El Jamili et al. (2002 ); Lassaba et al. (1998 ); Dakir et al. (2004 ); Daoubi et al. (2004 ). For conformational analysis, see: Cremer & Pople (1975 ).

Experimental

Crystal data

C₁₆H₂₂Cl₂O
M_r = 301.24
Monoclinic, P 2₁
a = 8.8780 (3) Å
b = 10.3340 (3) Å
c = 8.9230 (3) Å
β = 108.805 (4)°
V = 774.94 (4) Å³
Z = 2
Cu Kα radiation
μ = 3.67 mm⁻¹
T = 180 K
0.30 × 0.25 × 0.21 mm

Data collection

Agilent Xcalibur (Eos, Gemini ultra) diffractometer
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2010 ) T_min = 0.761, T_max = 1.000
2787 measured reflections
1835 independent reflections
1779 reflections with I > 2σ(I)
R_int = 0.027
θ_max = 60.6°

Refinement

R[F² > 2σ(F²)] = 0.028
wR(F²) = 0.065
S = 1.03
1835 reflections
176 parameters
1 restraint
H-atom parameters constrained
Δρ_max = 0.16 e Å⁻³
Δρ_min = −0.17 e Å⁻³
Absolute structure: Flack & Bernardinelli (2000 ), 614 Friedel pairs
Flack parameter: 0.014 (15)

Data collection: CrysAlis PRO (Agilent, 2010); cell refinement: CrysAlis PRO; data reduction: CrysAlis PRO; 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 ) and PLATON (Spek, 2009 ); software used to prepare material for publication: WinGX (Farrugia, 2012).

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536813011781/tk5222sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536813011781/tk5222Isup2.hkl

Supporting information file. DOI: 10.1107/S1600536813011781/tk5222Isup3.cml

checkCIF report

Comment top

The essential oil of the Alas cedar (Cedrus atlantica) consist mainly (50%) of a bicyclic hydrocarbon called essential oil of the Alas cedar (Cedrus atlantica) consist mainly (50%) of a bicyclic hydrocarbon called (Joseph & Dev, 1968; Plattier & Teiseire, 1974). The reactivity of this sesquiterpene and its derivatives has been studied extensively by our team in order to prepare new products having biological proprieties (Lassaba et al., 1998; Chekroun et al., 2000; El Jamili et al., 2002; Dakir et al., 2004; Benharref et al. 2012). Indeed, these compounds were tested, using the food poisoning technique, for their potential antifungal activity against phytopathogen Botrytis cinerea (Daoubi et al., 2004). We present here the crystal structure of the title compound, (1S,3R,8R)-2,2-dichloro-3,7,7,10-tetramethyltricyclo [6.4.0.0¹,³]dodec-9-en-10-one. The molecule is built up from two fused six-and seven- membered rings and an additional three-membered ring from the reaction with the carbene (Fig. 1). The six-membered ring has an envelope conformation, as indicated by the total puckering amplitude QT = 0.453 (3) Å and spherical polar angle θ = 123.4 (4)° with ϕ = 170.0 (4)°, whereas the seven-membered ring display a boat conformation with QT = 1.1545 (3) Å, θ = 87.74 (2)°, ϕ2 = -48.13 (14)° and ϕ3 = -134.45 (4)° (Cremer & Pople, 1975). Owing to the presence of Cl atoms, the absolute configuration could be fully confirmed, by refining the Flack parameter (Flack & Bernardinelli, 2000) as C1(S), C3(R) and C8(R).

Related literature top

For background to the essential oil of the Alas cedar (Cedrus atlantica), see: Joseph & Dev (1968); Plattier & Teiseire (1974). For the reactivity and biological properties of β-himachalene, see: Benharref et al. (2012); Chekroun et al. (2000); El Jamili et al. (2002); Lassaba et al. (1998); Dakir et al. (2004); Daoubi et al. (2004). For conformational analysis, see: Cremer & Pople (1975).

Experimental top

In a reactor containing a solution of (1S, 3R, 8R)-2,2- dichloro-3,7,7,10 tetramethyltricyclo [6.4.0.0¹,³] dodec-9-ene (1 g, 3.48 mmol) (El Jamili et al., 2002) in 50 ml tetrahydrofuran and water (THF/H₂O) (4:1) cooled to 273 K and kept in the dark, was added in small portions 1.23 g (6.96 mmol) of N-bromosccinimide (NBS). The reaction mixture was left stirring for 1 h, after which 20 ml of a saturated solution of NaHCO₃ was added. Subsequently, the extraction was performed three times with diethyl ether (3x 20 ml). The organic extracts were dried over Na₂SO₄, filtered, concentrated, and chromatographed. The title compound was obtained with a yield of 80% and was recrystallized from its hexane solution.

Computing details top

Data collection: CrysAlis PRO (Agilent, 2010); cell refinement: CrysAlis PRO (Agilent, 2010); data reduction: CrysAlis PRO (Agilent, 2010); 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) and PLATON (Spek, 2009); 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)-2,2-Dichloro-3,7,7,10-tetramethyltricyclo[6.4.0.0^1,3]dodec-9-en-11-one top

Crystal data top

C₁₆H₂₂Cl₂O	F(000) = 320
M_r = 301.24	D_x = 1.291 Mg m⁻³
Monoclinic, P2₁	Cu Kα radiation, λ = 1.5418 Å
Hall symbol: P 2yb	Cell parameters from 1955 reflections
a = 8.8780 (3) Å	θ = 4.3–60.5°
b = 10.3340 (3) Å	µ = 3.67 mm⁻¹
c = 8.9230 (3) Å	T = 180 K
β = 108.805 (4)°	Block, colourless
V = 774.94 (4) Å³	0.30 × 0.25 × 0.21 mm
Z = 2

Data collection top

Agilent Xcalibur (Eos, Gemini ultra) diffractometer	1835 independent reflections
Radiation source: Enhance Ultra (Cu) X-ray Source	1779 reflections with I > 2σ(I)
Mirror monochromator	R_int = 0.027
Detector resolution: 16.1978 pixels mm^-1	θ_max = 60.6°, θ_min = 5.2°
ω scans	h = −9→8
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2010)	k = −11→11
T_min = 0.761, T_max = 1.000	l = −8→10
2787 measured reflections

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)] = 0.028	H-atom parameters constrained
wR(F²) = 0.065	w = 1/[σ²(F_o²) + (0.0268P)²] where P = (F_o² + 2F_c²)/3
S = 1.03	(Δ/σ)_max < 0.001
1835 reflections	Δρ_max = 0.16 e Å⁻³
176 parameters	Δρ_min = −0.17 e Å⁻³
1 restraint	Absolute structure: Flack & Bernardinelli (2000), 614 Friedel pairs
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: 0.014 (15)

Crystal data top

C₁₆H₂₂Cl₂O	V = 774.94 (4) Å³
M_r = 301.24	Z = 2
Monoclinic, P2₁	Cu Kα radiation
a = 8.8780 (3) Å	µ = 3.67 mm⁻¹
b = 10.3340 (3) Å	T = 180 K
c = 8.9230 (3) Å	0.30 × 0.25 × 0.21 mm
β = 108.805 (4)°

Data collection top

Agilent Xcalibur (Eos, Gemini ultra) diffractometer	1835 independent reflections
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2010)	1779 reflections with I > 2σ(I)
T_min = 0.761, T_max = 1.000	R_int = 0.027
2787 measured reflections	θ_max = 60.6°

Refinement top

R[F² > 2σ(F²)] = 0.028	H-atom parameters constrained
wR(F²) = 0.065	Δρ_max = 0.16 e Å⁻³
S = 1.03	Δρ_min = −0.17 e Å⁻³
1835 reflections	Absolute structure: Flack & Bernardinelli (2000), 614 Friedel pairs
176 parameters	Absolute structure parameter: 0.014 (15)
1 restraint

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
Cl1	0.37702 (8)	0.87301 (6)	0.63481 (9)	0.04024 (19)
Cl2	0.53172 (8)	0.67535 (7)	0.51438 (9)	0.0422 (2)
O1	0.7317 (2)	0.4592 (2)	0.9131 (3)	0.0472 (6)
C1	0.3527 (3)	0.6081 (2)	0.7144 (3)	0.0230 (6)
C2	0.3817 (3)	0.7052 (2)	0.6004 (3)	0.0278 (6)
C3	0.2321 (3)	0.6249 (2)	0.5493 (3)	0.0280 (6)
C4	0.0763 (3)	0.6914 (3)	0.5429 (3)	0.0367 (7)
H4A	0.0196	0.7190	0.4329	0.044*
H4B	0.1000	0.7696	0.6105	0.044*
C5	−0.0311 (3)	0.6006 (3)	0.5995 (4)	0.0417 (8)
H5A	−0.1098	0.6536	0.6294	0.050*
H5B	−0.0906	0.5446	0.5100	0.050*
C6	0.0567 (3)	0.5144 (3)	0.7398 (3)	0.0366 (7)
H6A	0.1202	0.4510	0.7025	0.044*
H6B	−0.0241	0.4650	0.7708	0.044*
C7	0.1685 (3)	0.5800 (3)	0.8897 (3)	0.0310 (6)
C8	0.3075 (3)	0.6569 (3)	0.8553 (3)	0.0249 (6)
H8	0.2677	0.7473	0.8285	0.030*
C9	0.4529 (3)	0.6672 (3)	0.9982 (3)	0.0276 (6)
H9	0.4453	0.7195	1.0830	0.033*
C10	0.5923 (3)	0.6092 (3)	1.0171 (3)	0.0289 (7)
C11	0.6079 (3)	0.5170 (3)	0.8973 (3)	0.0289 (6)
C12	0.4618 (3)	0.4911 (2)	0.7555 (3)	0.0276 (6)
H12A	0.4028	0.4166	0.7788	0.033*
H12B	0.4953	0.4681	0.6633	0.033*
C13	0.2113 (4)	0.5220 (3)	0.4243 (3)	0.0410 (7)
H13A	0.1623	0.5602	0.3193	0.061*
H13B	0.1426	0.4530	0.4411	0.061*
H13C	0.3154	0.4858	0.4313	0.061*
C14	0.0742 (4)	0.6748 (4)	0.9559 (4)	0.0483 (8)
H14A	0.0328	0.7447	0.8794	0.072*
H14B	0.1439	0.7114	1.0555	0.072*
H14C	−0.0145	0.6294	0.9753	0.072*
C15	0.2324 (4)	0.4722 (3)	1.0132 (3)	0.0422 (8)
H15A	0.3011	0.5103	1.1123	0.063*
H15B	0.2937	0.4101	0.9733	0.063*
H15C	0.1429	0.4277	1.0326	0.063*
C16	0.7361 (3)	0.6288 (3)	1.1612 (4)	0.0395 (8)
H16A	0.8121	0.6856	1.1345	0.059*
H16B	0.7863	0.5450	1.1974	0.059*
H16C	0.7034	0.6686	1.2456	0.059*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Cl1	0.0401 (4)	0.0234 (3)	0.0606 (5)	0.0026 (3)	0.0209 (3)	0.0072 (3)
Cl2	0.0418 (4)	0.0447 (4)	0.0518 (4)	0.0023 (3)	0.0313 (3)	0.0049 (4)
O1	0.0303 (11)	0.0442 (12)	0.0622 (14)	0.0111 (10)	0.0081 (9)	0.0002 (11)
C1	0.0221 (13)	0.0210 (12)	0.0259 (15)	0.0004 (10)	0.0077 (10)	−0.0016 (11)
C2	0.0249 (14)	0.0268 (14)	0.0358 (16)	0.0033 (10)	0.0153 (11)	0.0027 (12)
C3	0.0240 (14)	0.0314 (15)	0.0292 (15)	0.0012 (11)	0.0093 (11)	0.0024 (11)
C4	0.0246 (15)	0.0439 (17)	0.0376 (17)	0.0060 (12)	0.0046 (11)	0.0013 (14)
C5	0.0207 (14)	0.0578 (19)	0.0425 (18)	−0.0052 (13)	0.0044 (12)	−0.0043 (16)
C6	0.0323 (16)	0.0418 (16)	0.0368 (17)	−0.0130 (13)	0.0126 (12)	−0.0085 (13)
C7	0.0290 (15)	0.0355 (15)	0.0319 (16)	−0.0079 (12)	0.0146 (11)	−0.0076 (13)
C8	0.0224 (13)	0.0252 (14)	0.0273 (14)	0.0002 (11)	0.0084 (10)	−0.0021 (13)
C9	0.0299 (15)	0.0271 (13)	0.0277 (14)	−0.0078 (12)	0.0119 (10)	−0.0036 (13)
C10	0.0274 (16)	0.0276 (14)	0.0301 (16)	−0.0066 (12)	0.0073 (11)	0.0058 (12)
C11	0.0249 (15)	0.0258 (13)	0.0362 (16)	0.0015 (11)	0.0100 (11)	0.0087 (12)
C12	0.0279 (14)	0.0232 (13)	0.0333 (15)	0.0039 (11)	0.0121 (11)	−0.0018 (12)
C13	0.0425 (17)	0.0523 (18)	0.0275 (16)	−0.0021 (14)	0.0105 (13)	−0.0078 (14)
C14	0.0409 (17)	0.0547 (19)	0.061 (2)	−0.0082 (16)	0.0327 (15)	−0.0181 (18)
C15	0.0506 (19)	0.0452 (18)	0.0344 (17)	−0.0140 (15)	0.0189 (13)	0.0004 (15)
C16	0.0299 (16)	0.0473 (19)	0.0361 (17)	−0.0025 (12)	0.0033 (12)	0.0105 (14)

Geometric parameters (Å, º) top

Cl1—C2	1.764 (3)	C8—C9	1.497 (3)
Cl2—C2	1.766 (3)	C8—H8	1.0000
O1—C11	1.218 (3)	C9—C10	1.336 (4)
C1—C2	1.509 (4)	C9—H9	0.9500
C1—C12	1.519 (3)	C10—C11	1.472 (4)
C1—C8	1.523 (4)	C10—C16	1.505 (4)
C1—C3	1.526 (3)	C11—C12	1.516 (4)
C2—C3	1.506 (4)	C12—H12A	0.9900
C3—C13	1.509 (4)	C12—H12B	0.9900
C3—C4	1.529 (4)	C13—H13A	0.9800
C4—C5	1.534 (4)	C13—H13B	0.9800
C4—H4A	0.9900	C13—H13C	0.9800
C4—H4B	0.9900	C14—H14A	0.9800
C5—C6	1.529 (4)	C14—H14B	0.9800
C5—H5A	0.9900	C14—H14C	0.9800
C5—H5B	0.9900	C15—H15A	0.9800
C6—C7	1.543 (4)	C15—H15B	0.9800
C6—H6A	0.9900	C15—H15C	0.9800
C6—H6B	0.9900	C16—H16A	0.9800
C7—C14	1.526 (4)	C16—H16B	0.9800
C7—C15	1.541 (4)	C16—H16C	0.9800
C7—C8	1.579 (4)

C2—C1—C12	117.2 (2)	C1—C8—C7	115.1 (2)
C2—C1—C8	119.0 (2)	C9—C8—H8	106.2
C12—C1—C8	112.4 (2)	C1—C8—H8	106.2
C2—C1—C3	59.49 (16)	C7—C8—H8	106.2
C12—C1—C3	121.2 (2)	C10—C9—C8	125.8 (2)
C8—C1—C3	118.0 (2)	C10—C9—H9	117.1
C3—C2—C1	60.82 (17)	C8—C9—H9	117.1
C3—C2—Cl1	121.74 (18)	C9—C10—C11	119.9 (2)
C1—C2—Cl1	121.15 (19)	C9—C10—C16	122.9 (3)
C3—C2—Cl2	119.2 (2)	C11—C10—C16	117.1 (2)
C1—C2—Cl2	119.59 (18)	O1—C11—C10	121.7 (2)
Cl1—C2—Cl2	108.11 (14)	O1—C11—C12	120.5 (2)
C2—C3—C13	119.9 (2)	C10—C11—C12	117.7 (2)
C2—C3—C1	59.68 (17)	C11—C12—C1	111.6 (2)
C13—C3—C1	120.9 (2)	C11—C12—H12A	109.3
C2—C3—C4	117.6 (2)	C1—C12—H12A	109.3
C13—C3—C4	113.3 (2)	C11—C12—H12B	109.3
C1—C3—C4	115.6 (2)	C1—C12—H12B	109.3
C3—C4—C5	111.3 (2)	H12A—C12—H12B	108.0
C3—C4—H4A	109.4	C3—C13—H13A	109.5
C5—C4—H4A	109.4	C3—C13—H13B	109.5
C3—C4—H4B	109.4	H13A—C13—H13B	109.5
C5—C4—H4B	109.4	C3—C13—H13C	109.5
H4A—C4—H4B	108.0	H13A—C13—H13C	109.5
C6—C5—C4	114.8 (2)	H13B—C13—H13C	109.5
C6—C5—H5A	108.6	C7—C14—H14A	109.5
C4—C5—H5A	108.6	C7—C14—H14B	109.5
C6—C5—H5B	108.6	H14A—C14—H14B	109.5
C4—C5—H5B	108.6	C7—C14—H14C	109.5
H5A—C5—H5B	107.6	H14A—C14—H14C	109.5
C5—C6—C7	118.0 (3)	H14B—C14—H14C	109.5
C5—C6—H6A	107.8	C7—C15—H15A	109.5
C7—C6—H6A	107.8	C7—C15—H15B	109.5
C5—C6—H6B	107.8	H15A—C15—H15B	109.5
C7—C6—H6B	107.8	C7—C15—H15C	109.5
H6A—C6—H6B	107.1	H15A—C15—H15C	109.5
C14—C7—C15	108.0 (2)	H15B—C15—H15C	109.5
C14—C7—C6	109.7 (2)	C10—C16—H16A	109.5
C15—C7—C6	106.7 (2)	C10—C16—H16B	109.5
C14—C7—C8	108.2 (2)	H16A—C16—H16B	109.5
C15—C7—C8	111.9 (2)	C10—C16—H16C	109.5
C6—C7—C8	112.2 (2)	H16A—C16—H16C	109.5
C9—C8—C1	110.0 (2)	H16B—C16—H16C	109.5
C9—C8—C7	112.5 (2)

Experimental details

Crystal data
Chemical formula	C₁₆H₂₂Cl₂O
M_r	301.24
Crystal system, space group	Monoclinic, P2₁
Temperature (K)	180
a, b, c (Å)	8.8780 (3), 10.3340 (3), 8.9230 (3)
β (°)	108.805 (4)
V (Å³)	774.94 (4)
Z	2
Radiation type	Cu Kα
µ (mm⁻¹)	3.67
Crystal size (mm)	0.30 × 0.25 × 0.21

Data collection
Diffractometer	Agilent Xcalibur (Eos, Gemini ultra) diffractometer
Absorption correction	Multi-scan (CrysAlis PRO; Agilent, 2010)
T_min, T_max	0.761, 1.000
No. of measured, independent and observed [I > 2σ(I)] reflections	2787, 1835, 1779
R_int	0.027
θ_max (°)	60.6
(sin θ/λ)_max (Å⁻¹)	0.565

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.028, 0.065, 1.03
No. of reflections	1835
No. of parameters	176
No. of restraints	1
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.16, −0.17
Absolute structure	Flack & Bernardinelli (2000), 614 Friedel pairs
Absolute structure parameter	0.014 (15)

Computer programs: CrysAlis PRO (Agilent, 2010), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), ORTEP-3 for Windows (Farrugia, 2012) and PLATON (Spek, 2009), WinGX (Farrugia, 2012).

References

Agilent (2010). CrysAlis PRO . Agilent Technologies Ltd, Yarnton, England. Google Scholar
Benharref, A., El Ammari, L., Lassaba, E., Ourhriss, N. & Berraho, M. (2012). Acta Cryst. E68, o2502. CSD CrossRef IUCr Journals Google Scholar
Chekroun, A., Jarid, A., Benharref, A. & Boutalib, A. (2000). J. Org. Chem. 65, 4431–4434. Web of Science CrossRef PubMed CAS Google Scholar
Cremer, D. & Pople, J. A. (1975). J. Am. Chem. Soc. 97, 1354–1358. CrossRef CAS Web of Science Google Scholar
Dakir, M., Auhmani, A., Ait Itto, M. Y., Mazoir, N., Akssira, M., Pierrot, M. & Benharref, A. (2004). Synth. Commun. 34, 2001–2008. Web of Science CrossRef CAS 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 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
Joseph, T. C. & Dev, S. (1968). Tetrahedron, 24, 3841–3859. CrossRef CAS Web of Science Google Scholar
Lassaba, E., Eljamili, H., Chekroun, A., Benharref, A., Chiaroni, A., Riche, C. & Lavergne, J.-P. (1998). Synth. Commun. 28, 2641–2651. Web of Science CrossRef CAS Google Scholar
Plattier, M. & Teiseire, P. (1974). Recherche, 19, 131–144. CAS Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Spek, A. L. (2009). Acta Cryst. D65, 148–155. Web of Science CrossRef CAS IUCr Journals Google Scholar

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