4-(3,5-Di­meth­oxy­phen­yl)-6-(2-meth­oxy­phen­yl)pyrimidin-2-amine

Koh, D.; Lee, J.H.

doi:10.1107/S2414314618007964

organic compounds

IUCrDATA

ISSN: 2414-3146

Volume 3| Part 6| June 2018| x180796

https://doi.org/10.1107/S2414314618007964

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4-(3,5-Dimethoxyphenyl)-6-(2-methoxyphenyl)pyrimidin-2-amine

Dongsoo Koh ^a ^* and Ji Hye Lee ^a

^aDepartment of Applied Chemistry, Dongduk Women's University, Seoul 136-714, Republic of Korea
^*Correspondence e-mail: dskoh@dongduk.ac.kr

Edited by J. Simpson, University of Otago, New Zealand (Received 25 May 2018; accepted 30 May 2018; online 5 June 2018)

In the title molecule, C₁₉H₁₉N₃O₃, the 2-methoxyphenyl and 3,5-dimethoxyphenyl rings are attached at the 4- and 6-positions, respectively, of the central 2-aminopyrimidine ring. The dihedral angles between the planes of the benzene rings and that of the 2-aminopyrimidine ring are 17.31 (9) and 44.39 (6)°, respectively. In the crystal, pairs of N—H⋯N hydrogen bonds form inversion dimers enclosing R₂²(8) rings. Pairs of N—H⋯O hydrogen bonds link the dimers into chains along [010].

Keywords: crystal structure; 2-aminopyrimidine; hydrogen bonds; intermolecular dimers.

CCDC reference: 1846182

Structure description

2-Aminopyrimidine pharmacophores have shown a broad spectrum of biological activities including use against Parkinson's disease (Robinson et al., 2016 ) and displaying anti-bacterial (Nagarajan et al., 2014 ), anti-platelet (Giridhar et al., 2012 ), antidiabetic (Singh et al., 2011 ) and antitumor properties (Lee et al., 2011 ). The title 2-aminopyrimidine compound was synthesized in a continuation of our research program to expand the use of novel synthetic chalcones (Lee et al. 2016 ), and its crystal structure was determined and is reported here.

The molecular structure of the title compound is shown in Fig. 1. The central 2-aminopyrimidine ring contains two benzene rings at the C4 and C6 positions respectively. The dihedral angles between central 2-aminopyrimidine ring and the C5–C10 and C12–C17 benzene rings are 17.31 (9) and 44.39 (6)°, respectively. All three methoxy groups on the benzene rings are slightly twisted from the ring plane [C17—C16—O3—C19 = −4.9 (2), C15—C14—O2—C18 = −4.5 (2) and C7—C6—O1—C11 = 3.7 (2)°].

Figure 1
The molecular structure of the title compound, showing the atom-labelling scheme with displacement ellipsoids drawn at the 30% probability level.

In the crystal, pairs of N3—H3B⋯N2 hydrogen bonds form inversion dimers that enclose R₂²(8) rings. These dimers are linked into chains along the b-axis direction by pairs of N3—H3A⋯O3 hydrogen bonds (Table 1, Fig. 2).

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N3—H3B⋯N2ⁱ	0.87	2.28	3.1374 (19)	167
N3—H3A⋯O3ⁱⁱ	0.87	2.39	3.2545 (17)	175
Symmetry codes: (i) -x+3, -y+1, -z+2; (ii) x, y+1, z.

Figure 2
Part of the crystal structure with intermolecular hydrogen bonds shown as dashed lines. For clarity only those H atoms involved in hydrogen bonding are shown.

Some examples of other 2-aminopyrimidine structures have also been published recently (Sangeetha et al., 2016 ; Thanigaimani et al., 2012 ).

Synthesis and crystallization

A synthetic scheme is shown in Fig. 3. The chalcone (E)-1-(3,5-dimethoxyphenyl)-3-(2-methoxyphenyl)prop-2-en-1-one was prepared as a starting material by a previously reported method (Koh et al. 2016 ). 2-Amino pyrimidine was obtained by a cyclization reaction of this chalcone with guanidine hydrogen chloride in basic solution. To an ethanol solution of 3,5-dimethoxyacetophenone (I) and 2-methoxybenzaldehyde (II) an excess amount of 50% aqueous KOH was added and the mixture was stirred at room temperature for 20 h. After completion of reaction, the reaction mixture was poured into 6M HCl in an ice-bath to give a precipitate of the chalcone (III). The solid was filtered and washed with ethanol and was used for the next reaction without further purification. The chalcone (III, 1 eq.) and the guanidine HCl salt (1.5 eq.) were dissolved in a DMF solution to which was added solid K₂CO₃ (3 eq.). The reaction mixture was refluxed for 2 h and cooled to room temperature. The reaction mixture was then poured into 3M HCl in an ice bath to give a precipitate of the title 2-aminopyrimidine compound, which was purified by recrystallization from ethanol.

Figure 3
Synthetic scheme for the preparation of the title compound.

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2.

Table 2
Experimental details

Crystal data
Chemical formula	C₁₉H₁₉N₃O₃
M_r	337.37
Crystal system, space group	Triclinic, P $[\overline{1}]$
Temperature (K)	223
a, b, c (Å)	7.5867 (7), 10.2680 (7), 11.4684 (8)
α, β, γ (°)	95.592 (4), 102.147 (4), 109.987 (3)
V (Å³)	806.71 (11)
Z	2
Radiation type	Mo Kα
μ (mm⁻¹)	0.10
Crystal size (mm)	0.18 × 0.10 × 0.06

Data collection
Diffractometer	Bruker PHOTON 100 CMOS
Absorption correction	Multi-scan (SADABS; Bruker, 2012 )
T_min, T_max	0.690, 0.746
No. of measured, independent and observed [I > 2σ(I)] reflections	26671, 4065, 2736
R_int	0.063
(sin θ/λ)_max (Å⁻¹)	0.671

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.046, 0.112, 1.02
No. of reflections	4065
No. of parameters	229
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.24, −0.21
Computer programs: APEX2 and SAINT (Bruker, 2012), SHELXS and SHELXTL (Sheldrick, 2008 ), SHELXL2014 (Sheldrick, 2015 ) and publCIF (Westrip, 2010 ).

Structural data

CCDC reference: 1846182

Crystal structure: contains datablock I. DOI: https://doi.org/10.1107/S2414314618007964/sj4180sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2414314618007964/sj4180Isup2.hkl

Supporting information file. DOI: https://doi.org/10.1107/S2414314618007964/sj4180Isup3.cml

checkCIF report

Computing details top

Data collection: APEX2 (Bruker, 2012); cell refinement: SAINT (Bruker, 2012); data reduction: SAINT (Bruker, 2012); program(s) used to solve structure: SHELXS (Sheldrick, 2008); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008) and publCIF (Westrip, 2010).

4-(3,5-Dimethoxyphenyl)-6-(2-methoxyphenyl)pyrimidin-2-amine top

Crystal data top

C₁₉H₁₉N₃O₃	Z = 2
M_r = 337.37	F(000) = 356
Triclinic, P1	D_x = 1.389 Mg m⁻³
a = 7.5867 (7) Å	Mo Kα radiation, λ = 0.71073 Å
b = 10.2680 (7) Å	Cell parameters from 5933 reflections
c = 11.4684 (8) Å	θ = 2.6–27.9°
α = 95.592 (4)°	µ = 0.10 mm⁻¹
β = 102.147 (4)°	T = 223 K
γ = 109.987 (3)°	Block, yellow
V = 806.71 (11) Å³	0.18 × 0.10 × 0.06 mm

Data collection top

Bruker PHOTON 100 CMOS diffractometer	2736 reflections with I > 2σ(I)
φ and ω scans	R_int = 0.063
Absorption correction: multi-scan (SADABS; Bruker, 2012)	θ_max = 28.5°, θ_min = 2.9°
T_min = 0.690, T_max = 0.746	h = −10→10
26671 measured reflections	k = −13→13
4065 independent reflections	l = −15→15

Refinement top

Refinement on F²	0 restraints
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F² > 2σ(F²)] = 0.046	H-atom parameters constrained
wR(F²) = 0.112	w = 1/[σ²(F_o²) + (0.0434P)² + 0.2728P] where P = (F_o² + 2F_c²)/3
S = 1.02	(Δ/σ)_max < 0.001
4065 reflections	Δρ_max = 0.24 e Å⁻³
229 parameters	Δρ_min = −0.21 e Å⁻³

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
C1	1.2100 (2)	0.51141 (15)	0.91277 (13)	0.0264 (3)
N1	1.04986 (18)	0.52945 (13)	0.85350 (11)	0.0277 (3)
C2	0.9093 (2)	0.41773 (15)	0.77721 (13)	0.0240 (3)
C3	0.9345 (2)	0.29009 (16)	0.75753 (14)	0.0266 (3)
H3	0.8409	0.2128	0.7001	0.032*
C4	1.1029 (2)	0.28096 (15)	0.82566 (13)	0.0251 (3)
N2	1.24219 (18)	0.38985 (13)	0.90484 (11)	0.0277 (3)
N3	1.3510 (2)	0.62546 (13)	0.98728 (12)	0.0346 (3)
H3A	1.3357	0.7058	0.9951	0.052*
H3B	1.4575	0.6189	1.0276	0.052*
C5	0.7267 (2)	0.44012 (15)	0.72488 (13)	0.0250 (3)
C6	0.5714 (2)	0.34812 (16)	0.62920 (14)	0.0282 (3)
C7	0.4022 (2)	0.37506 (19)	0.59430 (17)	0.0387 (4)
H7	0.2980	0.3120	0.5314	0.046*
C8	0.3857 (3)	0.49308 (19)	0.65090 (18)	0.0425 (4)
H8	0.2704	0.5100	0.6267	0.051*
C9	0.5371 (3)	0.58643 (18)	0.74266 (17)	0.0382 (4)
H9	0.5269	0.6681	0.7803	0.046*
C10	0.7041 (2)	0.55922 (17)	0.77906 (15)	0.0311 (4)
H10	0.8063	0.6230	0.8426	0.037*
O1	0.59265 (17)	0.23350 (12)	0.57163 (11)	0.0385 (3)
C11	0.4395 (3)	0.14655 (19)	0.46928 (17)	0.0456 (5)
H11A	0.3258	0.0969	0.4961	0.068*
H11B	0.4809	0.0788	0.4292	0.068*
H11C	0.4079	0.2049	0.4130	0.068*
C12	1.1292 (2)	0.14340 (15)	0.81773 (14)	0.0253 (3)
C13	1.0781 (2)	0.05546 (16)	0.70723 (14)	0.0269 (3)
H13	1.0340	0.0843	0.6351	0.032*
C14	1.0924 (2)	−0.07653 (16)	0.70354 (14)	0.0259 (3)
C15	1.1509 (2)	−0.12181 (16)	0.80938 (14)	0.0268 (3)
H15	1.1533	−0.2130	0.8067	0.032*
C16	1.2062 (2)	−0.03059 (15)	0.91990 (13)	0.0260 (3)
C17	1.1975 (2)	0.10205 (15)	0.92550 (14)	0.0259 (3)
H17	1.2368	0.1635	1.0004	0.031*
O2	1.04676 (17)	−0.15512 (12)	0.59013 (10)	0.0349 (3)
C18	1.0753 (3)	−0.28546 (17)	0.58342 (16)	0.0358 (4)
H18A	1.2073	−0.2692	0.6273	0.054*
H18B	1.0534	−0.3259	0.4991	0.054*
H18C	0.9848	−0.3500	0.6193	0.054*
O3	1.26833 (17)	−0.08393 (11)	1.01866 (10)	0.0348 (3)
C19	1.3421 (2)	0.00789 (18)	1.13319 (14)	0.0347 (4)
H19A	1.4454	0.0932	1.1287	0.052*
H19B	1.3926	−0.0386	1.1942	0.052*
H19C	1.2386	0.0318	1.1549	0.052*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
C1	0.0294 (8)	0.0204 (8)	0.0277 (8)	0.0096 (6)	0.0031 (6)	0.0041 (6)
N1	0.0291 (7)	0.0207 (7)	0.0298 (7)	0.0095 (5)	0.0008 (5)	0.0032 (5)
C2	0.0261 (8)	0.0215 (7)	0.0248 (7)	0.0094 (6)	0.0052 (6)	0.0062 (6)
C3	0.0278 (8)	0.0191 (7)	0.0279 (8)	0.0082 (6)	−0.0010 (6)	0.0012 (6)
C4	0.0281 (8)	0.0193 (7)	0.0263 (8)	0.0091 (6)	0.0031 (6)	0.0044 (6)
N2	0.0287 (7)	0.0199 (6)	0.0308 (7)	0.0098 (5)	−0.0007 (5)	0.0034 (5)
N3	0.0339 (8)	0.0200 (7)	0.0398 (8)	0.0102 (6)	−0.0078 (6)	−0.0023 (6)
C5	0.0266 (8)	0.0226 (8)	0.0273 (8)	0.0102 (6)	0.0069 (6)	0.0081 (6)
C6	0.0277 (8)	0.0245 (8)	0.0325 (8)	0.0116 (6)	0.0051 (7)	0.0044 (7)
C7	0.0282 (9)	0.0333 (9)	0.0487 (11)	0.0128 (7)	−0.0018 (8)	0.0019 (8)
C8	0.0303 (9)	0.0382 (10)	0.0622 (12)	0.0209 (8)	0.0055 (8)	0.0074 (9)
C9	0.0394 (10)	0.0306 (9)	0.0494 (11)	0.0201 (8)	0.0113 (8)	0.0036 (8)
C10	0.0333 (9)	0.0261 (8)	0.0336 (9)	0.0129 (7)	0.0058 (7)	0.0043 (7)
O1	0.0339 (7)	0.0347 (7)	0.0396 (7)	0.0182 (5)	−0.0071 (5)	−0.0095 (5)
C11	0.0466 (11)	0.0345 (10)	0.0433 (10)	0.0166 (9)	−0.0108 (9)	−0.0062 (8)
C12	0.0223 (7)	0.0183 (7)	0.0320 (8)	0.0073 (6)	0.0007 (6)	0.0039 (6)
C13	0.0273 (8)	0.0232 (8)	0.0279 (8)	0.0102 (6)	0.0001 (6)	0.0061 (6)
C14	0.0236 (8)	0.0228 (8)	0.0276 (8)	0.0089 (6)	0.0006 (6)	0.0003 (6)
C15	0.0264 (8)	0.0189 (7)	0.0334 (8)	0.0103 (6)	0.0022 (6)	0.0032 (6)
C16	0.0248 (8)	0.0226 (8)	0.0289 (8)	0.0092 (6)	0.0021 (6)	0.0068 (6)
C17	0.0242 (7)	0.0215 (8)	0.0274 (8)	0.0078 (6)	−0.0002 (6)	0.0010 (6)
O2	0.0477 (7)	0.0272 (6)	0.0286 (6)	0.0197 (5)	0.0010 (5)	−0.0009 (5)
C18	0.0431 (10)	0.0292 (9)	0.0380 (9)	0.0204 (8)	0.0075 (8)	−0.0001 (7)
O3	0.0471 (7)	0.0255 (6)	0.0279 (6)	0.0162 (5)	−0.0027 (5)	0.0050 (5)
C19	0.0373 (9)	0.0333 (9)	0.0275 (8)	0.0111 (7)	0.0001 (7)	0.0047 (7)

Geometric parameters (Å, º) top

C1—N1	1.3428 (19)	O1—C11	1.427 (2)
C1—N3	1.3453 (19)	C11—H11A	0.9700
C1—N2	1.3497 (19)	C11—H11B	0.9700
N1—C2	1.3395 (19)	C11—H11C	0.9700
C2—C3	1.392 (2)	C12—C13	1.379 (2)
C2—C5	1.492 (2)	C12—C17	1.400 (2)
C3—C4	1.388 (2)	C13—C14	1.394 (2)
C3—H3	0.9400	C13—H13	0.9400
C4—N2	1.3349 (19)	C14—O2	1.3702 (18)
C4—C12	1.489 (2)	C14—C15	1.382 (2)
N3—H3A	0.8700	C15—C16	1.391 (2)
N3—H3B	0.8700	C15—H15	0.9400
C5—C10	1.397 (2)	C16—O3	1.3704 (17)
C5—C6	1.406 (2)	C16—C17	1.382 (2)
C6—O1	1.3675 (19)	C17—H17	0.9400
C6—C7	1.390 (2)	O2—C18	1.4246 (18)
C7—C8	1.375 (2)	C18—H18A	0.9700
C7—H7	0.9400	C18—H18B	0.9700
C8—C9	1.374 (3)	C18—H18C	0.9700
C8—H8	0.9400	O3—C19	1.4199 (19)
C9—C10	1.378 (2)	C19—H19A	0.9700
C9—H9	0.9400	C19—H19B	0.9700
C10—H10	0.9400	C19—H19C	0.9700

N1—C1—N3	116.69 (13)	O1—C11—H11B	109.5
N1—C1—N2	126.16 (14)	H11A—C11—H11B	109.5
N3—C1—N2	117.15 (13)	O1—C11—H11C	109.5
C2—N1—C1	117.58 (13)	H11A—C11—H11C	109.5
N1—C2—C3	120.33 (13)	H11B—C11—H11C	109.5
N1—C2—C5	114.92 (13)	C13—C12—C17	120.67 (14)
C3—C2—C5	124.63 (14)	C13—C12—C4	120.77 (13)
C4—C3—C2	117.65 (14)	C17—C12—C4	118.48 (14)
C4—C3—H3	121.2	C12—C13—C14	119.40 (14)
C2—C3—H3	121.2	C12—C13—H13	120.3
N2—C4—C3	122.85 (14)	C14—C13—H13	120.3
N2—C4—C12	116.92 (13)	O2—C14—C15	123.43 (13)
C3—C4—C12	120.12 (13)	O2—C14—C13	115.83 (13)
C4—N2—C1	115.26 (13)	C15—C14—C13	120.73 (14)
C1—N3—H3A	120.0	C14—C15—C16	119.08 (14)
C1—N3—H3B	120.0	C14—C15—H15	120.5
H3A—N3—H3B	120.0	C16—C15—H15	120.5
C10—C5—C6	117.11 (14)	O3—C16—C17	124.54 (14)
C10—C5—C2	117.29 (14)	O3—C16—C15	114.35 (13)
C6—C5—C2	125.53 (14)	C17—C16—C15	121.11 (13)
O1—C6—C7	121.48 (14)	C16—C17—C12	118.91 (14)
O1—C6—C5	118.28 (13)	C16—C17—H17	120.5
C7—C6—C5	120.23 (15)	C12—C17—H17	120.5
C8—C7—C6	120.64 (16)	C14—O2—C18	116.94 (12)
C8—C7—H7	119.7	O2—C18—H18A	109.5
C6—C7—H7	119.7	O2—C18—H18B	109.5
C9—C8—C7	120.26 (16)	H18A—C18—H18B	109.5
C9—C8—H8	119.9	O2—C18—H18C	109.5
C7—C8—H8	119.9	H18A—C18—H18C	109.5
C8—C9—C10	119.40 (16)	H18B—C18—H18C	109.5
C8—C9—H9	120.3	C16—O3—C19	117.23 (12)
C10—C9—H9	120.3	O3—C19—H19A	109.5
C9—C10—C5	122.32 (16)	O3—C19—H19B	109.5
C9—C10—H10	118.8	H19A—C19—H19B	109.5
C5—C10—H10	118.8	O3—C19—H19C	109.5
C6—O1—C11	117.68 (13)	H19A—C19—H19C	109.5
O1—C11—H11A	109.5	H19B—C19—H19C	109.5

N3—C1—N1—C2	178.82 (14)	C6—C5—C10—C9	0.8 (2)
N2—C1—N1—C2	−1.4 (2)	C2—C5—C10—C9	−176.38 (15)
C1—N1—C2—C3	−2.6 (2)	C7—C6—O1—C11	3.7 (2)
C1—N1—C2—C5	173.46 (13)	C5—C6—O1—C11	−175.69 (15)
N1—C2—C3—C4	4.4 (2)	N2—C4—C12—C13	−140.95 (15)
C5—C2—C3—C4	−171.27 (14)	C3—C4—C12—C13	42.5 (2)
C2—C3—C4—N2	−2.4 (2)	N2—C4—C12—C17	42.3 (2)
C2—C3—C4—C12	173.89 (14)	C3—C4—C12—C17	−134.23 (16)
C3—C4—N2—C1	−1.2 (2)	C17—C12—C13—C14	0.9 (2)
C12—C4—N2—C1	−177.64 (13)	C4—C12—C13—C14	−175.80 (14)
N1—C1—N2—C4	3.3 (2)	C12—C13—C14—O2	−177.38 (13)
N3—C1—N2—C4	−176.92 (14)	C12—C13—C14—C15	2.2 (2)
N1—C2—C5—C10	−13.77 (19)	O2—C14—C15—C16	175.90 (14)
C3—C2—C5—C10	162.12 (14)	C13—C14—C15—C16	−3.6 (2)
N1—C2—C5—C6	169.36 (14)	C14—C15—C16—O3	−177.70 (14)
C3—C2—C5—C6	−14.8 (2)	C14—C15—C16—C17	2.1 (2)
C10—C5—C6—O1	177.62 (14)	O3—C16—C17—C12	−179.36 (14)
C2—C5—C6—O1	−5.5 (2)	C15—C16—C17—C12	0.9 (2)
C10—C5—C6—C7	−1.8 (2)	C13—C12—C17—C16	−2.4 (2)
C2—C5—C6—C7	175.08 (15)	C4—C12—C17—C16	174.36 (14)
O1—C6—C7—C8	−178.07 (16)	C15—C14—O2—C18	−4.5 (2)
C5—C6—C7—C8	1.3 (3)	C13—C14—O2—C18	175.04 (14)
C6—C7—C8—C9	0.3 (3)	C17—C16—O3—C19	−4.9 (2)
C7—C8—C9—C10	−1.3 (3)	C15—C16—O3—C19	174.89 (13)
C8—C9—C10—C5	0.8 (3)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N3—H3B···N2ⁱ	0.87	2.28	3.1374 (19)	167
N3—H3A···O3ⁱⁱ	0.87	2.39	3.2545 (17)	175

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

Funding information

The authors acknowledge financial support from the Basic Science Research Program (award No. NRF– 2016R1D1A1B03931623).

References

Bruker (2012). APEX2, SAINT and SADABS, Bruker AXS Inc. Madison, Wisconsin, USA. Google Scholar
Giridhar, R., Tamboli, R. S., Ramajayam, R., Prajapati, D. G. & Yadav, M. R. (2012). Eur. J. Med. Chem. 50, 428–432. Web of Science CrossRef Google Scholar
Koh, D., Jung, Y., Kim, B. S., Ahn, S. & Lim, Y. (2016). Magn. Reson. Chem. 54, 842–851. Web of Science CrossRef Google Scholar
Lee, Y., Kim, B. S., Ahn, S., Koh, D., Lee, Y. H., Shin, S. Y. & Lim, Y. (2016). Bioorg. Chem. 68, 166–176. Web of Science CrossRef Google Scholar
Lee, J., Kim, K.-H. & Jeong, S. (2011). Bioorg. Med. Chem. Lett. 21, 4203–4205. Web of Science CrossRef Google Scholar
Nagarajan, S., Shanmugavelan, P., Sathishkumar, M., Selvi, R., Ponnuswamy, A., Harikrishnan, H., Shanmugaiah, V. & Murugavel, S. (2014). Bioorg. Med. Chem. Lett. 24, 4999–5007. Web of Science CrossRef Google Scholar
Robinson, S. J., Petzer, J. P., Rousseau, A. L., Terre'Blanche, G., Petzer, A. & Lourens, A. C. U. (2016). Bioorg. Med. Chem. Lett. 26, 734–738. Web of Science CrossRef Google Scholar
Sangeetha, R., Edison, B., Thanikasalam, K., Kavitha, S. J. & Balasubramani, K. (2016). IUCrData, 1, x160794. Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Sheldrick, G. M. (2015). Acta Cryst. C71, 3–8. Web of Science CrossRef IUCr Journals Google Scholar
Singh, N., Pandey, S. K., Anand, N., Dwivedi, R., Singh, S., Sinha, S. K., Chaturvedi, V., Jaiswal, N., Srivastava, A. K., Shah, P., Siddiqui, M. I. & Tripathi, R. P. (2011). Bioorg. Med. Chem. Lett. 21, 4404–4408. Web of Science CrossRef Google Scholar
Thanigaimani, K., Khalib, N. C., Arshad, S. & Razak, I. A. (2012). Acta Cryst. E68, o3318. CrossRef IUCr Journals Google Scholar
Westrip, S. P. (2010). J. Appl. Cryst. 43, 920–925. Web of Science CrossRef CAS IUCr Journals Google Scholar

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