1-(3-Ethyl­phen­yl)-4,6-dimethyl-2-oxo-1,2-dihydro­pyridine-3-carbonitrile

Al-Said, M.S.; Ghorab, M.M.; Ghabbour, H.A.; Arshad, S.; Fun, H.-K.

doi:10.1107/S1600536812019927

organic compounds

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ISSN: 2056-9890

Volume 68| Part 6| June 2012| Page o1679

doi:10.1107/S1600536812019927

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1-(3-Ethylphenyl)-4,6-dimethyl-2-oxo-1,2-dihydropyridine-3-carbonitrile

Mansour S. Al-Said,^a Mostafa M. Ghorab,^a Hazem A. Ghabbour,^b Suhana Arshad ^c and Hoong-Kun Fun ^c ^*‡

^aMedicinal, Aromatic and Poisonous Plants Research Center (MAPPRC), College of Pharmacy, King Saud University, PO Box 2457, Riyadh 11451, Saudi Arabia, ^bDepartment of Pharmaceutical Chemistry, College of Pharmacy, King Saud University, PO Box 2457, Riyadh 11451, Saudi Arabia, and ^cX-ray Crystallography Unit, School of Physics, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia
^*Correspondence e-mail: hkfun@usm.my

(Received 2 May 2012; accepted 3 May 2012; online 12 May 2012)

In the title compound, C₁₆H₁₆N₂O, the essentially planar 1,2-dihydropyridine ring [maximum deviation = 0.021 (1) Å] makes a dihedral angle of 85.33 (8)° with the benzene ring. In the crystal, molecules are linked into a chain along the b axis via C—H⋯O interactions.

Related literature

For the biological activities and applications of 2-pyridone derivatives, see: Abadi et al. (2009 ); Cheney et al. (2007 ); Aqui & Vonderheide (2008 ); Ambrosini et al. (1997 ); Murata et al. (2001 ); Ghorab et al. (2009 , 2010 ); Al-Said et al. (2010 ). For related structures, see: Lynch & McClenaghan (2002 ); Elgemeie & Jones (2004 ).

Experimental

Crystal data

C₁₆H₁₆N₂O
M_r = 252.31
Monoclinic, P 2₁ /c
a = 8.3834 (3) Å
b = 7.1852 (2) Å
c = 23.5264 (8) Å
β = 93.203 (3)°
V = 1414.93 (8) Å³
Z = 4
Cu Kα radiation
μ = 0.59 mm⁻¹
T = 296 K
0.93 × 0.46 × 0.07 mm

Data collection

Bruker APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2009 ) T_min = 0.609, T_max = 0.960
9742 measured reflections
2638 independent reflections
1938 reflections with I > 2σ(I)
R_int = 0.032

Refinement

R[F² > 2σ(F²)] = 0.047
wR(F²) = 0.161
S = 1.09
2638 reflections
170 parameters
H-atom parameters constrained
Δρ_max = 0.30 e Å⁻³
Δρ_min = −0.18 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C4—H4A⋯O1ⁱ	0.93	2.32	3.2105 (18)	161
Symmetry code: (i) x, y+1, z.

Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ); program(s) used to refine structure: SHELXTL; 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/S1600536812019927/is5134sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536812019927/is5134Isup2.hkl

Supporting information file. DOI: 10.1107/S1600536812019927/is5134Isup3.cml

checkCIF report

Comment top

It was reported that compounds containing the 2-pyridone moiety was proven to possess several biological properties, especially anticancer activity (Abadi et al., 2009; Cheney et al., 2007; Aqui & Vonderheide, 2008; Ambrosini et al., 1997; Murata et al., 2001). Compounds containing heteroaromatic rings frequently play an important role as scaffolds of bioactive substances. It is well known that pyridone and its derivatives are among the most popular N-heteroaromatic compounds integrated into the structures of many pharmaceutical compounds and their structural units occur in various molecules exhibiting diverse biological activities (Abadi et al., 2009). Based on the above information and as a continuation of our previous work on anticancer agents (Ghorab et al., 2009; Al-Said et al., 2010; Ghorab et al., 2010), we report the synthesis of a novel 2-pyridone derivative which is expected to exhibit anticancer activity.

In the title compound (Fig. 1), the 1,2-dihydropyridine ring (N1/C1–C5) is essentially planar with a maximum deviation of 0.021 (1) Å at atom N1 and almost perpendicular with the benzene ring (C6–C11) with a dihedral angle of 85.33 (8)°. Bond lengths and angles are within the normal ranges and are comparable to those in the related structures (Lynch & McClenaghan, 2002; Elgemeie & Jones, 2004). The crystal structure is shown in Fig. 2. The molecules are linked into a one-dimensional chain along the b-axis via C4—H4A···O1 interactions (Table 1).

Related literature top

For the biological activities and applications of 2-pyridone derivatives, see: Abadi et al. (2009); Cheney et al. (2007); Aqui & Vonderheide (2008); Ambrosini et al. (1997); Murata et al. (2001); Ghorab et al. (2009); Al-Said et al. (2010); Ghorab et al. (2010). For related structures, see: Lynch & McClenaghan (2002); Elgemeie & Jones (2004).

Experimental top

A mixture of 2-cyano-N-(3-ethylphenyl)acetamide (1.88 g, 0.01 mol) and acetylacetone (1.00 g, 0.01 mol) in absolute ethanol (50 ml) containing piperidine (0.5 ml) were refluxed for 5 h. The reaction mixture was triturated with ethanol and the solid obtained was recrystallized from ethanol to give the title compound. A single-crystal suitable for an X-ray structural analysis was obtained by slow evaporation from an ethanol solution at room temperature.

Computing details top

Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT (Bruker, 2009); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); 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 compound, showing 30% probability displacement ellipsoids and the atom-numbering scheme.
	Fig. 2. A crystal packing diagram of the title compound viewed along the c axis. For the sake of clarity, H atoms not involved in the intermolecular interactions (dashed lines) have been omitted.

1-(3-Ethylphenyl)-4,6-dimethyl-2-oxo-1,2-dihydropyridine-3-carbonitrile top

Crystal data top

C₁₆H₁₆N₂O	F(000) = 536
M_r = 252.31	D_x = 1.184 Mg m⁻³
Monoclinic, P2₁/c	Cu Kα radiation, λ = 1.54178 Å
Hall symbol: -P 2ybc	Cell parameters from 1728 reflections
a = 8.3834 (3) Å	θ = 3.8–62.6°
b = 7.1852 (2) Å	µ = 0.59 mm⁻¹
c = 23.5264 (8) Å	T = 296 K
β = 93.203 (3)°	Plate, colorless
V = 1414.93 (8) Å³	0.93 × 0.46 × 0.07 mm
Z = 4

Data collection top

Bruker APEXII CCD diffractometer	2638 independent reflections
Radiation source: fine-focus sealed tube	1938 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.032
ϕ and ω scans	θ_max = 69.8°, θ_min = 3.8°
Absorption correction: multi-scan (SADABS; Bruker, 2009)	h = −10→10
T_min = 0.609, T_max = 0.960	k = −6→8
9742 measured reflections	l = −28→28

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)] = 0.047	H-atom parameters constrained
wR(F²) = 0.161	w = 1/[σ²(F_o²) + (0.0972P)² + 0.0312P] where P = (F_o² + 2F_c²)/3
S = 1.09	(Δ/σ)_max < 0.001
2638 reflections	Δρ_max = 0.30 e Å⁻³
170 parameters	Δρ_min = −0.18 e Å⁻³
0 restraints	Extinction correction: SHELXL, Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.0026 (7)

Crystal data top

C₁₆H₁₆N₂O	V = 1414.93 (8) Å³
M_r = 252.31	Z = 4
Monoclinic, P2₁/c	Cu Kα radiation
a = 8.3834 (3) Å	µ = 0.59 mm⁻¹
b = 7.1852 (2) Å	T = 296 K
c = 23.5264 (8) Å	0.93 × 0.46 × 0.07 mm
β = 93.203 (3)°

Data collection top

Bruker APEXII CCD diffractometer	2638 independent reflections
Absorption correction: multi-scan (SADABS; Bruker, 2009)	1938 reflections with I > 2σ(I)
T_min = 0.609, T_max = 0.960	R_int = 0.032
9742 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.047	0 restraints
wR(F²) = 0.161	H-atom parameters constrained
S = 1.09	Δρ_max = 0.30 e Å⁻³
2638 reflections	Δρ_min = −0.18 e Å⁻³
170 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
O1	0.51182 (17)	−0.19353 (15)	0.40553 (6)	0.0771 (4)
N1	0.43401 (15)	0.09675 (17)	0.37682 (6)	0.0565 (4)
N2	0.8174 (2)	−0.1541 (2)	0.51433 (8)	0.0818 (5)
C1	0.52879 (18)	−0.0253 (2)	0.41097 (7)	0.0567 (4)
C2	0.64093 (18)	0.0642 (2)	0.45059 (7)	0.0596 (3)
C3	0.65232 (18)	0.2536 (2)	0.45604 (7)	0.0574 (4)
C4	0.54774 (19)	0.3644 (2)	0.42144 (8)	0.0614 (4)
H4A	0.5523	0.4932	0.4250	0.074*
C5	0.44005 (19)	0.2869 (2)	0.38292 (7)	0.0580 (4)
C6	0.32547 (19)	0.0076 (2)	0.33530 (7)	0.0599 (4)
C7	0.1715 (2)	−0.0320 (2)	0.34863 (8)	0.0687 (5)
H7A	0.1361	0.0037	0.3838	0.082*
C8	0.0682 (2)	−0.1252 (3)	0.30994 (9)	0.0756 (5)
C9	0.1242 (3)	−0.1759 (3)	0.25855 (9)	0.0826 (6)
H9A	0.0571	−0.2395	0.2324	0.099*
C11	0.3787 (2)	−0.0421 (3)	0.28313 (8)	0.0763 (5)
H11A	0.4822	−0.0133	0.2739	0.092*
C12	−0.0998 (3)	−0.1725 (4)	0.32586 (12)	0.1040 (8)
H12A	−0.1475	−0.0635	0.3423	0.125*
H12B	−0.1637	−0.2053	0.2917	0.125*
C13	−0.1029 (3)	−0.3299 (4)	0.36728 (13)	0.1134 (9)
H13A	−0.2115	−0.3566	0.3754	0.170*
H13B	−0.0437	−0.2960	0.4018	0.170*
H13C	−0.0556	−0.4381	0.3512	0.170*
C14	0.73956 (19)	−0.0576 (2)	0.48568 (7)	0.0596 (3)
C15	0.7695 (2)	0.3428 (2)	0.49802 (9)	0.0739 (5)
H15A	0.8759	0.3053	0.4901	0.111*
H15B	0.7470	0.3047	0.5358	0.111*
H15C	0.7607	0.4757	0.4950	0.111*
C16	0.3267 (2)	0.4026 (3)	0.34699 (9)	0.0788 (6)
H16A	0.3524	0.5319	0.3524	0.118*
H16B	0.2196	0.3803	0.3578	0.118*
H16C	0.3350	0.3703	0.3077	0.118*
C10	0.2776 (3)	−0.1347 (3)	0.24493 (9)	0.0876 (6)
H10A	0.3129	−0.1697	0.2097	0.105*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1	0.0885 (9)	0.0349 (6)	0.1054 (10)	−0.0021 (5)	−0.0179 (7)	−0.0017 (5)
N1	0.0590 (7)	0.0398 (7)	0.0703 (8)	−0.0013 (5)	0.0004 (6)	0.0012 (5)
N2	0.0869 (11)	0.0633 (10)	0.0934 (12)	0.0139 (8)	−0.0113 (9)	0.0020 (7)
C1	0.0609 (8)	0.0358 (8)	0.0735 (10)	0.0006 (6)	0.0040 (7)	0.0010 (6)
C2	0.0608 (6)	0.0431 (6)	0.0747 (7)	0.0014 (5)	0.0019 (5)	−0.0009 (5)
C3	0.0564 (8)	0.0408 (8)	0.0754 (10)	−0.0031 (6)	0.0078 (7)	−0.0021 (6)
C4	0.0657 (9)	0.0343 (7)	0.0842 (11)	−0.0015 (6)	0.0040 (8)	−0.0001 (7)
C5	0.0611 (9)	0.0393 (8)	0.0740 (10)	0.0006 (6)	0.0066 (7)	0.0047 (6)
C6	0.0643 (9)	0.0441 (8)	0.0708 (10)	0.0003 (7)	−0.0015 (7)	0.0005 (6)
C7	0.0668 (9)	0.0638 (11)	0.0751 (11)	−0.0024 (8)	0.0006 (8)	−0.0010 (8)
C8	0.0698 (10)	0.0683 (11)	0.0872 (13)	−0.0069 (9)	−0.0094 (9)	0.0029 (9)
C9	0.0881 (14)	0.0756 (13)	0.0816 (13)	−0.0042 (9)	−0.0162 (11)	−0.0080 (9)
C11	0.0761 (11)	0.0758 (13)	0.0772 (12)	−0.0043 (9)	0.0074 (9)	−0.0066 (9)
C12	0.0726 (13)	0.117 (2)	0.120 (2)	−0.0191 (12)	−0.0096 (12)	−0.0005 (15)
C13	0.0886 (15)	0.143 (3)	0.1091 (19)	−0.0278 (15)	0.0121 (14)	−0.0044 (16)
C14	0.0608 (6)	0.0431 (6)	0.0747 (7)	0.0014 (5)	0.0019 (5)	−0.0009 (5)
C15	0.0712 (11)	0.0527 (10)	0.0963 (14)	−0.0067 (8)	−0.0075 (9)	−0.0088 (8)
C16	0.0884 (12)	0.0489 (10)	0.0970 (13)	0.0083 (8)	−0.0137 (10)	0.0082 (8)
C10	0.1033 (16)	0.0863 (14)	0.0730 (12)	0.0018 (12)	0.0032 (11)	−0.0142 (10)

Geometric parameters (Å, º) top

O1—C1	1.2233 (18)	C8—C12	1.516 (3)
N1—C5	1.374 (2)	C9—C10	1.375 (3)
N1—C1	1.4050 (19)	C9—H9A	0.9300
N1—C6	1.447 (2)	C11—C10	1.373 (3)
N2—C14	1.145 (2)	C11—H11A	0.9300
C1—C2	1.438 (2)	C12—C13	1.494 (4)
C2—C3	1.369 (2)	C12—H12A	0.9700
C2—C14	1.434 (2)	C12—H12B	0.9700
C3—C4	1.409 (2)	C13—H13A	0.9600
C3—C15	1.498 (2)	C13—H13B	0.9600
C4—C5	1.362 (2)	C13—H13C	0.9600
C4—H4A	0.9300	C15—H15A	0.9600
C5—C16	1.490 (2)	C15—H15B	0.9600
C6—C7	1.375 (2)	C15—H15C	0.9600
C6—C11	1.377 (3)	C16—H16A	0.9600
C7—C8	1.393 (3)	C16—H16B	0.9600
C7—H7A	0.9300	C16—H16C	0.9600
C8—C9	1.371 (3)	C10—H10A	0.9300

C5—N1—C1	122.98 (13)	C10—C11—H11A	120.3
C5—N1—C6	121.91 (13)	C6—C11—H11A	120.3
C1—N1—C6	115.10 (12)	C13—C12—C8	112.4 (2)
O1—C1—N1	119.87 (14)	C13—C12—H12A	109.1
O1—C1—C2	125.29 (14)	C8—C12—H12A	109.1
N1—C1—C2	114.83 (13)	C13—C12—H12B	109.1
C3—C2—C14	121.17 (14)	C8—C12—H12B	109.1
C3—C2—C1	123.00 (14)	H12A—C12—H12B	107.9
C14—C2—C1	115.82 (13)	C12—C13—H13A	109.5
C2—C3—C4	117.99 (14)	C12—C13—H13B	109.5
C2—C3—C15	121.81 (15)	H13A—C13—H13B	109.5
C4—C3—C15	120.19 (14)	C12—C13—H13C	109.5
C5—C4—C3	121.42 (14)	H13A—C13—H13C	109.5
C5—C4—H4A	119.3	H13B—C13—H13C	109.5
C3—C4—H4A	119.3	N2—C14—C2	179.11 (19)
C4—C5—N1	119.66 (14)	C3—C15—H15A	109.5
C4—C5—C16	121.84 (15)	C3—C15—H15B	109.5
N1—C5—C16	118.50 (15)	H15A—C15—H15B	109.5
C7—C6—C11	120.32 (16)	C3—C15—H15C	109.5
C7—C6—N1	120.05 (16)	H15A—C15—H15C	109.5
C11—C6—N1	119.60 (15)	H15B—C15—H15C	109.5
C6—C7—C8	120.54 (18)	C5—C16—H16A	109.5
C6—C7—H7A	119.7	C5—C16—H16B	109.5
C8—C7—H7A	119.7	H16A—C16—H16B	109.5
C9—C8—C7	118.25 (18)	C5—C16—H16C	109.5
C9—C8—C12	121.81 (19)	H16A—C16—H16C	109.5
C7—C8—C12	119.9 (2)	H16B—C16—H16C	109.5
C8—C9—C10	121.29 (19)	C11—C10—C9	120.2 (2)
C8—C9—H9A	119.4	C11—C10—H10A	119.9
C10—C9—H9A	119.4	C9—C10—H10A	119.9
C10—C11—C6	119.37 (18)

C5—N1—C1—O1	176.08 (15)	C1—N1—C5—C16	−176.04 (16)
C6—N1—C1—O1	−2.4 (2)	C6—N1—C5—C16	2.3 (2)
C5—N1—C1—C2	−3.9 (2)	C5—N1—C6—C7	−85.9 (2)
C6—N1—C1—C2	177.62 (13)	C1—N1—C6—C7	92.63 (18)
O1—C1—C2—C3	−178.23 (16)	C5—N1—C6—C11	96.09 (19)
N1—C1—C2—C3	1.7 (2)	C1—N1—C6—C11	−85.41 (19)
O1—C1—C2—C14	0.4 (3)	C11—C6—C7—C8	0.9 (3)
N1—C1—C2—C14	−179.68 (14)	N1—C6—C7—C8	−177.12 (16)
C14—C2—C3—C4	−177.87 (15)	C6—C7—C8—C9	0.0 (3)
C1—C2—C3—C4	0.6 (2)	C6—C7—C8—C12	178.37 (19)
C14—C2—C3—C15	1.0 (3)	C7—C8—C9—C10	−0.7 (3)
C1—C2—C3—C15	179.52 (16)	C12—C8—C9—C10	−179.0 (2)
C2—C3—C4—C5	−1.1 (2)	C7—C6—C11—C10	−1.2 (3)
C15—C3—C4—C5	179.98 (16)	N1—C6—C11—C10	176.86 (17)
C3—C4—C5—N1	−0.9 (2)	C9—C8—C12—C13	104.2 (3)
C3—C4—C5—C16	178.71 (16)	C7—C8—C12—C13	−74.1 (3)
C1—N1—C5—C4	3.6 (2)	C6—C11—C10—C9	0.5 (3)
C6—N1—C5—C4	−178.01 (15)	C8—C9—C10—C11	0.4 (3)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C4—H4A···O1ⁱ	0.93	2.32	3.2105 (18)	161

Symmetry code: (i) x, y+1, z.

Experimental details

Crystal data
Chemical formula	C₁₆H₁₆N₂O
M_r	252.31
Crystal system, space group	Monoclinic, P2₁/c
Temperature (K)	296
a, b, c (Å)	8.3834 (3), 7.1852 (2), 23.5264 (8)
β (°)	93.203 (3)
V (Å³)	1414.93 (8)
Z	4
Radiation type	Cu Kα
µ (mm⁻¹)	0.59
Crystal size (mm)	0.93 × 0.46 × 0.07

Data collection
Diffractometer	Bruker APEXII CCD diffractometer
Absorption correction	Multi-scan (SADABS; Bruker, 2009)
T_min, T_max	0.609, 0.960
No. of measured, independent and observed [I > 2σ(I)] reflections	9742, 2638, 1938
R_int	0.032
(sin θ/λ)_max (Å⁻¹)	0.609

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.047, 0.161, 1.09
No. of reflections	2638
No. of parameters	170
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.30, −0.18

Computer programs: APEX2 (Bruker, 2009), SAINT (Bruker, 2009), 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
C4—H4A···O1ⁱ	0.93	2.32	3.2105 (18)	161

Symmetry code: (i) x, y+1, z.

Footnotes

‡Thomson Reuters ResearcherID: A-3561-2009.

Acknowledgements

The authors are grateful for the sponsorship of the Research Center, College of Pharmacy and the Deanship of Scientific Research, King Saud University, Riyadh, Saudi Arabia. HKF and SA thank Universiti Sains Malaysia (USM) for the Research University Grant (No. 1001/PFIZIK/811160). SA thanks the Malaysian Government and USM for the award of Academic Staff Training Scheme (ASTS).

References

Abadi, A. H., Ibrahim, T. M., Abouzid, K. M., Lehmann, J., Tinsley, H. N., Gary, B. D. & Piazza, G. A. (2009). Bioorg. Med. Chem. 17, 5974–5982. Web of Science CrossRef PubMed CAS Google Scholar
Al-Said, M. S., Ghorab, M. M., Alqasoumi, S. I., El-Hossary, E. M. & Noaman, E. (2010). Eur. J. Med. Chem. 45, 3011–3018. Web of Science CAS PubMed Google Scholar
Ambrosini, G., Adida, C. & Altieri, D. C. (1997). Nat. Med. 3, 917–921. CrossRef CAS PubMed Web of Science Google Scholar
Aqui, N. A. & Vonderheide, R. H. (2008). Cancer Biol. Ther. 7, 1888–1889. Web of Science CrossRef PubMed Google Scholar
Bruker (2009). SADABS, APEX2 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Cheney, I. W., Yan, S., Appleby, T., Walker, H., Vo, T., Yao, N., Hamatake, R., Hong, Z. & Wu, J. Z. (2007). Bioorg. Med. Chem. Lett. 17, 1679–1683. Web of Science CrossRef PubMed CAS Google Scholar
Elgemeie, G. H. & Jones, P. G. (2004). Acta Cryst. E60, o2107–o2109. Web of Science CSD CrossRef IUCr Journals Google Scholar
Ghorab, M. M., Ragab, F. A., Alqasoumi, S. I., Alafeefy, A. M. & Aboulmagd, S. A. (2010). Eur. J. Med. Chem. 45, 171–178. Web of Science CrossRef PubMed CAS Google Scholar
Ghorab, M. M., Ragab, F. A. & Hamed, M. M. (2009). Eur. J. Med. Chem. 44, 4211–4217. Web of Science CrossRef PubMed CAS Google Scholar
Lynch, D. E. & McClenaghan, I. (2002). Acta Cryst. E58, o680–o681. Web of Science CSD CrossRef IUCr Journals Google Scholar
Murata, T., Sugatani, T., Shimizu, K., Manganiello, V. & Tagawa, T. (2001). Anticancer Drugs, 12, 79–83. 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