2,8-Dichloro-6H,12H-5,11-ethano­dibenzo[b,f][1,5]diazo­cine

Faroughi, M.; Try, A.C.; Turner, P.

doi:10.1107/S1600536807062642

organic compounds

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ISSN: 2056-9890

Volume 64| Part 1| January 2008| Page o39

https://doi.org/10.1107/S1600536807062642

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2,8-Dichloro-6H,12H-5,11-ethanodibenzo[b,f][1,5]diazocine

Masoud Faroughi,^a Andrew C. Try ^a ^* and Peter Turner ^b

^aDepartment of Chemistry and Biomolecular Sciences, Building F7B, Macquarie University, NSW 2109, Australia, and ^bCrystal Structure Analysis Facility, School of Chemistry, F11, The University of Sydney, NSW 2006, Australia
^*Correspondence e-mail: andrew.try@mq.edu.au

(Received 23 November 2007; accepted 23 November 2007; online 6 December 2007)

In the molecule of the title compound, C₁₆H₁₄Cl₂N₂, the ethano-strapped 2,8-dichloro analogue of Tröger's base, the dihedral angle between the two benzene rings is 87.01 (3)°.

Related literature

For related literature, see: Tröger (1887 ); Hamada & Mukai (1996 ); Ishida et al. (2005 ). For related structures, see: Spielman (1935 ); Larson & Wilcox (1986 ); Solano et al. (2005 ); Faroughi et al. (2006a ,b ); Faroughi, Try, Klepetko & Turner (2007 ); Faroughi, Try & Turner (2007 ).

Experimental

Crystal data

C₁₆H₁₄Cl₂N₂
M_r = 305.19
Triclinic, $[P \overline 1]$
a = 6.8801 (11) Å
b = 10.1951 (17) Å
c = 10.2466 (16) Å
α = 85.320 (3)°
β = 84.956 (2)°
γ = 76.470 (3)°
V = 694.70 (19) Å³
Z = 2
Mo Kα radiation
μ = 0.46 mm⁻¹
T = 150 (2) K
0.63 × 0.44 × 0.41 mm

Data collection

Bruker SMART 1000 CCD diffractometer
Absorption correction: Gaussian (XPREP; Coppens et al., 1965 ; Siemens, 1995 ) T_min = 0.773, T_max = 0.869
6876 measured reflections
3188 independent reflections
2992 reflections with I > 2σ(I)
R_int = 0.033

Refinement

R[F² > 2σ(F²)] = 0.031
wR(F²) = 0.089
S = 1.06
3188 reflections
181 parameters
H-atom parameters constrained
Δρ_max = 0.34 e Å⁻³
Δρ_min = −0.27 e Å⁻³

Data collection: SMART (Siemens, 1995); cell refinement: SAINT (Siemens, 1995); data reduction: SAINT and XPREP (Siemens, 1995); program(s) used to solve structure: SIR97 (Altomare et al., 1999 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997 ); molecular graphics: Xtal3.6 (Hall et al., 1999 ), ORTEPII (Johnson, 1976 ) and WinGX (Farrugia, 1999 ); software used to prepare material for publication: WinGX.

Supporting information

Crystal structure: contains datablocks global, I. DOI: https://doi.org/10.1107/S1600536807062642/hk2402sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536807062642/hk2402Isup2.hkl

checkCIF report

Comment top

Tröger's base was first prepared in 1887 (Tröger, 1887) and its structure was elucidated until over 30 years latter (Spielman, 1935). The strucural assignment was confirmed by X-ray crystallography (Larson & Wilcox, 1986). Since then large number of related compounds have been reported and the dihedral angle, between the least-squares planes through the aromatic rings, has been measured across a range of simple dibenzo Tröger's base analogues and found to lie between 82° (Solano et al., 2005) and 108° (Faroughi et al., 2006b). A common structural feature in all of these compounds is the methano-strapped diazocine bridge. The conversion of methano-strapped compounds to ethano-strapped analogues of Tröger's base have been reported for 2,8-dimethyl- and 2,8-dimethoxy- (Hamada & Mukai, 1996) as well as 2,8-dibromo- (Ishida et al., 2005; Faroughi, Try, Klepetko & Turner, 2007) substitution patterns. We have previously reported that the dihedral angle in methano-strapped 2,8-dibromo Tröger's base is 94.5° (Faroughi et al., 2006a) whilst the corresponding angle in the ethano-strapped 2,8-dibromo analogue is 86.1° (Faroughi, Try, Klepetko & Turner, 2007). In the present case, the dihedral angle of ethano-strapped 2,8-dichloro Tröger's base (I), whose molecular structure is shown in Fig. 1, was also found to be reduced [87.01 (3)°] in comparison with the methano-strapped analogue, which has a dihedral angle of 95.6° (Faroughi, Try & Turner et al., 2007).

Related literature top

For related literature, see: Tröger (1887); Hamada & Mukai (1996); Ishida et al. (2005). For related structures, see: Spielman (1935); Larson & Wilcox (1986); Solano et al. (2005); Faroughi et al. (2006a,b); Faroughi, Try, Klepetko & Turner (2007); Faroughi, Try & Turner (2007).

Experimental top

The title compound was prepared according to the literature procedure (Hamada & Mukai, 1996) in 72% yield. Single crystals of (I) were produced from slow evaporation of a dichloromethane solution.

Structure description top

For related literature, see: Tröger (1887); Hamada & Mukai (1996); Ishida et al. (2005). For related structures, see: Spielman (1935); Larson & Wilcox (1986); Solano et al. (2005); Faroughi et al. (2006a,b); Faroughi, Try, Klepetko & Turner (2007); Faroughi, Try & Turner (2007).

Computing details top

Data collection: SMART (Siemens, 1995); cell refinement: SAINT (Siemens, 1995); data reduction: SAINT and XPREP (Siemens, 1995); program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: Xtal3.6 (Hall et al., 1999), ORTEPII (Johnson, 1976) and WinGX (Farrugia, 1999); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures top

	Fig. 1. View of (I), showing the atomic numbering scheme. Displacement ellipsoids are shown at the 50% probability level.
	Fig. 2. Synthetic scheme for the synthesis of (I) showing the numbering system used in naming the compound.

2,8-Dichloro-6H,12H-5,11- ethanodibenzo[b,f][1,5]diazocine top

Crystal data top

C₁₆H₁₄Cl₂N₂	Z = 2
M_r = 305.19	F(000) = 316
Triclinic, P1	D_x = 1.459 Mg m⁻³
Hall symbol: -P 1	Melting point = 454–455 K
a = 6.8801 (11) Å	Mo Kα radiation, λ = 0.71073 Å
b = 10.1951 (17) Å	Cell parameters from 925 reflections
c = 10.2466 (16) Å	θ = 3.5–27.9°
α = 85.320 (3)°	µ = 0.46 mm⁻¹
β = 84.956 (2)°	T = 150 K
γ = 76.470 (3)°	Prism, colorless
V = 694.70 (19) Å³	0.63 × 0.44 × 0.41 mm

Data collection top

Bruker SMART 1000 CCD diffractometer	3188 independent reflections
Radiation source: fine-focus sealed tube	2992 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.033
ω scans	θ_max = 28.3°, θ_min = 2.0°
Absorption correction: gaussian (XPREP; Coppens et al., 1965; Siemens, 1995)	h = −8→9
T_min = 0.773, T_max = 0.869	k = −13→13
6876 measured reflections	l = −13→13

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) = 0.089	H-atom parameters constrained
S = 1.06	w = 1/[σ²(F_o²) + (0.051P)² + 0.1729P] where P = (F_o² + 2F_c²)/3
3188 reflections	(Δ/σ)_max = 0.002
181 parameters	Δρ_max = 0.34 e Å⁻³
0 restraints	Δρ_min = −0.27 e Å⁻³

Crystal data top

C₁₆H₁₄Cl₂N₂	γ = 76.470 (3)°
M_r = 305.19	V = 694.70 (19) Å³
Triclinic, P1	Z = 2
a = 6.8801 (11) Å	Mo Kα radiation
b = 10.1951 (17) Å	µ = 0.46 mm⁻¹
c = 10.2466 (16) Å	T = 150 K
α = 85.320 (3)°	0.63 × 0.44 × 0.41 mm
β = 84.956 (2)°

Data collection top

Bruker SMART 1000 CCD diffractometer	3188 independent reflections
Absorption correction: gaussian (XPREP; Coppens et al., 1965; Siemens, 1995)	2992 reflections with I > 2σ(I)
T_min = 0.773, T_max = 0.869	R_int = 0.033
6876 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.031	0 restraints
wR(F²) = 0.089	H-atom parameters constrained
S = 1.06	Δρ_max = 0.34 e Å⁻³
3188 reflections	Δρ_min = −0.27 e Å⁻³
181 parameters

Special details top

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.

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 (Å²) top

	x	y	z	U_iso*/U_eq
Cl1	−0.33151 (5)	0.87520 (3)	1.11085 (3)	0.03317 (10)
Cl2	0.19414 (5)	1.02485 (3)	0.31142 (3)	0.03303 (10)
N1	0.43135 (15)	0.61940 (11)	0.81861 (11)	0.0288 (2)
N2	0.19355 (15)	0.52439 (10)	0.65450 (10)	0.0249 (2)
C1	0.24125 (17)	0.67773 (12)	0.88354 (11)	0.0256 (2)
C2	0.23827 (19)	0.77730 (13)	0.96964 (13)	0.0300 (3)
H2	0.3590	0.8039	0.9806	0.036*
C3	0.0642 (2)	0.83825 (12)	1.03940 (12)	0.0297 (3)
H3	0.0645	0.9057	1.0981	0.036*
C4	−0.11108 (18)	0.79898 (12)	1.02196 (11)	0.0261 (2)
C5	−0.11437 (17)	0.70205 (12)	0.93531 (11)	0.0242 (2)
H5	−0.2366	0.6777	0.9238	0.029*
C6	0.06195 (17)	0.64005 (11)	0.86481 (11)	0.0231 (2)
C7	0.04879 (17)	0.53679 (12)	0.76854 (11)	0.0247 (2)
H7A	0.0654	0.4472	0.8169	0.030*
H7B	−0.0876	0.5605	0.7367	0.030*
C8	0.19502 (17)	0.64895 (11)	0.57911 (11)	0.0229 (2)
C9	0.05736 (18)	0.68840 (12)	0.48295 (11)	0.0250 (2)
H9	−0.0354	0.6346	0.4732	0.030*
C10	0.05307 (18)	0.80449 (12)	0.40135 (11)	0.0267 (2)
H10	−0.0423	0.8310	0.3370	0.032*
C11	0.19158 (18)	0.88103 (12)	0.41608 (11)	0.0256 (2)
C12	0.32586 (18)	0.84588 (12)	0.51236 (12)	0.0265 (2)
H12	0.4170	0.9009	0.5220	0.032*
C13	0.32901 (17)	0.73018 (12)	0.59568 (11)	0.0250 (2)
C14	0.48177 (18)	0.69776 (14)	0.69929 (13)	0.0317 (3)
H14A	0.6103	0.6474	0.6582	0.038*
H14B	0.5042	0.7841	0.7254	0.038*
C15	0.47175 (18)	0.47337 (13)	0.80467 (13)	0.0324 (3)
H15A	0.4103	0.4303	0.8826	0.039*
H15B	0.6183	0.4358	0.8017	0.039*
C16	0.39027 (19)	0.43836 (13)	0.68131 (13)	0.0319 (3)
H16A	0.4863	0.4477	0.6052	0.038*
H16B	0.3797	0.3428	0.6914	0.038*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Cl1	0.03691 (18)	0.03002 (17)	0.03158 (17)	−0.00488 (12)	−0.00344 (12)	−0.00303 (12)
Cl2	0.0492 (2)	0.02418 (16)	0.02644 (16)	−0.01157 (13)	−0.00413 (12)	0.00531 (11)
N1	0.0231 (5)	0.0311 (5)	0.0321 (5)	−0.0078 (4)	−0.0082 (4)	0.0091 (4)
N2	0.0270 (5)	0.0203 (5)	0.0266 (5)	−0.0053 (4)	−0.0019 (4)	0.0024 (4)
C1	0.0256 (5)	0.0257 (6)	0.0264 (5)	−0.0078 (4)	−0.0101 (4)	0.0080 (4)
C2	0.0314 (6)	0.0291 (6)	0.0333 (6)	−0.0125 (5)	−0.0160 (5)	0.0065 (5)
C3	0.0403 (7)	0.0237 (6)	0.0279 (6)	−0.0100 (5)	−0.0145 (5)	0.0035 (4)
C4	0.0316 (6)	0.0228 (5)	0.0231 (5)	−0.0051 (4)	−0.0069 (4)	0.0042 (4)
C5	0.0269 (5)	0.0242 (5)	0.0232 (5)	−0.0094 (4)	−0.0072 (4)	0.0047 (4)
C6	0.0264 (5)	0.0219 (5)	0.0223 (5)	−0.0085 (4)	−0.0075 (4)	0.0055 (4)
C7	0.0261 (5)	0.0239 (5)	0.0258 (5)	−0.0097 (4)	−0.0039 (4)	0.0020 (4)
C8	0.0253 (5)	0.0198 (5)	0.0231 (5)	−0.0048 (4)	−0.0006 (4)	0.0001 (4)
C9	0.0291 (5)	0.0244 (6)	0.0231 (5)	−0.0089 (4)	−0.0026 (4)	−0.0028 (4)
C10	0.0326 (6)	0.0266 (6)	0.0213 (5)	−0.0064 (5)	−0.0058 (4)	−0.0006 (4)
C11	0.0333 (6)	0.0203 (5)	0.0222 (5)	−0.0060 (4)	0.0001 (4)	0.0011 (4)
C12	0.0277 (5)	0.0252 (6)	0.0277 (6)	−0.0096 (4)	−0.0012 (4)	0.0009 (4)
C13	0.0235 (5)	0.0254 (6)	0.0262 (5)	−0.0064 (4)	−0.0033 (4)	0.0019 (4)
C14	0.0240 (5)	0.0366 (7)	0.0358 (7)	−0.0120 (5)	−0.0081 (5)	0.0104 (5)
C15	0.0252 (6)	0.0308 (6)	0.0376 (7)	−0.0019 (5)	−0.0051 (5)	0.0099 (5)
C16	0.0311 (6)	0.0236 (6)	0.0367 (6)	−0.0012 (5)	0.0003 (5)	0.0053 (5)

Geometric parameters (Å, º) top

Cl1—C4	1.7477 (13)	C7—H7B	0.9900
Cl2—C11	1.7471 (12)	C8—C9	1.3968 (16)
N1—C1	1.4334 (16)	C8—C13	1.4043 (16)
N1—C15	1.4657 (17)	C9—C10	1.3882 (17)
N1—C14	1.4659 (16)	C9—H9	0.9500
N2—C8	1.4332 (14)	C10—C11	1.3901 (17)
N2—C7	1.4608 (15)	C10—H10	0.9500
N2—C16	1.4653 (16)	C11—C12	1.3795 (17)
C1—C2	1.3937 (18)	C12—C13	1.3956 (16)
C1—C6	1.4077 (15)	C12—H12	0.9500
C2—C3	1.3802 (19)	C13—C14	1.5223 (16)
C2—H2	0.9500	C14—H14A	0.9900
C3—C4	1.3865 (17)	C14—H14B	0.9900
C3—H3	0.9500	C15—C16	1.5269 (19)
C4—C5	1.3866 (17)	C15—H15A	0.9900
C5—C6	1.3980 (17)	C15—H15B	0.9900
C5—H5	0.9500	C16—H16A	0.9900
C6—C7	1.5230 (16)	C16—H16B	0.9900
C7—H7A	0.9900

C1—N1—C15	115.51 (10)	C10—C9—C8	121.47 (11)
C1—N1—C14	113.66 (10)	C10—C9—H9	119.3
C15—N1—C14	114.24 (11)	C8—C9—H9	119.3
C8—N2—C7	114.43 (9)	C9—C10—C11	118.43 (11)
C8—N2—C16	115.99 (9)	C9—C10—H10	120.8
C7—N2—C16	113.67 (9)	C11—C10—H10	120.8
C2—C1—C6	119.43 (11)	C12—C11—C10	121.14 (11)
C2—C1—N1	116.75 (10)	C12—C11—Cl2	119.53 (9)
C6—C1—N1	123.82 (11)	C10—C11—Cl2	119.33 (9)
C3—C2—C1	121.62 (11)	C11—C12—C13	120.58 (11)
C3—C2—H2	119.2	C11—C12—H12	119.7
C1—C2—H2	119.2	C13—C12—H12	119.7
C2—C3—C4	118.57 (11)	C12—C13—C8	119.04 (10)
C2—C3—H3	120.7	C12—C13—C14	117.56 (10)
C4—C3—H3	120.7	C8—C13—C14	123.39 (10)
C3—C4—C5	121.36 (12)	N1—C14—C13	116.80 (10)
C3—C4—Cl1	118.71 (10)	N1—C14—H14A	108.1
C5—C4—Cl1	119.92 (9)	C13—C14—H14A	108.1
C4—C5—C6	120.10 (10)	N1—C14—H14B	108.1
C4—C5—H5	120.0	C13—C14—H14B	108.1
C6—C5—H5	120.0	H14A—C14—H14B	107.3
C5—C6—C1	118.91 (11)	N1—C15—C16	112.65 (10)
C5—C6—C7	117.90 (10)	N1—C15—H15A	109.1
C1—C6—C7	123.18 (11)	C16—C15—H15A	109.1
N2—C7—C6	116.32 (9)	N1—C15—H15B	109.1
N2—C7—H7A	108.2	C16—C15—H15B	109.1
C6—C7—H7A	108.2	H15A—C15—H15B	107.8
N2—C7—H7B	108.2	N2—C16—C15	112.95 (11)
C6—C7—H7B	108.2	N2—C16—H16A	109.0
H7A—C7—H7B	107.4	C15—C16—H16A	109.0
C9—C8—C13	119.27 (10)	N2—C16—H16B	109.0
C9—C8—N2	117.29 (10)	C15—C16—H16B	109.0
C13—C8—N2	123.43 (10)	H16A—C16—H16B	107.8

C15—N1—C1—C2	140.54 (11)	C16—N2—C8—C13	−39.77 (16)
C14—N1—C1—C2	−84.57 (13)	C13—C8—C9—C10	1.50 (18)
C15—N1—C1—C6	−39.47 (15)	N2—C8—C9—C10	−177.27 (10)
C14—N1—C1—C6	95.42 (14)	C8—C9—C10—C11	0.77 (18)
C6—C1—C2—C3	1.36 (18)	C9—C10—C11—C12	−2.32 (18)
N1—C1—C2—C3	−178.64 (11)	C9—C10—C11—Cl2	178.13 (9)
C1—C2—C3—C4	−0.33 (18)	C10—C11—C12—C13	1.56 (18)
C2—C3—C4—C5	−0.88 (18)	Cl2—C11—C12—C13	−178.90 (9)
C2—C3—C4—Cl1	179.63 (9)	C11—C12—C13—C8	0.77 (18)
C3—C4—C5—C6	1.03 (17)	C11—C12—C13—C14	179.84 (11)
Cl1—C4—C5—C6	−179.48 (8)	C9—C8—C13—C12	−2.26 (17)
C4—C5—C6—C1	0.03 (16)	N2—C8—C13—C12	176.43 (10)
C4—C5—C6—C7	−178.54 (10)	C9—C8—C13—C14	178.73 (11)
C2—C1—C6—C5	−1.19 (17)	N2—C8—C13—C14	−2.57 (18)
N1—C1—C6—C5	178.82 (10)	C1—N1—C14—C13	−54.36 (15)
C2—C1—C6—C7	177.30 (10)	C15—N1—C14—C13	81.12 (14)
N1—C1—C6—C7	−2.70 (17)	C12—C13—C14—N1	153.32 (12)
C8—N2—C7—C6	−54.43 (13)	C8—C13—C14—N1	−27.67 (18)
C16—N2—C7—C6	82.00 (12)	C1—N1—C15—C16	86.66 (13)
C5—C6—C7—N2	150.29 (10)	C14—N1—C15—C16	−47.97 (14)
C1—C6—C7—N2	−28.21 (15)	C8—N2—C16—C15	86.98 (12)
C7—N2—C8—C9	−85.65 (13)	C7—N2—C16—C15	−48.75 (14)
C16—N2—C8—C9	138.96 (11)	N1—C15—C16—N2	−39.74 (14)
C7—N2—C8—C13	95.62 (13)

Experimental details

Crystal data
Chemical formula	C₁₆H₁₄Cl₂N₂
M_r	305.19
Crystal system, space group	Triclinic, P1
Temperature (K)	150
a, b, c (Å)	6.8801 (11), 10.1951 (17), 10.2466 (16)
α, β, γ (°)	85.320 (3), 84.956 (2), 76.470 (3)
V (Å³)	694.70 (19)
Z	2
Radiation type	Mo Kα
µ (mm⁻¹)	0.46
Crystal size (mm)	0.63 × 0.44 × 0.41

Data collection
Diffractometer	Bruker SMART 1000 CCD diffractometer
Absorption correction	Gaussian (XPREP; Coppens et al., 1965; Siemens, 1995)
T_min, T_max	0.773, 0.869
No. of measured, independent and observed [I > 2σ(I)] reflections	6876, 3188, 2992
R_int	0.033
(sin θ/λ)_max (Å⁻¹)	0.666

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.031, 0.089, 1.06
No. of reflections	3188
No. of parameters	181
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.34, −0.27

Computer programs: SMART (Siemens, 1995), SAINT (Siemens, 1995), SAINT and XPREP (Siemens, 1995), SIR97 (Altomare et al., 1999), SHELXL97 (Sheldrick, 1997), Xtal3.6 (Hall et al., 1999), ORTEPII (Johnson, 1976) and WinGX (Farrugia, 1999), WinGX (Farrugia, 1999).

Acknowledgements

The authors thank the Australian Research Council for a Discovery Project grant to ACT (grant No. DP0345180) and Macquarie University for the award of a Macquarie University Research Development grant.

References

Altomare, A., Burla, M. C., Camalli, M., Cascarano, G. L., Giacovazzo, C., Guagliardi, A., Moliterni, A. G. G., Polidori, G. & Spagna, R. (1999). J. Appl. Cryst. 32, 115–119. Web of Science CrossRef CAS IUCr Journals Google Scholar
Coppens, P., Leiserowitz, L. & Rabinovich, D. (1965). Acta Cryst. 18, 1035–1038. CrossRef CAS IUCr Journals Web of Science Google Scholar
Faroughi, M., Try, A. C., Klepetko, J. & Turner, P. (2007). Tetrahedron Lett. 48, 6548–6551. Web of Science CSD CrossRef CAS Google Scholar
Faroughi, M., Try, A. C. & Turner, P. (2006a). Acta Cryst. E62, o3674–o3675. Web of Science CSD CrossRef IUCr Journals Google Scholar
Faroughi, M., Try, A. C. & Turner, P. (2006b). Acta Cryst. E62, o3893–o3894. Web of Science CSD CrossRef IUCr Journals Google Scholar
Faroughi, M., Try, A. C. & Turner, P. (2007). Acta Cryst. E63, o2695. Web of Science CSD CrossRef IUCr Journals Google Scholar
Farrugia, L. J. (1999). J. Appl. Cryst. 32, 837–838. CrossRef CAS IUCr Journals Google Scholar
Hall, S. R., du Boulay, D. J. & Olthof-Hazekamp, R. (1999). Editors. The Xtal3.6 System. University of Western Australia. Google Scholar
Hamada, Y. & Mukai, S. (1996). Tetrahedron Asymmetry, 7, 2671–2674. CrossRef CAS Web of Science Google Scholar
Ishida, Y., Ito, H., Mori, D. & Saigo, K. (2005). Tetrahedron Lett. 46, 109–112. Web of Science CrossRef CAS Google Scholar
Johnson, C. K. (1976). ORTEPII. Report ORNL-5138. Oak Ridge National Laboratory, Tennessee, USA. Google Scholar
Larson, S. B. & Wilcox, C. S. (1986). Acta Cryst. C42, 224–227. CSD CrossRef CAS IUCr Journals Google Scholar
Sheldrick, G. M. (1997). SHELXL97. University of Göttingen, Germany. Google Scholar
Siemens (1995). SMART, SAINT and XPREP. Siemens Analytical X-ray Instruments Inc., Madison, Wisconsin, USA. Google Scholar
Solano, C., Svensson, D., Olomi, Z., Jensen, J., Wendt, O. F. & Wärnmark, K. (2005). Eur. J. Org. Chem. pp. 3510–3517. Web of Science CSD CrossRef Google Scholar
Spielman, M. A. (1935). J. Am. Chem. Soc. 57, 583–585. CrossRef CAS Google Scholar
Tröger, J. (1887). J. Prakt. Chem. 36, 225–245. CrossRef Google Scholar