2-(1,3-Benzothia­zol-2-ylsulfan­yl)-1-phenyl­ethanone

Loghmani-Khouzani, H.; Hajiheidari, D.; Robinson, W.T.; Abdul Rahman, N.; Kia, R.

doi:10.1107/S1600536809033121

organic compounds

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ISSN: 2056-9890

Volume 65| Part 10| October 2009| Page o2441

doi:10.1107/S1600536809033121

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2-(1,3-Benzothiazol-2-ylsulfanyl)-1-phenylethanone

Hossein Loghmani-Khouzani,^a ^* Dariush Hajiheidari,^a Ward T. Robinson,^b Noorsaadah Abdul Rahman ^b and Reza Kia ^c ‡

^aChemistry Department, University of Isfahan, Isfahan 81746-73441, Iran, ^bDepartment of Chemistry, University of Malaya, 50603 Kuala Lumpur, Malaysia, and ^cDepartment of Chemistry, Science and Research Campus, Islamic Azad University, Poonak, Tehran, Iran
^*Correspondence e-mail: loghmani_h@yahoo.com

(Received 10 August 2009; accepted 19 August 2009; online 12 September 2009)

In the molecule of the title compound, C₁₅H₁₁NOS₂, the 1,3-benzothiazole ring is oriented at a dihedral angle of 6.61 (6)° with respect to the phenyl ring. In the crystal structure, intermolecular C—H⋯O interactions link the molecules in a herring-bone arrangement along the b axis and π–π contacts between the thiazole and phenyl rings [centroid–centroid distance = 3.851 (1) Å] may further stabilize the structure.

Related literature

For applications of the title compound in organic synthesis, see: Marco et al. (1995 ); Fuju et al. (1988 ); Ni et al. (2006 ); Grossert et al. (1984 ); Oishi et al. (1988 ); Antane et al. (2004 ). For its biological activity, see: Padmavathi et al. (2008 ).

Experimental

Crystal data

C₁₅H₁₁NOS₂
M_r = 285.37
Orthorhombic, P 2₁ 2₁ 2₁
a = 5.1060 (1) Å
b = 14.6220 (3) Å
c = 17.3920 (4) Å
V = 1298.49 (5) Å³
Z = 4
Mo Kα radiation
μ = 0.40 mm⁻¹
T = 295 K
0.45 × 0.32 × 0.17 mm

Data collection

Bruker SMART APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2005 ) T_min = 0.841, T_max = 0.935
14309 measured reflections
3734 independent reflections
3576 reflections with I > 2σ(I)
R_int = 0.024

Refinement

R[F² > 2σ(F²)] = 0.027
wR(F²) = 0.068
S = 1.07
3734 reflections
172 parameters
H-atom parameters constrained
Δρ_max = 0.31 e Å⁻³
Δρ_min = −0.16 e Å⁻³
Absolute structure: Flack (1983 ), 1550 Friedel pairs
Flack parameter: 0.01 (5)

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C2—H2A⋯O1ⁱ	0.93	2.51	3.2299 (17)	135
Symmetry code: (i) $[-x, y+{\script{1\over 2}}, -z+{\script{3\over 2}}]$ .

Data collection: APEX2 (Bruker, 2005); cell refinement: SAINT (Bruker, 2005); data reduction: SAINT; program(s) used to solve structure: SIR2004 (Burla et al., 2004 ); program(s) used to refine structure: SHELXTL (Sheldrick, 2008 ); molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2009 ).

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536809033121/hk2756sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536809033121/hk2756Isup2.hkl

checkCIF report

Comment top

2-(Benzo[d]thiaazol-2-ylthio)-1-phenylethanone is of great importance in organic synthesis and β-keto-sulfones are a very important group of intermediates as they are precursors for Michael and Knoevenagel reactions and are used in the preparation of acetylenes, allenes, chalcones, vinyl sulfones, polyfunctionalized 4H-pyrans and ketones (Marco et al., 1995; Fuju et al., 1988; Ni et al., 2006). In addition, β-keto-sulfones can be converted into optically active β-hydroxy-sulfones, halomethyl and dihalomethyl sulfones. Halomethyl and dihalomethyl sulfones are very good α-carbanion stabilizing substituents and precursors for the preparation of alkenes, aziridines, epoxides and β-hydroxy-sulfones. Haloalkyl sulfones are useful in preventing aquatic organisms from attaching to fishing nets and ship hulls (Grossert et al., 1984; Oishi et al., 1988; Antane et al., 2004). They also possess other biological properties such as herbicidal, bactericidal antifungal and insecticidal. Recently sulfone-linked heterocycles were prepared and have been showed antimicrobial activity (Padmavathi et al., 2008). We prepared the title compound as a precursor for the synthesis of gem-difluoromethylene-containing heterocycle, and reported herein its crystal structure.

In the molecule of the title compound, (Fig. 1), the benzothiazole ring is oriented with respect to the phenyl ring at a dihedral angle of 6.61 (6)°. In the crystal structure, intermolecular C-H···O interactions (Table 1) link the molecules in herringbone mode along the b axis (Fig. 2), in which they may be effective in the stabilization of the structure. The π–π contact between the thiazole and phenyl rings, Cg1—Cg2ⁱ, [symmetry code: (i) x - 1, y, z, where Cg1 and Cg2 are centroids of the rings (S1/N1/C1/C6/C7) and (C1-C6), respectively] may further stabilize the structure, with centroid-centroid distance of 3.851 (1) Å.

Related literature top

For applications of the title compound in organic synthesis, see: Marco et al. (1995); Fuju et al. (1988); Ni et al. (2006); Grossert et al. (1984); Oishi et al. (1988); Antane et al. (2004). For its biological activity, see: Padmavathi et al. (2008).

Experimental top

For the preparation of the title compound, sodium carbonate (4.5 mmol) was added to a stirred solution of 2-mercaptobenzothiazole (3 mmol) in ethanol (15 ml) and water (15 ml) and stirred at room temperature for 30 min. α-Bromoacetophenone (3 mmol) was added to the reaction mixture and stirring was continued for 1h. The reaction was monitored by TLC and after 60 min showed the complete disappearance of the starting material. The reaction mixture was poured into HCl (1M, 100 ml) containing crushed ice (50 g). The product was filtered under vacuum and filtrate washed with ice-cold ethanol (10 ml) and water (10 ml). Recrystalization from petrol ether and filtration gave the title compound (m.p. 387-389 K). ¹H NMR (400 MHz; CDCl₃): 8.15-7.75 (m, 4H), 7.55-7.32 (m, 5H), 5.10 (s, 2H). ¹³C NMR (126 MHz; CDCl₃): 194.2 (C═O), 162.1, 151.8, 135.3, 134.2, 131.1, 126.7, 126.5, 124.7, 124.1, 119.8, 119.6, 37.5. Anal. Calcd. for CHNS: C, 63.13; H, 3.89; N, 4.91. Found: C, 63.07; H, 3.86; N, 4.93.

Computing details top

Data collection: APEX2 (Bruker, 2005); cell refinement: SAINT (Bruker, 2005); data reduction: SAINT (Bruker, 2005); program(s) used to solve structure: SIR2004 (Burla et al., 2004); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2009).

Figures top

	Fig. 1. The molecular structure of the title molecule with the atom-numbering scheme. Displacement ellipsoids are drawn at the 40% probability level
	Fig. 2. A partial packing diagram. Hydrogen bonds are shown as dashed lines.

2-(1,3-Benzothiazol-2-ylsulfanyl)-1-phenylethanone top

Crystal data top

C₁₅H₁₁NOS₂	D_x = 1.460 Mg m⁻³
M_r = 285.37	Melting point: 388 K
Orthorhombic, P2₁2₁2₁	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2ab	Cell parameters from 8370 reflections
a = 5.1060 (1) Å	θ = 2.3–30.5°
b = 14.6220 (3) Å	µ = 0.40 mm⁻¹
c = 17.3920 (4) Å	T = 295 K
V = 1298.49 (5) Å³	Block, pale-yellow
Z = 4	0.45 × 0.32 × 0.17 mm
F(000) = 592

Data collection top

Bruker SMART APEXII CCD area-detector diffractometer	3734 independent reflections
Radiation source: fine-focus sealed tube	3576 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.024
ϕ and ω scans	θ_max = 30.0°, θ_min = 2.7°
Absorption correction: multi-scan (SADABS; Bruker, 2005)	h = −7→6
T_min = 0.841, T_max = 0.935	k = −20→20
14309 measured reflections	l = −24→24

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)] = 0.027	H-atom parameters constrained
wR(F²) = 0.068	w = 1/[σ²(F_o²) + (0.0411P)² + 0.1348P] where P = (F_o² + 2F_c²)/3
S = 1.07	(Δ/σ)_max = 0.001
3734 reflections	Δρ_max = 0.31 e Å⁻³
172 parameters	Δρ_min = −0.16 e Å⁻³
0 restraints	Absolute structure: Flack (1983), 1550 Friedel pairs
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: 0.01 (5)

Crystal data top

C₁₅H₁₁NOS₂	V = 1298.49 (5) Å³
M_r = 285.37	Z = 4
Orthorhombic, P2₁2₁2₁	Mo Kα radiation
a = 5.1060 (1) Å	µ = 0.40 mm⁻¹
b = 14.6220 (3) Å	T = 295 K
c = 17.3920 (4) Å	0.45 × 0.32 × 0.17 mm

Data collection top

Bruker SMART APEXII CCD area-detector diffractometer	3734 independent reflections
Absorption correction: multi-scan (SADABS; Bruker, 2005)	3576 reflections with I > 2σ(I)
T_min = 0.841, T_max = 0.935	R_int = 0.024
14309 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.027	H-atom parameters constrained
wR(F²) = 0.068	Δρ_max = 0.31 e Å⁻³
S = 1.07	Δρ_min = −0.16 e Å⁻³
3734 reflections	Absolute structure: Flack (1983), 1550 Friedel pairs
172 parameters	Absolute structure parameter: 0.01 (5)
0 restraints

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
S1	0.32503 (6)	0.26829 (2)	0.744608 (17)	0.02052 (8)
S2	0.01546 (7)	0.10723 (2)	0.799872 (17)	0.02062 (8)
O1	−0.3471 (2)	−0.02751 (8)	0.84299 (6)	0.0341 (3)
N1	0.3955 (2)	0.19530 (7)	0.87979 (6)	0.0178 (2)
C1	0.5575 (2)	0.31781 (8)	0.80443 (7)	0.0173 (2)
C2	0.7199 (3)	0.39273 (9)	0.79124 (8)	0.0226 (3)
H2A	0.7112	0.4252	0.7453	0.027*
C3	0.8936 (3)	0.41738 (9)	0.84818 (8)	0.0240 (3)
H3A	1.0056	0.4666	0.8402	0.029*
C4	0.9045 (3)	0.36954 (9)	0.91801 (8)	0.0223 (3)
H4A	1.0230	0.3876	0.9557	0.027*
C5	0.7413 (3)	0.29592 (9)	0.93148 (7)	0.0188 (2)
H5A	0.7477	0.2648	0.9781	0.023*
C6	0.5668 (2)	0.26908 (9)	0.87415 (6)	0.0159 (2)
C7	0.2610 (3)	0.18779 (9)	0.81703 (7)	0.0171 (2)
C8	0.0085 (3)	0.05695 (9)	0.89446 (7)	0.0219 (2)
H8A	0.1752	0.0279	0.9053	0.026*
H8B	−0.0207	0.1041	0.9327	0.026*
C9	−0.2085 (3)	−0.01289 (9)	0.89821 (8)	0.0208 (3)
C10	−0.2437 (3)	−0.06360 (9)	0.97210 (8)	0.0197 (2)
C11	−0.4423 (3)	−0.12874 (9)	0.97723 (9)	0.0255 (3)
H11A	−0.5527	−0.1388	0.9355	0.031*
C12	−0.4758 (3)	−0.17854 (10)	1.04421 (9)	0.0296 (3)
H12A	−0.6096	−0.2215	1.0476	0.036*
C13	−0.3103 (3)	−0.16447 (9)	1.10627 (9)	0.0271 (3)
H13A	−0.3309	−0.1991	1.1507	0.032*
C14	−0.1145 (3)	−0.09906 (10)	1.10233 (8)	0.0271 (3)
H14A	−0.0055	−0.0891	1.1443	0.032*
C15	−0.0816 (3)	−0.04858 (10)	1.03552 (8)	0.0240 (3)
H15A	0.0493	−0.0044	1.0329	0.029*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
S1	0.02236 (15)	0.02516 (15)	0.01403 (13)	−0.00182 (12)	−0.00251 (11)	0.00181 (11)
S2	0.02335 (15)	0.02168 (14)	0.01685 (13)	−0.00322 (13)	−0.00214 (12)	−0.00344 (11)
O1	0.0360 (6)	0.0339 (5)	0.0323 (5)	−0.0120 (5)	−0.0132 (5)	0.0001 (4)
N1	0.0199 (5)	0.0188 (5)	0.0148 (5)	−0.0008 (4)	0.0011 (4)	−0.0018 (4)
C1	0.0166 (5)	0.0199 (5)	0.0154 (5)	0.0016 (4)	−0.0003 (4)	−0.0011 (4)
C2	0.0233 (6)	0.0220 (6)	0.0224 (6)	0.0001 (5)	0.0012 (5)	0.0051 (5)
C3	0.0223 (6)	0.0193 (6)	0.0303 (7)	−0.0026 (5)	−0.0002 (5)	0.0022 (5)
C4	0.0202 (6)	0.0231 (6)	0.0237 (6)	0.0003 (5)	−0.0041 (5)	−0.0042 (5)
C5	0.0207 (6)	0.0197 (6)	0.0160 (5)	0.0021 (5)	−0.0016 (4)	−0.0006 (4)
C6	0.0168 (5)	0.0164 (5)	0.0144 (5)	0.0018 (5)	0.0012 (4)	−0.0015 (4)
C7	0.0188 (6)	0.0175 (5)	0.0150 (5)	0.0002 (4)	0.0019 (4)	−0.0021 (4)
C8	0.0226 (6)	0.0233 (6)	0.0199 (5)	−0.0065 (6)	−0.0036 (5)	0.0005 (5)
C9	0.0197 (6)	0.0173 (6)	0.0253 (6)	−0.0004 (5)	−0.0011 (5)	−0.0033 (5)
C10	0.0172 (6)	0.0155 (5)	0.0265 (6)	0.0010 (4)	0.0018 (5)	−0.0026 (5)
C11	0.0211 (7)	0.0221 (6)	0.0333 (7)	−0.0042 (5)	−0.0012 (5)	−0.0039 (5)
C12	0.0255 (7)	0.0225 (6)	0.0409 (8)	−0.0054 (6)	0.0072 (6)	−0.0009 (6)
C13	0.0282 (7)	0.0229 (6)	0.0301 (7)	0.0020 (6)	0.0098 (6)	0.0020 (5)
C14	0.0280 (7)	0.0280 (7)	0.0253 (6)	−0.0025 (6)	−0.0006 (5)	0.0005 (6)
C15	0.0206 (6)	0.0228 (6)	0.0285 (6)	−0.0051 (5)	−0.0006 (5)	0.0006 (5)

Geometric parameters (Å, º) top

S1—C1	1.7365 (13)	C5—H5A	0.9300
S1—C7	1.7548 (13)	C8—C9	1.5080 (18)
S2—C7	1.7459 (13)	C8—H8A	0.9700
S2—C8	1.8022 (13)	C8—H8B	0.9700
O1—C9	1.2122 (16)	C9—C10	1.4945 (19)
N1—C7	1.2944 (16)	C10—C11	1.3943 (18)
N1—C6	1.3923 (17)	C10—C15	1.3964 (19)
C1—C2	1.3929 (18)	C11—C12	1.384 (2)
C1—C6	1.4073 (17)	C11—H11A	0.9300
C2—C3	1.3774 (19)	C12—C13	1.386 (2)
C2—H2A	0.9300	C12—H12A	0.9300
C3—C4	1.4026 (19)	C13—C14	1.385 (2)
C3—H3A	0.9300	C13—H13A	0.9300
C4—C5	1.3813 (19)	C14—C15	1.387 (2)
C4—H4A	0.9300	C14—H14A	0.9300
C5—C6	1.3934 (17)	C15—H15A	0.9300

C1—S1—C7	88.68 (6)	S2—C8—H8A	109.8
C7—S2—C8	97.66 (6)	C9—C8—H8B	109.8
C7—N1—C6	109.87 (11)	S2—C8—H8B	109.8
C2—C1—C6	121.32 (12)	H8A—C8—H8B	108.3
C2—C1—S1	129.51 (10)	O1—C9—C10	121.56 (13)
C6—C1—S1	109.17 (9)	O1—C9—C8	120.95 (12)
C3—C2—C1	118.08 (12)	C10—C9—C8	117.49 (11)
C3—C2—H2A	121.0	C11—C10—C15	119.22 (13)
C1—C2—H2A	121.0	C11—C10—C9	118.78 (12)
C2—C3—C4	121.17 (13)	C15—C10—C9	121.99 (12)
C2—C3—H3A	119.4	C12—C11—C10	120.20 (14)
C4—C3—H3A	119.4	C12—C11—H11A	119.9
C5—C4—C3	120.77 (12)	C10—C11—H11A	119.9
C5—C4—H4A	119.6	C11—C12—C13	120.13 (13)
C3—C4—H4A	119.6	C11—C12—H12A	119.9
C4—C5—C6	118.93 (12)	C13—C12—H12A	119.9
C4—C5—H5A	120.5	C14—C13—C12	120.25 (13)
C6—C5—H5A	120.5	C14—C13—H13A	119.9
N1—C6—C5	124.71 (11)	C12—C13—H13A	119.9
N1—C6—C1	115.57 (10)	C13—C14—C15	119.76 (14)
C5—C6—C1	119.71 (12)	C13—C14—H14A	120.1
N1—C7—S2	125.63 (10)	C15—C14—H14A	120.1
N1—C7—S1	116.71 (10)	C14—C15—C10	120.42 (13)
S2—C7—S1	117.63 (7)	C14—C15—H15A	119.8
C9—C8—S2	109.28 (9)	C10—C15—H15A	119.8
C9—C8—H8A	109.8

C7—S1—C1—C2	179.53 (13)	C8—S2—C7—S1	−172.57 (8)
C7—S1—C1—C6	0.04 (9)	C1—S1—C7—N1	0.00 (11)
C6—C1—C2—C3	0.86 (19)	C1—S1—C7—S2	177.93 (8)
S1—C1—C2—C3	−178.59 (11)	C7—S2—C8—C9	175.74 (9)
C1—C2—C3—C4	−1.0 (2)	S2—C8—C9—O1	−0.42 (16)
C2—C3—C4—C5	0.2 (2)	S2—C8—C9—C10	179.05 (10)
C3—C4—C5—C6	0.7 (2)	O1—C9—C10—C11	−0.4 (2)
C7—N1—C6—C5	−179.59 (12)	C8—C9—C10—C11	−179.87 (12)
C7—N1—C6—C1	0.07 (15)	O1—C9—C10—C15	178.67 (13)
C4—C5—C6—N1	178.80 (12)	C8—C9—C10—C15	−0.79 (18)
C4—C5—C6—C1	−0.84 (19)	C15—C10—C11—C12	−0.7 (2)
C2—C1—C6—N1	−179.62 (11)	C9—C10—C11—C12	178.35 (13)
S1—C1—C6—N1	−0.07 (13)	C10—C11—C12—C13	−0.6 (2)
C2—C1—C6—C5	0.06 (19)	C11—C12—C13—C14	1.5 (2)
S1—C1—C6—C5	179.61 (10)	C12—C13—C14—C15	−1.0 (2)
C6—N1—C7—S2	−177.78 (9)	C13—C14—C15—C10	−0.3 (2)
C6—N1—C7—S1	−0.04 (14)	C11—C10—C15—C14	1.2 (2)
C8—S2—C7—N1	5.15 (13)	C9—C10—C15—C14	−177.84 (13)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C2—H2A···O1ⁱ	0.93	2.51	3.2299 (17)	135

Symmetry code: (i) −x, y+1/2, −z+3/2.

Experimental details

Crystal data
Chemical formula	C₁₅H₁₁NOS₂
M_r	285.37
Crystal system, space group	Orthorhombic, P2₁2₁2₁
Temperature (K)	295
a, b, c (Å)	5.1060 (1), 14.6220 (3), 17.3920 (4)
V (Å³)	1298.49 (5)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.40
Crystal size (mm)	0.45 × 0.32 × 0.17

Data collection
Diffractometer	Bruker SMART APEXII CCD area-detector diffractometer
Absorption correction	Multi-scan (SADABS; Bruker, 2005)
T_min, T_max	0.841, 0.935
No. of measured, independent and observed [I > 2σ(I)] reflections	14309, 3734, 3576
R_int	0.024
(sin θ/λ)_max (Å⁻¹)	0.703

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.027, 0.068, 1.07
No. of reflections	3734
No. of parameters	172
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.31, −0.16
Absolute structure	Flack (1983), 1550 Friedel pairs
Absolute structure parameter	0.01 (5)

Computer programs: APEX2 (Bruker, 2005), SAINT (Bruker, 2005), SIR2004 (Burla et al., 2004), SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2009).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C2—H2A···O1ⁱ	0.93	2.51	3.2299 (17)	134.6

Symmetry code: (i) −x, y+1/2, −z+3/2.

Footnotes

‡Additional corresponding author, e-mail: zsrkk@yahoo.com. Thomson Reuters ResearcherID: A-5471-2009.

Acknowledgements

We thank the University of Isfahan and the University of Malaya for supporting this work.

References

Antane, S., Bernotas, R., Li, Y., David, M. R. & Yan, Y. (2004). Synth. Commun. 34, 2443–2449. Web of Science CrossRef CAS Google Scholar
Bruker (2005). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Burla, M. C., Caliandro, R., Carrozzini, B., Cascarano, G. L., De Caro, L., Giacovazzo, C. & Polidori, G. (2004). J. Appl. Cryst. 37, 258–264. 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
Fuju, M., Nakamura, K., Mekata, H., Oka, S. & Ohno, A. (1988). Bull. Chem. Soc. Jpn, 61, 495–500. Google Scholar
Grossert, J. S., Dubey, P. K., Gill, G. H., Cameron, T. S. & Gardner, P. A. (1984). Can. J. Chem. 62, 798–807. CrossRef CAS Web of Science Google Scholar
Marco, J. L., Fernandez, N., Khira, I., Fernandez, P. & Romero, A. J. (1995). J. Org. Chem. 60, 6678–6679. CSD CrossRef CAS Web of Science Google Scholar
Ni, C., Li, Y. & Hu, J. (2006). J. Org. Chem. 71, 6829–6833. Web of Science CrossRef PubMed CAS Google Scholar
Oishi, Y., Watanabe, T., Kusa, K., Kazama, M. & Koniya, K. (1988). Jpn Patent JP63 243 067, 212359. Google Scholar
Padmavathi, V., Thriveni, T., Sudhakar Reddy, G. & Deepti, D. (2008). Eur. J. Med. Chem. 43, 917–924. Web of Science CrossRef PubMed 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