(S,Z)-1-Chloro-3-[(3,4,5-trimeth­oxy­benzyl­idene)amino]­propan-2-ol

Ren, Y.; Qian, S.; Hai, L.; Fan, W.; Wu, Y.

doi:10.1107/S1600536810053420

organic compounds

CRYSTALLOGRAPHIC
COMMUNICATIONS

ISSN: 2056-9890

Volume 67| Part 2| February 2011| Page o245

doi:10.1107/S1600536810053420

Open

access

(S,Z)-1-Chloro-3-[(3,4,5-trimethoxybenzylidene)amino]propan-2-ol

Yun Ren,^a Shan Qian,^b Li Hai,^a Wei Fan ^a and Yong Wu ^a ^*

^aKey Laboratory of Drug Targeting of the Education Ministry, West China School of Pharmacy, Sichuan University, Chengdu 610041, People's Republic of China, and ^bBioengineering College, Xihua University, Chengdu 610039, People's Republic of China
^*Correspondence e-mail: wyong@scu.edu.cn

(Received 8 November 2010; accepted 20 December 2010; online 8 January 2011)

In the title compound, C₁₃H₁₈ClNO₄, the two methoxy groups at the meta positions of the attached benzene ring are close to being coplanar with the ring [the methoxy C atoms deviate by 0.267 (7) and 0.059 (7) Å], whereas the third methoxy group at the para position is not coplanar with the benzene ring [methoxy C atom deviates by 1.100 (6) Å]. In the crystal, molecules are linked into a chain along the a axis by O—H⋯N hydrogen bonds.

Related literature

The title compound is an intermediate for the synthesis of linezolid [systematic name (S)-N{3-[3-fluoro-4-(morpholin-4-yl)phenyl]-2-oxo-1,3-oxazolidin-5-yl}methyl)acetamide], which is currently used in the treatment of serious multi-drug resistant Gram-positive bacterial infections caused by strains of staphylococci, streptococci and enterococci, see: Brickner et al. (1996 ); Perrault et al. (2002 ). For synthetic procedures, see: Imbordino et al. (2007 ); Zhao et al. (2006 ).

Experimental

Crystal data

C₁₃H₁₈ClNO₄
M_r = 287.73
Orthorhombic, P 2₁ 2₁ 2₁
a = 6.5332 (12) Å
b = 8.888 (2) Å
c = 25.29 (3) Å
V = 1468.7 (16) Å³
Z = 4
Mo Kα radiation
μ = 0.27 mm⁻¹
T = 296 K
0.32 × 0.28 × 0.20 mm

Data collection

Xcalibur, Eos diffractometer
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction 2009 $[Oxford Diffraction (2009). CrysAlis PRO. Oxford Diffraction Ltd, Yarnton, Oxfordshire, England.]$ ) T_min = 0.760, T_max = 1.0
3967 measured reflections
2695 independent reflections
1599 reflections with I > 2σ(I)
R_int = 0.045

Refinement

R[F² > 2σ(F²)] = 0.051
wR(F²) = 0.126
S = 1.06
2695 reflections
176 parameters
H-atom parameters constrained
Δρ_max = 0.32 e Å⁻³
Δρ_min = −0.21 e Å⁻³
Absolute structure: Flack (1983 ), 931 Friedel pairs
Flack parameter: 0.18 (13)

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1—H1⋯N1ⁱ	0.82	2.08	2.870 (4)	162
Symmetry code: (i) $[x+{\script{1\over 2}}, -y+{\script{3\over 2}}, -z+1]$ .

Data collection: CrysAlis PRO (Oxford Diffraction, 2009 $[Oxford Diffraction (2009). CrysAlis PRO. Oxford Diffraction Ltd, Yarnton, Oxfordshire, England.]$ ); 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: OLEX2 (Dolomanov et al., 2009 ); software used to prepare material for publication: OLEX2.

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536810053420/rn2076sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536810053420/rn2076Isup2.hkl

checkCIF report

Comment top

The optically active S,Z-1-chloro-3-(3,4,5-trimethoxybenzylideneamino) propan-2-ol is a key intermediate for synthesizing Linezolid. Linezolid is a potent, synthetic oxazolidinone, which is currently used in the treatment of serious multi-drug resistant Gram-positive bacterial infections caused by strains of staphylococci, streptococci, and enterococci (Brickner et al., 1996; Perrault et al., 2002). Our interests in synthesizing Linezolid prompted us to develop an efficient methodology for synthesizing S,Z-1-chloro-3-(3,4,5-trimethoxybenzylideneamino)propan-2-ol. In our synthetic work, we obtained the title compound, whose spectral data corresponds with that reported in the literature (Imbordino et al., 2007; Zhao et al., 2006). Its crystal structure is reported here. The two methoxy groups at the meta positions are approximately coplanar with the attached benzene ring, and the C(methoxy) atoms, C11 and C13, are -0.2672 (65) and -0.0588 (73) Å from the plane of benzene ring. Whereas the third methoxy group at the para position is not coplanar with the ring, and the distance of the C(methoxy) atom, C12, is -1.1003 (64) Å. An intermolecular O—H···N hydrogen bond is observed. The molecules are linked into a chain along the a axis by O—H···N hydrogen bonds.

Related literature top

The title compound is an intermediate for the synthesis of linezolid [systematic name (S)-N{3-[3-fluoro-4-(morpholin-4-yl)phenyl]-2-oxo-1,3-oxazolidin-5-yl}methyl)acetamide], which is currently used in the treatment of serious multi-drug resistant Gram-positive bacterial infections caused by strains of staphylococci, streptococci and enterococci, see: Brickner et al. (1996); Perrault et al. (2002). For synthetic procedures, see: Imbordino et al. (2007); Zhao et al. (2006).

Experimental top

To a stirred solution of 3,4,5-trimethoxybenzaldehyde (20.0 g,102 mmol) in 200 ml of methyl tert-butyl ether at room temperature was added concentrated ammonia water (12 ml,161 mmol). After 1 h, to this stirred solution at room temperature was added, dropwise over 20 min, the solution of S-2-(chloromethyl)oxirane (8 ml, 102 mmol) in 200 ml of methyl tert-butyl ether. After 24 h, the organic layer was separated and dried (MgSO₄) and then concentrated under reduced pressure. The residue is dispersed in methyl tert-butyl ether, and left to crystallize 17.3 g (yield 58.8%) of S,Z-1-chloro-3-(3,4,5-trimethoxybenzylideneamino)propan-2-ol. Colourless crystals suitable for X-ray analysis were obtained by slow evaporation in methanol at room temperature.

Computing details top

Data collection: CrysAlis PRO (Oxford Diffraction, 2009); cell refinement: CrysAlis PRO (Oxford Diffraction, 2009); data reduction: CrysAlis PRO (Oxford Diffraction, 2009); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: OLEX2 (Dolomanov et al., 2009); software used to prepare material for publication: OLEX2 (Dolomanov et al., 2009).

Figures top

	Fig. 1. The molecular structure of the title compound, with displacement ellipsoids drawn at the 50% probability level.
	Fig. 2. A packing diagram for the title compound.

(S,Z)-1-Chloro-3-[(3,4,5-trimethoxybenzylidene)amino]propan-2-ol top

Crystal data top

C₁₃H₁₈ClNO₄	F(000) = 608
M_r = 287.73	D_x = 1.301 Mg m⁻³
Orthorhombic, P2₁2₁2₁	Mo Kα radiation, λ = 0.7107 Å
Hall symbol: P 2ac 2ab	Cell parameters from 699 reflections
a = 6.5332 (12) Å	θ = 3.1–29.2°
b = 8.888 (2) Å	µ = 0.27 mm⁻¹
c = 25.29 (3) Å	T = 296 K
V = 1468.7 (16) Å³	Block, colourless
Z = 4	0.32 × 0.28 × 0.20 mm

Data collection top

Xcalibur, Eos diffractometer	2695 independent reflections
Radiation source: Enhance (Mo) X-ray Source	1599 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.045
Detector resolution: 16.0874 pixels mm^-1	θ_max = 26.4°, θ_min = 3.2°
ω scans	h = −8→8
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction 2009)	k = −11→6
T_min = 0.760, T_max = 1.0	l = −20→31
3967 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)] = 0.051	H-atom parameters constrained
wR(F²) = 0.126	w = 1/[σ²(F_o²) + (0.0534P)²] where P = (F_o² + 2F_c²)/3
S = 1.06	(Δ/σ)_max < 0.001
2695 reflections	Δρ_max = 0.32 e Å⁻³
176 parameters	Δρ_min = −0.21 e Å⁻³
0 restraints	Absolute structure: Flack (1983), 931 Friedel pairs
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: 0.18 (13)

Crystal data top

C₁₃H₁₈ClNO₄	V = 1468.7 (16) Å³
M_r = 287.73	Z = 4
Orthorhombic, P2₁2₁2₁	Mo Kα radiation
a = 6.5332 (12) Å	µ = 0.27 mm⁻¹
b = 8.888 (2) Å	T = 296 K
c = 25.29 (3) Å	0.32 × 0.28 × 0.20 mm

Data collection top

Xcalibur, Eos diffractometer	2695 independent reflections
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction 2009)	1599 reflections with I > 2σ(I)
T_min = 0.760, T_max = 1.0	R_int = 0.045
3967 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.051	H-atom parameters constrained
wR(F²) = 0.126	Δρ_max = 0.32 e Å⁻³
S = 1.06	Δρ_min = −0.21 e Å⁻³
2695 reflections	Absolute structure: Flack (1983), 931 Friedel pairs
176 parameters	Absolute structure parameter: 0.18 (13)
0 restraints

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	1.17509 (19)	0.37018 (14)	0.54369 (7)	0.1140 (6)
O1	0.8309 (4)	0.7058 (3)	0.49115 (10)	0.0664 (7)
H1	0.9264	0.7436	0.4749	0.100*
O4	0.0299 (4)	0.9974 (3)	0.65900 (10)	0.0669 (8)
O2	0.3609 (4)	0.7987 (3)	0.80796 (10)	0.0644 (7)
O3	0.0912 (4)	0.9855 (3)	0.76403 (10)	0.0617 (7)
N1	0.5915 (4)	0.6334 (3)	0.58064 (11)	0.0465 (7)
C1	1.0430 (6)	0.4919 (4)	0.49923 (16)	0.0734 (12)
H1B	1.1417	0.5473	0.4782	0.088*
H1A	0.9599	0.4322	0.4754	0.088*
C2	0.9080 (5)	0.6012 (4)	0.52862 (13)	0.0488 (8)
H2	0.9893	0.6546	0.5553	0.059*
C3	0.7283 (5)	0.5258 (4)	0.55492 (15)	0.0522 (9)
H3A	0.6519	0.4696	0.5286	0.063*
H3B	0.7783	0.4549	0.5811	0.063*
C4	0.5835 (5)	0.6308 (4)	0.63124 (14)	0.0488 (9)
H4	0.6702	0.5640	0.6485	0.059*
C5	0.4496 (5)	0.7237 (3)	0.66425 (13)	0.0395 (8)
C6	0.4721 (5)	0.7140 (4)	0.71966 (13)	0.0484 (9)
H6	0.5707	0.6503	0.7339	0.058*
C7	0.3478 (5)	0.7990 (4)	0.75334 (14)	0.0472 (9)
C8	0.2026 (5)	0.8932 (3)	0.73163 (14)	0.0465 (8)
C9	0.1786 (5)	0.9004 (4)	0.67608 (14)	0.0466 (8)
C10	0.3006 (5)	0.8172 (4)	0.64293 (14)	0.0467 (9)
H10	0.2835	0.8234	0.6065	0.056*
C11	0.4771 (6)	0.6841 (5)	0.83311 (14)	0.0685 (11)
H11C	0.4668	0.6952	0.8708	0.103*
H11B	0.6179	0.6924	0.8226	0.103*
H11A	0.4251	0.5874	0.8229	0.103*
C12	−0.0824 (6)	0.9189 (5)	0.78748 (19)	0.0875 (15)
H12C	−0.1499	0.9913	0.8096	0.131*
H12B	−0.0407	0.8342	0.8084	0.131*
H12A	−0.1748	0.8859	0.7603	0.131*
C13	−0.0084 (8)	1.0060 (6)	0.60329 (18)	0.0896 (15)
H13C	−0.1008	1.0875	0.5962	0.134*
H13A	−0.0682	0.9133	0.5914	0.134*
H13B	0.1181	1.0230	0.5849	0.134*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Cl1	0.0817 (7)	0.0840 (8)	0.1764 (16)	0.0268 (7)	0.0172 (9)	0.0122 (9)
O1	0.0611 (14)	0.0825 (17)	0.0555 (17)	0.0065 (15)	0.0092 (14)	0.0266 (15)
O4	0.0658 (15)	0.0730 (18)	0.0620 (19)	0.0251 (14)	−0.0078 (15)	0.0007 (15)
O2	0.0800 (18)	0.0735 (16)	0.0397 (16)	0.0194 (15)	−0.0047 (14)	−0.0117 (13)
O3	0.0610 (15)	0.0594 (15)	0.0647 (17)	0.0101 (14)	0.0073 (14)	−0.0150 (13)
N1	0.0467 (14)	0.0528 (16)	0.0401 (18)	0.0021 (15)	0.0038 (14)	0.0074 (14)
C1	0.067 (2)	0.070 (3)	0.083 (3)	−0.005 (2)	0.023 (2)	−0.007 (2)
C2	0.0478 (17)	0.057 (2)	0.042 (2)	−0.0037 (17)	0.0064 (17)	−0.0005 (18)
C3	0.055 (2)	0.055 (2)	0.046 (2)	−0.0042 (18)	0.0125 (18)	0.0002 (18)
C4	0.0481 (18)	0.051 (2)	0.047 (2)	0.0039 (18)	0.0028 (18)	0.0086 (18)
C5	0.0405 (17)	0.0397 (17)	0.038 (2)	−0.0011 (15)	0.0052 (16)	0.0014 (15)
C6	0.0463 (18)	0.0483 (18)	0.051 (2)	0.0055 (17)	−0.0026 (18)	0.0024 (18)
C7	0.054 (2)	0.0466 (18)	0.041 (2)	−0.0003 (18)	−0.0017 (18)	−0.0044 (17)
C8	0.0449 (17)	0.0445 (18)	0.050 (2)	−0.0021 (18)	0.0023 (18)	−0.0055 (18)
C9	0.0443 (17)	0.0461 (19)	0.049 (2)	−0.0012 (19)	−0.0062 (18)	0.0010 (17)
C10	0.0470 (17)	0.0483 (18)	0.045 (2)	0.0022 (17)	0.0018 (17)	0.0001 (17)
C11	0.072 (2)	0.087 (3)	0.047 (2)	0.008 (2)	−0.002 (2)	0.007 (2)
C12	0.060 (2)	0.103 (3)	0.100 (4)	0.011 (2)	0.022 (3)	−0.005 (3)
C13	0.094 (3)	0.104 (4)	0.071 (3)	0.039 (3)	−0.022 (3)	0.002 (3)

Geometric parameters (Å, º) top

Cl1—C1	1.783 (4)	C4—C5	1.464 (5)
O1—H1	0.8200	C5—C6	1.412 (5)
O1—C2	1.420 (4)	C5—C10	1.389 (5)
O4—C9	1.369 (4)	C6—H6	0.9300
O4—C13	1.433 (5)	C6—C7	1.398 (5)
O2—C7	1.384 (4)	C7—C8	1.379 (5)
O2—C11	1.420 (4)	C8—C9	1.415 (5)
O3—C8	1.369 (4)	C9—C10	1.373 (5)
O3—C12	1.410 (4)	C10—H10	0.9300
N1—C3	1.462 (4)	C11—H11C	0.9600
N1—C4	1.281 (4)	C11—H11B	0.9600
C1—H1B	0.9700	C11—H11A	0.9600
C1—H1A	0.9700	C12—H12C	0.9600
C1—C2	1.508 (5)	C12—H12B	0.9600
C2—H2	0.9800	C12—H12A	0.9600
C2—C3	1.507 (4)	C13—H13C	0.9600
C3—H3A	0.9700	C13—H13A	0.9600
C3—H3B	0.9700	C13—H13B	0.9600
C4—H4	0.9300

Cl1—C1—H1B	109.4	C2—C3—H3B	109.1
Cl1—C1—H1A	109.4	C3—C2—C1	112.7 (3)
O1—C2—C1	107.5 (3)	C3—C2—H2	109.5
O1—C2—H2	109.5	H3A—C3—H3B	107.8
O1—C2—C3	108.0 (3)	C4—N1—C3	117.2 (3)
O4—C9—C8	114.9 (3)	C5—C4—H4	117.1
O4—C9—C10	123.9 (3)	C5—C6—H6	119.6
O4—C13—H13C	109.5	C5—C10—H10	120.3
O4—C13—H13A	109.5	C6—C5—C4	118.0 (3)
O4—C13—H13B	109.5	C7—O2—C11	118.8 (3)
O2—C7—C6	124.8 (3)	C7—C6—C5	120.7 (3)
O2—C11—H11C	109.5	C7—C6—H6	119.6
O2—C11—H11B	109.5	C7—C8—C9	119.9 (3)
O2—C11—H11A	109.5	C8—O3—C12	115.3 (3)
O3—C8—C7	119.4 (3)	C8—C7—O2	116.2 (3)
O3—C8—C9	120.6 (3)	C8—C7—C6	119.0 (3)
O3—C12—H12C	109.5	C9—O4—C13	117.9 (3)
O3—C12—H12B	109.5	C9—C10—C5	119.5 (3)
O3—C12—H12A	109.5	C9—C10—H10	120.3
N1—C3—C2	112.5 (3)	C10—C5—C4	122.3 (3)
N1—C3—H3A	109.1	C10—C5—C6	119.7 (3)
N1—C3—H3B	109.1	C10—C9—C8	121.2 (3)
N1—C4—H4	117.1	H11C—C11—H11B	109.5
N1—C4—C5	125.7 (3)	H11C—C11—H11A	109.5
C1—C2—H2	109.5	H11B—C11—H11A	109.5
H1B—C1—H1A	108.0	H12C—C12—H12B	109.5
C2—O1—H1	109.5	H12C—C12—H12A	109.5
C2—C1—Cl1	111.3 (3)	H12B—C12—H12A	109.5
C2—C1—H1B	109.4	H13C—C13—H13A	109.5
C2—C1—H1A	109.4	H13C—C13—H13B	109.5
C2—C3—H3A	109.1	H13A—C13—H13B	109.5

Cl1—C1—C2—O1	172.3 (2)	C5—C6—C7—O2	−178.8 (3)
Cl1—C1—C2—C3	−68.8 (4)	C5—C6—C7—C8	−0.2 (5)
O1—C2—C3—N1	−57.9 (4)	C6—C5—C10—C9	0.8 (5)
O4—C9—C10—C5	178.9 (3)	C6—C7—C8—O3	−174.9 (3)
O2—C7—C8—O3	3.9 (4)	C6—C7—C8—C9	1.3 (5)
O2—C7—C8—C9	−180.0 (3)	C7—C8—C9—O4	179.9 (3)
O3—C8—C9—O4	−4.0 (4)	C7—C8—C9—C10	−1.4 (5)
O3—C8—C9—C10	174.8 (3)	C8—C9—C10—C5	0.3 (5)
N1—C4—C5—C6	−175.3 (3)	C10—C5—C6—C7	−0.9 (5)
N1—C4—C5—C10	6.1 (5)	C11—O2—C7—C6	−13.6 (5)
C1—C2—C3—N1	−176.5 (3)	C11—O2—C7—C8	167.7 (3)
C3—N1—C4—C5	−176.9 (3)	C12—O3—C8—C7	−84.2 (4)
C4—N1—C3—C2	−111.9 (3)	C12—O3—C8—C9	99.6 (4)
C4—C5—C6—C7	−179.5 (3)	C13—O4—C9—C8	−177.6 (4)
C4—C5—C10—C9	179.4 (3)	C13—O4—C9—C10	3.7 (5)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1···N1ⁱ	0.82	2.08	2.870 (4)	162

Symmetry code: (i) x+1/2, −y+3/2, −z+1.

Experimental details

Crystal data
Chemical formula	C₁₃H₁₈ClNO₄
M_r	287.73
Crystal system, space group	Orthorhombic, P2₁2₁2₁
Temperature (K)	296
a, b, c (Å)	6.5332 (12), 8.888 (2), 25.29 (3)
V (Å³)	1468.7 (16)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.27
Crystal size (mm)	0.32 × 0.28 × 0.20

Data collection
Diffractometer	Xcalibur, Eos diffractometer
Absorption correction	Multi-scan (CrysAlis PRO; Oxford Diffraction 2009)
T_min, T_max	0.760, 1.0
No. of measured, independent and observed [I > 2σ(I)] reflections	3967, 2695, 1599
R_int	0.045
(sin θ/λ)_max (Å⁻¹)	0.625

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.051, 0.126, 1.06
No. of reflections	2695
No. of parameters	176
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.32, −0.21
Absolute structure	Flack (1983), 931 Friedel pairs
Absolute structure parameter	0.18 (13)

Computer programs: CrysAlis PRO (Oxford Diffraction, 2009), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), OLEX2 (Dolomanov et al., 2009).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1···N1ⁱ	0.82	2.08	2.870 (4)	162

Symmetry code: (i) x+1/2, −y+3/2, −z+1.

Acknowledgements

The authors thank the NSFC (81072532) for financial support and Professor Zhihua Mao (Sichuan University) for the X-ray measurements.

References

Brickner, S. J., Hutchinson, D. K., Barbachyn, M. R., Manninen, P. R., Ulanowicz, D. A., Garmon, S. A., Grega, K. C., Hendges, S. K., Toops, D. S., Ford, C. W. & Zurenko, G. E. (1996). J. Med. Chem. 39, 673–679. CrossRef CAS PubMed Web of Science Google Scholar
Dolomanov, O. V., Bourhis, L. J., Gildea, R. J., Howard, J. A. K. & Puschmann, H. (2009). J. Appl. Cryst. 42, 339–341. Web of Science CrossRef CAS IUCr Journals Google Scholar
Flack, H. D. (1983). Acta Cryst. A39, 876–881. CrossRef CAS Web of Science IUCr Journals Google Scholar
Imbordino, R. J., Perrault, W. R. & Reeder, M. R. (2007). WO Patent 116284. Google Scholar
Oxford Diffraction (2009). CrysAlis PRO. Oxford Diffraction Ltd, Yarnton, Oxfordshire, England. Google Scholar
Perrault, W. R., Pearlman, B. A. & Godrej, D. B. (2002). WO Patent 02085849. Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Zhao, X. Y., Ma, Y. R. & Xu, Z. (2006). West China J. Pharm. Sci. 22, 180–181. Google Scholar