10-Benzyl-10H-phenothia­zine 9-oxide

Xu, Z.; Sun, Y.; Yang, L.; Wang, Q.

doi:10.1107/S160053680902577X

organic compounds

CRYSTALLOGRAPHIC
COMMUNICATIONS

ISSN: 2056-9890

Volume 65| Part 8| August 2009| Page o1799

doi:10.1107/S160053680902577X

Open

access

ADDENDA AND ERRATA

A correction has been published for this article. To view the correction, click here.

10-Benzyl-10H-phenothiazine 9-oxide

Zhouqing Xu,^a Yanchun Sun,^b Lei Yang ^a and Qiang Wang ^a ^*

^aDepartment of Physics & Chemistry, Henan Polytechnic University, Jiao Zuo 454000, People's Republic of China, and ^bDepartment of Medicine, Hebi College of Vocation and Technology, He Bi 458030, People's Republic of China
^*Correspondence e-mail: wangqiang@hpu.edu.cn

(Received 22 June 2009; accepted 3 July 2009; online 8 July 2009)

In the title compound, C₁₉H₁₅NOS, the butterfly angle between the mean planes defined by the S, N and phenyl C atoms of the two wings of the phenothiazine unit is 23.4 (1)°. In the crystal, a supramolecular two-dimensional arrangement arises from weak intermolecular C—H⋯O interactions.

Related literature

For applications of phenothiazines, see: Miller et al. (1999 ); Wermuth (2003 ); Wang et al. (2008 ); Lam et al. (2001 ). For the synthesis, see: Zhu et al. (2006 ); Gilman et al. (1954 ).

Experimental

Crystal data

C₁₉H₁₅NOS
M_r = 305.38
Monoclinic, P 2₁ /n
a = 6.2819 (4) Å
b = 11.9259 (8) Å
c = 20.3220 (14) Å
β = 94.6140 (10)°
V = 1517.54 (18) Å³
Z = 4
Mo Kα radiation
μ = 0.21 mm⁻¹
T = 296 K
0.30 × 0.22 × 0.19 mm

Data collection

Bruker APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 2003 ) T_min = 0.939, T_max = 0.961
7251 measured reflections
2511 independent reflections
1872 reflections with I > 2σ(I)
R_int = 0.032

Refinement

R[F² > 2σ(F²)] = 0.036
wR(F²) = 0.094
S = 1.02
2511 reflections
199 parameters
H-atom parameters constrained
Δρ_max = 0.17 e Å⁻³
Δρ_min = −0.23 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C13—H13B⋯O1ⁱ	0.97	2.52	3.431 (2)	157
C18—H18⋯O1ⁱⁱ	0.93	2.57	3.442 (3)	157
Symmetry codes: (i) $[-x+{\script{1\over 2}}, y+{\script{1\over 2}}, -z+{\script{3\over 2}}]$ ; (ii) x, y+1, z.

Data collection: APEX2 (Bruker, 2003 ); cell refinement: SAINT (Bruker, 2001 ); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL.

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S160053680902577X/pv2174sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S160053680902577X/pv2174Isup2.hkl

checkCIF report

Comment top

Phenothiazine molecule is a well known heterocycle. The phenothiazine structure occurs in many synthetic dyes, electroluminescent materials (Miller et al., 1999) and drugs, especially various antipsychotic drugs, e.g., chlorpromazine and promethazine (Wermuth, 2003). Recently, some new applications of phenothazine derivatives have been found in medicines, such as antitubercular (Wang et al., 2008) and antitumor (Lam et al., 2001). As a part of our programme devoted to the new applications of phenothazine derivatives in medicne, we report herein the crystal structure of the title compound, (I).

The molecular structure of (I) is shown in Fig. 1, with its respective labels. The butterfly angle between the mean-planes defined by atoms S1/N1/C1-C6 and S1/N1/C7-C12 is 23.4 (1) °. The crystal packing (Fig. 2) consists of two-dimensional infinite plane along the a axis generated by intermolecular interactions of the weak C—H···O hydrogen bonds (details are in Table 1).

Related literature top

For applications of phenothiazines, see: Miller et al. (1999); Wermuth (2003); Wang et al. (2008); Lam et al. (2001). For the synthesis, see: Zhu et al. (2006); Gilman et al. (1954).

Experimental top

All reagents were of analytical grade. The title compound was prepared according to a literature method (Zhu et al., 2006; Gilman et al., 1954) from N-benzylphenothiazine. The purity of the compound was checked by determining its melting point. It was characterized by recording its infrared spectra and elemental analyses. Single crystals of the title compound were obtained by slow evaporation of its ethanol solution. The X-ray diffraction studies were made at room temperature.

Computing details top

Data collection: APEX2 (Bruker, 2003); cell refinement: SAINT (Bruker, 2003); data reduction: SAINT (Bruker, 2001); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures top

	Fig. 1. The molecular structure of the title molecule, with the atom-numbering scheme. Displacement ellipsoids are drawn at the 30% probability level.
	Fig. 2. A partial packing diagram of the title compound. Hydrogen bonds are shown as dashed lines, viewed down the a axis.

10-Benzyl-10H-phenothiazine 9-oxide top

Crystal data top

C₁₉H₁₅NOS	F(000) = 640
M_r = 305.38	D_x = 1.337 Mg m⁻³
Monoclinic, P2₁/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 1664 reflections
a = 6.2819 (4) Å	θ = 2.6–22.2°
b = 11.9259 (8) Å	µ = 0.21 mm⁻¹
c = 20.3220 (14) Å	T = 296 K
β = 94.614 (1)°	Block, yellow
V = 1517.54 (18) Å³	0.30 × 0.22 × 0.19 mm
Z = 4

Data collection top

Bruker SMART CCD area-detector diffractometer	2511 independent reflections
Radiation source: fine-focus sealed tube	1872 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.032
ϕ and ω scans	θ_max = 24.5°, θ_min = 2.0°
Absorption correction: multi-scan (SADABS; Sheldrick, 2003)	h = −7→6
T_min = 0.939, T_max = 0.961	k = −13→13
7251 measured reflections	l = −23→23

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)] = 0.036	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.094	H-atom parameters constrained
S = 1.02	w = 1/[σ²(F_o²) + (0.0425P)² + 0.2518P] where P = (F_o² + 2F_c²)/3
2511 reflections	(Δ/σ)_max = 0.001
199 parameters	Δρ_max = 0.17 e Å⁻³
0 restraints	Δρ_min = −0.23 e Å⁻³

Crystal data top

C₁₉H₁₅NOS	V = 1517.54 (18) Å³
M_r = 305.38	Z = 4
Monoclinic, P2₁/n	Mo Kα radiation
a = 6.2819 (4) Å	µ = 0.21 mm⁻¹
b = 11.9259 (8) Å	T = 296 K
c = 20.3220 (14) Å	0.30 × 0.22 × 0.19 mm
β = 94.614 (1)°

Data collection top

Bruker SMART CCD area-detector diffractometer	2511 independent reflections
Absorption correction: multi-scan (SADABS; Sheldrick, 2003)	1872 reflections with I > 2σ(I)
T_min = 0.939, T_max = 0.961	R_int = 0.032
7251 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.036	0 restraints
wR(F²) = 0.094	H-atom parameters constrained
S = 1.02	Δρ_max = 0.17 e Å⁻³
2511 reflections	Δρ_min = −0.23 e Å⁻³
199 parameters

Special details top

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 > 2sigma(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
N1	0.2291 (2)	0.28879 (12)	0.65659 (8)	0.0377 (4)
O1	0.2735 (3)	−0.01747 (11)	0.65821 (7)	0.0601 (4)
S1	0.11841 (9)	0.04344 (4)	0.61145 (3)	0.04963 (19)
C1	0.0471 (3)	0.24089 (15)	0.67982 (9)	0.0379 (5)
C2	−0.0702 (3)	0.29706 (17)	0.72559 (10)	0.0470 (5)
H2	−0.0251	0.3672	0.7411	0.056*
C3	−0.2502 (3)	0.2501 (2)	0.74777 (12)	0.0559 (6)
H3	−0.3216	0.2879	0.7794	0.067*
C4	−0.3281 (4)	0.1485 (2)	0.72440 (12)	0.0615 (7)
H4	−0.4534	0.1190	0.7387	0.074*
C5	−0.2173 (3)	0.09217 (19)	0.67984 (11)	0.0553 (6)
H5	−0.2685	0.0235	0.6636	0.066*
C6	−0.0284 (3)	0.13530 (16)	0.65792 (10)	0.0429 (5)
C7	0.3155 (3)	0.25083 (15)	0.59956 (9)	0.0385 (5)
C8	0.4588 (3)	0.31695 (18)	0.56709 (11)	0.0490 (5)
H8	0.4994	0.3865	0.5845	0.059*
C9	0.5405 (4)	0.2812 (2)	0.51022 (12)	0.0613 (6)
H9	0.6383	0.3261	0.4904	0.074*
C10	0.4801 (4)	0.1798 (2)	0.48169 (12)	0.0644 (7)
H10	0.5326	0.1571	0.4423	0.077*
C11	0.3413 (4)	0.11342 (18)	0.51272 (11)	0.0551 (6)
H11	0.3003	0.0447	0.4942	0.066*
C12	0.2605 (3)	0.14667 (16)	0.57131 (10)	0.0424 (5)
C13	0.3051 (3)	0.39597 (15)	0.68456 (10)	0.0400 (5)
H13A	0.4581	0.4007	0.6815	0.048*
H13B	0.2798	0.3974	0.7310	0.048*
C14	0.2012 (3)	0.49772 (15)	0.65152 (9)	0.0380 (5)
C15	0.0249 (4)	0.49180 (19)	0.60717 (11)	0.0571 (6)
H15	−0.0329	0.4223	0.5951	0.068*
C16	−0.0678 (4)	0.5888 (2)	0.58025 (13)	0.0713 (7)
H16	−0.1875	0.5843	0.5503	0.086*
C17	0.0174 (4)	0.6915 (2)	0.59780 (13)	0.0658 (7)
H17	−0.0449	0.7566	0.5799	0.079*
C18	0.1927 (4)	0.69818 (18)	0.64129 (12)	0.0577 (6)
H18	0.2498	0.7679	0.6531	0.069*
C19	0.2860 (3)	0.60252 (16)	0.66792 (10)	0.0470 (5)
H19	0.4072	0.6080	0.6972	0.056*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
N1	0.0403 (9)	0.0307 (9)	0.0428 (9)	0.0004 (8)	0.0072 (7)	0.0001 (7)
O1	0.0760 (11)	0.0362 (8)	0.0685 (10)	0.0096 (8)	0.0085 (9)	0.0108 (7)
S1	0.0607 (4)	0.0344 (3)	0.0537 (4)	−0.0069 (3)	0.0040 (3)	−0.0047 (2)
C1	0.0382 (11)	0.0337 (10)	0.0415 (11)	0.0043 (9)	0.0021 (9)	0.0082 (9)
C2	0.0483 (13)	0.0402 (12)	0.0538 (13)	0.0088 (10)	0.0121 (10)	0.0072 (10)
C3	0.0492 (14)	0.0589 (15)	0.0617 (15)	0.0157 (12)	0.0167 (11)	0.0140 (12)
C4	0.0402 (13)	0.0721 (17)	0.0739 (17)	0.0005 (13)	0.0153 (12)	0.0190 (14)
C5	0.0473 (13)	0.0522 (13)	0.0655 (15)	−0.0094 (11)	−0.0006 (12)	0.0110 (12)
C6	0.0419 (12)	0.0407 (12)	0.0458 (12)	−0.0003 (10)	0.0012 (9)	0.0053 (9)
C7	0.0375 (11)	0.0346 (11)	0.0437 (12)	0.0061 (9)	0.0047 (9)	0.0040 (9)
C8	0.0474 (13)	0.0426 (12)	0.0586 (14)	0.0012 (10)	0.0142 (11)	0.0047 (11)
C9	0.0613 (15)	0.0594 (15)	0.0664 (16)	0.0094 (13)	0.0250 (12)	0.0106 (13)
C10	0.0782 (18)	0.0658 (17)	0.0527 (15)	0.0166 (15)	0.0258 (13)	0.0029 (13)
C11	0.0688 (16)	0.0474 (13)	0.0493 (13)	0.0133 (12)	0.0061 (12)	−0.0056 (11)
C12	0.0449 (12)	0.0386 (11)	0.0435 (12)	0.0064 (10)	0.0032 (9)	0.0025 (9)
C13	0.0406 (11)	0.0351 (11)	0.0441 (11)	−0.0019 (9)	0.0024 (9)	−0.0017 (9)
C14	0.0405 (12)	0.0341 (11)	0.0398 (11)	0.0028 (9)	0.0059 (9)	−0.0015 (9)
C15	0.0581 (15)	0.0467 (13)	0.0640 (15)	−0.0007 (11)	−0.0105 (12)	0.0036 (11)
C16	0.0649 (17)	0.0728 (18)	0.0735 (17)	0.0149 (15)	−0.0109 (13)	0.0165 (15)
C17	0.0839 (19)	0.0470 (15)	0.0682 (16)	0.0211 (14)	0.0174 (15)	0.0187 (12)
C18	0.0831 (18)	0.0347 (12)	0.0580 (14)	0.0000 (12)	0.0225 (13)	0.0035 (11)
C19	0.0572 (14)	0.0402 (12)	0.0443 (12)	−0.0051 (11)	0.0078 (10)	−0.0017 (10)

Geometric parameters (Å, º) top

N1—C1	1.394 (2)	C9—C10	1.381 (3)
N1—C7	1.394 (2)	C9—H9	0.9300
N1—C13	1.463 (2)	C10—C11	1.368 (3)
O1—S1	1.4934 (15)	C10—H10	0.9300
S1—C6	1.756 (2)	C11—C12	1.389 (3)
S1—C12	1.759 (2)	C11—H11	0.9300
C1—C2	1.402 (3)	C13—C14	1.509 (2)
C1—C6	1.405 (3)	C13—H13A	0.9700
C2—C3	1.370 (3)	C13—H13B	0.9700
C2—H2	0.9300	C14—C15	1.372 (3)
C3—C4	1.377 (3)	C14—C19	1.389 (3)
C3—H3	0.9300	C15—C16	1.388 (3)
C4—C5	1.363 (3)	C15—H15	0.9300
C4—H4	0.9300	C16—C17	1.372 (3)
C5—C6	1.399 (3)	C16—H16	0.9300
C5—H5	0.9300	C17—C18	1.358 (3)
C7—C12	1.400 (3)	C17—H17	0.9300
C7—C8	1.401 (3)	C18—C19	1.374 (3)
C8—C9	1.370 (3)	C18—H18	0.9300
C8—H8	0.9300	C19—H19	0.9300

C1—N1—C7	122.21 (16)	C11—C10—C9	118.5 (2)
C1—N1—C13	118.50 (15)	C11—C10—H10	120.8
C7—N1—C13	118.04 (15)	C9—C10—H10	120.8
O1—S1—C6	107.77 (9)	C10—C11—C12	121.3 (2)
O1—S1—C12	107.82 (9)	C10—C11—H11	119.3
C6—S1—C12	96.94 (9)	C12—C11—H11	119.3
N1—C1—C2	121.18 (17)	C11—C12—C7	120.65 (19)
N1—C1—C6	121.68 (18)	C11—C12—S1	115.57 (16)
C2—C1—C6	117.14 (18)	C7—C12—S1	123.25 (15)
C3—C2—C1	121.0 (2)	N1—C13—C14	114.44 (15)
C3—C2—H2	119.5	N1—C13—H13A	108.6
C1—C2—H2	119.5	C14—C13—H13A	108.6
C2—C3—C4	121.7 (2)	N1—C13—H13B	108.6
C2—C3—H3	119.1	C14—C13—H13B	108.6
C4—C3—H3	119.1	H13A—C13—H13B	107.6
C5—C4—C3	118.5 (2)	C15—C14—C19	118.54 (18)
C5—C4—H4	120.8	C15—C14—C13	123.23 (17)
C3—C4—H4	120.8	C19—C14—C13	118.22 (17)
C4—C5—C6	121.5 (2)	C14—C15—C16	120.5 (2)
C4—C5—H5	119.3	C14—C15—H15	119.8
C6—C5—H5	119.3	C16—C15—H15	119.8
C5—C6—C1	120.1 (2)	C17—C16—C15	119.9 (2)
C5—C6—S1	115.95 (16)	C17—C16—H16	120.0
C1—C6—S1	123.43 (15)	C15—C16—H16	120.0
N1—C7—C12	121.97 (17)	C18—C17—C16	120.0 (2)
N1—C7—C8	121.10 (18)	C18—C17—H17	120.0
C12—C7—C8	116.93 (19)	C16—C17—H17	120.0
C9—C8—C7	121.4 (2)	C17—C18—C19	120.4 (2)
C9—C8—H8	119.3	C17—C18—H18	119.8
C7—C8—H8	119.3	C19—C18—H18	119.8
C8—C9—C10	121.2 (2)	C18—C19—C14	120.6 (2)
C8—C9—H9	119.4	C18—C19—H19	119.7
C10—C9—H9	119.4	C14—C19—H19	119.7

C7—N1—C1—C2	−162.60 (17)	C7—C8—C9—C10	1.7 (3)
C13—N1—C1—C2	4.4 (3)	C8—C9—C10—C11	−2.1 (4)
C7—N1—C1—C6	16.6 (3)	C9—C10—C11—C12	0.5 (3)
C13—N1—C1—C6	−176.46 (16)	C10—C11—C12—C7	1.5 (3)
N1—C1—C2—C3	179.35 (18)	C10—C11—C12—S1	−170.45 (17)
C6—C1—C2—C3	0.1 (3)	N1—C7—C12—C11	176.90 (18)
C1—C2—C3—C4	−2.6 (3)	C8—C7—C12—C11	−1.8 (3)
C2—C3—C4—C5	2.4 (3)	N1—C7—C12—S1	−11.8 (3)
C3—C4—C5—C6	0.1 (3)	C8—C7—C12—S1	169.48 (15)
C4—C5—C6—C1	−2.5 (3)	O1—S1—C12—C11	90.65 (17)
C4—C5—C6—S1	169.87 (17)	C6—S1—C12—C11	−158.12 (16)
N1—C1—C6—C5	−176.90 (17)	O1—S1—C12—C7	−81.06 (18)
C2—C1—C6—C5	2.3 (3)	C6—S1—C12—C7	30.17 (18)
N1—C1—C6—S1	11.3 (3)	C1—N1—C13—C14	−86.1 (2)
C2—C1—C6—S1	−169.46 (15)	C7—N1—C13—C14	81.4 (2)
O1—S1—C6—C5	−90.78 (17)	N1—C13—C14—C15	11.1 (3)
C12—S1—C6—C5	157.95 (16)	N1—C13—C14—C19	−170.27 (17)
O1—S1—C6—C1	81.32 (17)	C19—C14—C15—C16	−1.0 (3)
C12—S1—C6—C1	−29.95 (18)	C13—C14—C15—C16	177.7 (2)
C1—N1—C7—C12	−16.3 (3)	C14—C15—C16—C17	0.2 (4)
C13—N1—C7—C12	176.65 (16)	C15—C16—C17—C18	0.2 (4)
C1—N1—C7—C8	162.34 (17)	C16—C17—C18—C19	0.1 (4)
C13—N1—C7—C8	−4.7 (3)	C17—C18—C19—C14	−0.9 (3)
N1—C7—C8—C9	−178.49 (19)	C15—C14—C19—C18	1.3 (3)
C12—C7—C8—C9	0.2 (3)	C13—C14—C19—C18	−177.42 (19)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C13—H13B···O1ⁱ	0.97	2.52	3.431 (2)	157
C18—H18···O1ⁱⁱ	0.93	2.57	3.442 (3)	157

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

Experimental details

Crystal data
Chemical formula	C₁₉H₁₅NOS
M_r	305.38
Crystal system, space group	Monoclinic, P2₁/n
Temperature (K)	296
a, b, c (Å)	6.2819 (4), 11.9259 (8), 20.3220 (14)
β (°)	94.614 (1)
V (Å³)	1517.54 (18)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.21
Crystal size (mm)	0.30 × 0.22 × 0.19

Data collection
Diffractometer	Bruker SMART CCD area-detector diffractometer
Absorption correction	Multi-scan (SADABS; Sheldrick, 2003)
T_min, T_max	0.939, 0.961
No. of measured, independent and observed [I > 2σ(I)] reflections	7251, 2511, 1872
R_int	0.032
(sin θ/λ)_max (Å⁻¹)	0.582

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.036, 0.094, 1.02
No. of reflections	2511
No. of parameters	199
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.17, −0.23

Computer programs: APEX2 (Bruker, 2003), SAINT (Bruker, 2003), SAINT (Bruker, 2001), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C13—H13B···O1ⁱ	0.97	2.52	3.431 (2)	157
C18—H18···O1ⁱⁱ	0.93	2.57	3.442 (3)	157

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

Acknowledgements

This work was supported by the Foundation of Henan Polytechnic University for Doctor Teachers, and the authors thank Ms Q. F. Wang for her support with the single-crystal X-ray diffraction data collection.

References

Bruker (2001). SAINT. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Bruker (2003). APEX2. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Gilman, H., Ingham, R. K., Champaigne, J. F., Diehl, J. W. & Ranck, R. O. (1954). J. Org. Chem. 19, 560–569. CrossRef CAS Web of Science Google Scholar
Lam, M., Oleinick, N. L. & Nieminen, A. L. (2001). J. Biol. Chem. 276, 47379–47386. Web of Science CrossRef PubMed CAS Google Scholar
Miller, M. T., Gantzel, P. K. & Karpishin, T. (1999). J. Am. Chem. Soc. 121, 4292–4293. Web of Science CSD CrossRef CAS Google Scholar
Sheldrick, G. M. (2003). SADABS. University of Göttingen, Germany. Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Wang, J., Dong, M., Liang, J., Chang, Z., Feng, S., Wang, H. & Ding, N. (2008). Chin. J. Lab. Diagn. 12, 381–382. Google Scholar
Wermuth, C. G. (2003). The Practice of Medicinal Chemistry, 2th ed. London: Acdemic. Google Scholar
Zhu, X., Zhang, J. & Cheng, J. (2006). J. Org. Chem. 71, 7007–7015. Web of Science CrossRef PubMed CAS Google Scholar