2-(2,5-Dimeth­oxy­phen­yl)-N-[2-(4-hy­droxy­phen­yl)eth­yl]acetamide

Choi, H.; Shim, Y.S.; Han, B.H.; Kang, S.K.; Sung, C.K.

doi:10.1107/S1600536812008975

organic compounds

CRYSTALLOGRAPHIC
COMMUNICATIONS

ISSN: 2056-9890

Volume 68| Part 4| April 2012| Page o966

doi:10.1107/S1600536812008975

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2-(2,5-Dimethoxyphenyl)-N-[2-(4-hydroxyphenyl)ethyl]acetamide

Hyeong Choi,^a Yong Suk Shim,^a Byung Hee Han,^a Sung Kwon Kang ^a ^* and Chang Keun Sung ^b

^aDepartment of Chemistry, Chungnam National University, Daejeon 305-764, Republic of Korea, and ^bDepartment of Food Science and Technology, Chungnam National University, Daejeon 305-764, Republic of Korea
^*Correspondence e-mail: skkang@cnu.ac.kr

(Received 28 February 2012; accepted 29 February 2012; online 7 March 2012)

In the title compound, C₁₈H₂₁NO₄, the dihedral angles between the acetamide group and the methoxy- and hydroxy-substitured benzene rings are 80.81 (5) and 8.19 (12)°, respectively. The benzene rings are twisted with respect to each other, making a dihedral angle of 72.89 (5)°. In the crystal, N—H⋯O and O—H⋯O hydrogen bonds link the molecules into a three-dimensional network.

Related literature

For general background to tyrosinase, see: Kubo et al. (2000 ). For the development of tyrosinase inhibitors, see: Lemic-Stojcevic et al. (1995 ); Battaini et al. (2000 ); Cabanes et al. (1994 ); Thanigaimalai et al. (2010 ).

Experimental

Crystal data

C₁₈H₂₁NO₄
M_r = 315.36
Orthorhombic, P 2₁ 2₁ 2₁
a = 8.1628 (8) Å
b = 12.0701 (11) Å
c = 17.0176 (16) Å
V = 1676.7 (3) Å³
Z = 4
Mo Kα radiation
μ = 0.09 mm⁻¹
T = 296 K
0.3 × 0.23 × 0.1 mm

Data collection

Bruker SMART CCD area-detector diffractometer
8417 measured reflections
3638 independent reflections
2352 reflections with I > 2σ(I)
R_int = 0.063

Refinement

R[F² > 2σ(F²)] = 0.040
wR(F²) = 0.088
S = 0.87
3638 reflections
216 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.11 e Å⁻³
Δρ_min = −0.12 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N10—H10⋯O19ⁱ	0.88 (2)	2.16 (2)	3.023 (2)	165.4 (19)
O19—H19⋯O9ⁱⁱ	0.87 (3)	1.76 (3)	2.6289 (19)	174 (3)
Symmetry codes: (i) $[x-{\script{1\over 2}}, -y+{\script{3\over 2}}, -z+1]$ ; (ii) $[-x+{\script{3\over 2}}, -y+1, z+{\script{1\over 2}}]$ .

Data collection: SMART (Bruker, 2002 ); cell refinement: SAINT (Bruker, 2002); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997 ); software used to prepare material for publication: WinGX (Farrugia, 1999 ).

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536812008975/tk5063sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536812008975/tk5063Isup2.hkl

Supporting information file. DOI: 10.1107/S1600536812008975/tk5063Isup3.cml

checkCIF report

Comment top

Tyrosinase is a copper containing enzyme which acts as a catalyst in two different reactions involving the hydroxylation of monophenols to o-diphenols and the oxidation of the o-diphenols to o-quinones. This class of enzyme is widely distributed in the plant, animal and microorganism kingdoms (Kubo et al., 2000), and its inhibition is one of the major strategies in developing new whitening agents. Over the last few decades, various tyrosinase inhibitors, including azelaic acid (Lemic-Stojcevic et al., 1995), kojic acid (Battaini et al., 2000), arbutin (Cabanes et al., 1994), and N-phenylthiourea (PTU) (Thanigaimalai et al., 2010) have been studied. But some of their individual activities are either not potent enough to be considered of practical use or not compatible with safety regulations for food and cosmetic additives. In our continuing search for tyrosinase inhibitors, we have synthesized the title compound, (I), from the reaction of 2,5-dimethoxyphenyl acetyl chloride and tyramine under ambient conditions. Herein, the crystal structure of (I) is described (Fig. 1).

The 2,4-dimethoxyphenyl and 3-hydroxyphenyl moieties are almost planar with r.m.s. deviations of 0.008 and 0.009 Å, respectively, from their corresponding least-squares planes. The dihedral angles between the acetamide group (C7–N10) and the benzene rings (C1–C6 + O20 and O22; and C12–O19) are 80.81 (5) and 8.19 (12)°, respectively. The benzene groups are twisted with respect to each other making a dihedral angle of 72.89 (5)°. The presence of intermolecular N10—H10···O19ⁱ and O19—H19···O9ⁱⁱ [symmetry codes: (i) x - 1/2, -y + 3/2, -z + 1, (ii) -x + 3/2, -y + 1, z + 1/2] hydrogen bonds link the molecules into a three-dimensional network (Fig. 2 and Table 1).

Related literature top

For general background to tyrosinase, see: Kubo et al. (2000). For the development of tyrosinase inhibitors, see: Lemic-Stojcevic et al. (1995); Battaini et al. (2000); Cabanes et al. (1994); Thanigaimalai et al. (2010).

Experimental top

The starting materials, 2,5-dimethoxyphenyl acetyl chloride and tyramine, were purchased from Sigma Chemical Co. Solvents for organic synthesis were redistilled before use. All other chemicals and solvents were of analytical grade and were used without further purification. The title compound was prepared from the reaction of 2,5-dimethoxyphenyl acetyl chloride (0.21 g, 1.0 mmol) and tyramine (0.14 g, 1.0 mmol) by simple substitution in THF (6 ml) triethylamine (0.12 g, 1.2 mmol). The solvent was removed under reduced pressure. The mixture was purified by column chromatography on silica gel (2:1 dichloromethane/ethylacetate) to give the title compound. Colourless crystals were obtained by slow evaporation of its ethanol solution at room temperature.

Structure description top

For general background to tyrosinase, see: Kubo et al. (2000). For the development of tyrosinase inhibitors, see: Lemic-Stojcevic et al. (1995); Battaini et al. (2000); Cabanes et al. (1994); Thanigaimalai et al. (2010).

Computing details top

Data collection: SMART (Bruker, 2002); cell refinement: SAINT (Bruker, 2002); data reduction: SAINT (Bruker, 2002); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures top

	Fig. 1. Molecular structure of the title compound, showing the atom-numbering scheme and 30% probability ellipsoids.
	Fig. 2. Part of the packing diagram of the title compound, showing a three-dimensional network of molecules linked by intermolecular N—H···O and O—H···O hydrogen bonds (dashed lines).

2-(2,5-Dimethoxyphenyl)-N-[2-(4-hydroxyphenyl)ethyl]acetamide top

Crystal data top

C₁₈H₂₁NO₄	F(000) = 672
M_r = 315.36	D_x = 1.249 Mg m⁻³
Orthorhombic, P2₁2₁2₁	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2ab	Cell parameters from 2320 reflections
a = 8.1628 (8) Å	θ = 2.9–23.6°
b = 12.0701 (11) Å	µ = 0.09 mm⁻¹
c = 17.0176 (16) Å	T = 296 K
V = 1676.7 (3) Å³	Block, colourless
Z = 4	0.3 × 0.23 × 0.1 mm

Data collection top

Bruker SMART CCD area-detector diffractometer	R_int = 0.063
Graphite monochromator	θ_max = 27.5°, θ_min = 2.8°
φ and ω scans	h = −4→10
8417 measured reflections	k = −15→7
3638 independent reflections	l = −18→21
2352 reflections with I > 2σ(I)

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)] = 0.040	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.088	H atoms treated by a mixture of independent and constrained refinement
S = 0.87	w = 1/[σ²(F_o²) + (0.0365P)²] where P = (F_o² + 2F_c²)/3
3638 reflections	(Δ/σ)_max < 0.001
216 parameters	Δρ_max = 0.11 e Å⁻³
0 restraints	Δρ_min = −0.12 e Å⁻³

Crystal data top

C₁₈H₂₁NO₄	V = 1676.7 (3) Å³
M_r = 315.36	Z = 4
Orthorhombic, P2₁2₁2₁	Mo Kα radiation
a = 8.1628 (8) Å	µ = 0.09 mm⁻¹
b = 12.0701 (11) Å	T = 296 K
c = 17.0176 (16) Å	0.3 × 0.23 × 0.1 mm

Data collection top

Bruker SMART CCD area-detector diffractometer	2352 reflections with I > 2σ(I)
8417 measured reflections	R_int = 0.063
3638 independent reflections

Refinement top

R[F² > 2σ(F²)] = 0.040	0 restraints
wR(F²) = 0.088	H atoms treated by a mixture of independent and constrained refinement
S = 0.87	Δρ_max = 0.11 e Å⁻³
3638 reflections	Δρ_min = −0.12 e Å⁻³
216 parameters

Special details top

Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'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 > 2σ(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
C1	0.4043 (2)	0.70567 (12)	0.09969 (11)	0.0437 (4)
C2	0.2961 (2)	0.62946 (13)	0.13350 (11)	0.0488 (5)
C3	0.2247 (2)	0.54873 (14)	0.08716 (13)	0.0563 (5)
H3	0.153	0.4979	0.1096	0.068*
C4	0.2590 (2)	0.54310 (14)	0.00842 (12)	0.0562 (5)
H4	0.2107	0.4882	−0.0221	0.067*
C5	0.3644 (2)	0.61811 (14)	−0.02606 (12)	0.0516 (5)
C6	0.4357 (2)	0.69979 (13)	0.02022 (11)	0.0472 (5)
H6	0.5056	0.7513	−0.0028	0.057*
C7	0.4814 (2)	0.79400 (13)	0.15008 (11)	0.0475 (5)
H7A	0.396	0.8424	0.1699	0.057*
H7B	0.5543	0.8383	0.1178	0.057*
C8	0.5769 (2)	0.74773 (14)	0.21872 (12)	0.0496 (5)
O9	0.67141 (17)	0.66858 (11)	0.21107 (9)	0.0710 (4)
N10	0.5600 (2)	0.80014 (13)	0.28703 (10)	0.0532 (4)
H10	0.485 (3)	0.8525 (17)	0.2849 (12)	0.073 (7)*
C11	0.6334 (3)	0.76130 (16)	0.35966 (12)	0.0607 (5)
H11A	0.6477	0.8236	0.395	0.073*
H11B	0.741	0.731	0.3484	0.073*
C12	0.5315 (3)	0.67421 (17)	0.39979 (13)	0.0715 (6)
H12A	0.421	0.7022	0.4064	0.086*
H12B	0.5258	0.6094	0.3662	0.086*
C13	0.5972 (2)	0.64031 (15)	0.47870 (12)	0.0544 (5)
C14	0.5678 (3)	0.70159 (14)	0.54505 (13)	0.0630 (6)
H14	0.5077	0.7668	0.5407	0.076*
C15	0.6242 (3)	0.66973 (15)	0.61796 (13)	0.0624 (6)
H15	0.601	0.7126	0.662	0.075*
C16	0.7159 (2)	0.57352 (14)	0.62542 (12)	0.0514 (5)
C17	0.7467 (3)	0.51175 (15)	0.56022 (12)	0.0623 (5)
H17	0.8067	0.4465	0.5645	0.075*
C18	0.6895 (3)	0.54522 (16)	0.48775 (13)	0.0671 (6)
H18	0.7137	0.5026	0.4437	0.081*
O19	0.7706 (2)	0.54495 (11)	0.69866 (9)	0.0700 (4)
H19	0.794 (4)	0.475 (2)	0.7052 (16)	0.139 (12)*
O20	0.26868 (18)	0.64349 (9)	0.21211 (8)	0.0633 (4)
C21	0.1722 (3)	0.56269 (18)	0.25170 (14)	0.0856 (8)
H21A	0.162	0.5826	0.3061	0.128*
H21B	0.2242	0.4916	0.2475	0.128*
H21C	0.0655	0.5594	0.2282	0.128*
O22	0.38811 (19)	0.60474 (12)	−0.10495 (9)	0.0749 (5)
C23	0.4980 (3)	0.6780 (2)	−0.14310 (14)	0.0836 (7)
H23A	0.5043	0.6595	−0.1979	0.125*
H23B	0.6047	0.6714	−0.1198	0.125*
H23C	0.4595	0.7527	−0.1375	0.125*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
C1	0.0431 (10)	0.0391 (8)	0.0488 (13)	0.0005 (8)	−0.0018 (9)	0.0023 (8)
C2	0.0517 (11)	0.0435 (9)	0.0512 (13)	−0.0025 (8)	0.0037 (10)	0.0049 (9)
C3	0.0487 (11)	0.0460 (9)	0.0743 (15)	−0.0108 (9)	0.0024 (11)	0.0050 (10)
C4	0.0532 (12)	0.0503 (10)	0.0651 (15)	−0.0140 (10)	−0.0054 (11)	−0.0081 (9)
C5	0.0463 (10)	0.0565 (10)	0.0521 (14)	−0.0034 (9)	−0.0060 (10)	−0.0046 (9)
C6	0.0427 (10)	0.0465 (9)	0.0523 (13)	−0.0066 (8)	−0.0032 (9)	0.0015 (8)
C7	0.0550 (12)	0.0409 (8)	0.0465 (12)	−0.0047 (8)	0.0034 (9)	0.0004 (8)
C8	0.0484 (11)	0.0423 (8)	0.0582 (14)	−0.0069 (9)	0.0022 (10)	−0.0024 (9)
O9	0.0680 (9)	0.0593 (8)	0.0858 (11)	0.0182 (7)	−0.0068 (8)	−0.0132 (8)
N10	0.0631 (11)	0.0482 (8)	0.0483 (11)	0.0020 (9)	−0.0041 (9)	0.0003 (8)
C11	0.0649 (13)	0.0622 (11)	0.0552 (13)	−0.0086 (10)	−0.0084 (11)	0.0006 (10)
C12	0.0661 (13)	0.0735 (13)	0.0750 (16)	−0.0123 (12)	−0.0153 (12)	0.0217 (11)
C13	0.0456 (11)	0.0557 (10)	0.0618 (14)	−0.0060 (9)	−0.0070 (10)	0.0102 (10)
C14	0.0607 (13)	0.0487 (10)	0.0795 (17)	0.0101 (10)	0.0030 (12)	0.0125 (11)
C15	0.0743 (14)	0.0474 (10)	0.0656 (15)	0.0058 (10)	0.0069 (12)	−0.0013 (10)
C16	0.0557 (12)	0.0453 (9)	0.0532 (13)	−0.0073 (9)	−0.0089 (10)	0.0053 (9)
C17	0.0690 (13)	0.0551 (10)	0.0628 (14)	0.0164 (10)	−0.0085 (13)	−0.0018 (11)
C18	0.0808 (16)	0.0606 (11)	0.0600 (15)	0.0111 (12)	−0.0088 (12)	−0.0068 (11)
O19	0.0949 (11)	0.0539 (8)	0.0611 (10)	−0.0033 (8)	−0.0192 (9)	0.0029 (7)
O20	0.0770 (9)	0.0559 (7)	0.0569 (9)	−0.0153 (7)	0.0127 (8)	0.0061 (7)
C21	0.113 (2)	0.0654 (13)	0.0782 (17)	−0.0159 (14)	0.0298 (15)	0.0162 (12)
O22	0.0808 (11)	0.0891 (10)	0.0548 (10)	−0.0292 (9)	0.0034 (8)	−0.0165 (8)
C23	0.0788 (17)	0.1105 (18)	0.0614 (16)	−0.0286 (15)	0.0078 (13)	−0.0088 (13)

Geometric parameters (Å, º) top

C1—C6	1.378 (2)	C12—H12A	0.97
C1—C2	1.399 (2)	C12—H12B	0.97
C1—C7	1.506 (2)	C13—C14	1.371 (3)
C2—O20	1.367 (2)	C13—C18	1.382 (3)
C2—C3	1.382 (3)	C14—C15	1.378 (3)
C3—C4	1.371 (3)	C14—H14	0.93
C3—H3	0.93	C15—C16	1.387 (3)
C4—C5	1.380 (3)	C15—H15	0.93
C4—H4	0.93	C16—C17	1.360 (3)
C5—O22	1.366 (2)	C16—O19	1.368 (2)
C5—C6	1.390 (2)	C17—C18	1.379 (3)
C6—H6	0.93	C17—H17	0.93
C7—C8	1.511 (3)	C18—H18	0.93
C7—H7A	0.97	O19—H19	0.87 (3)
C7—H7B	0.97	O20—C21	1.423 (2)
C8—O9	1.235 (2)	C21—H21A	0.96
C8—N10	1.331 (2)	C21—H21B	0.96
N10—C11	1.452 (2)	C21—H21C	0.96
N10—H10	0.88 (2)	O22—C23	1.417 (2)
C11—C12	1.504 (3)	C23—H23A	0.96
C11—H11A	0.97	C23—H23B	0.96
C11—H11B	0.97	C23—H23C	0.96
C12—C13	1.503 (3)

C6—C1—C2	119.14 (16)	C11—C12—H12A	108.9
C6—C1—C7	121.17 (15)	C13—C12—H12B	108.9
C2—C1—C7	119.67 (17)	C11—C12—H12B	108.9
O20—C2—C3	125.22 (16)	H12A—C12—H12B	107.7
O20—C2—C1	115.11 (15)	C14—C13—C18	116.86 (18)
C3—C2—C1	119.67 (18)	C14—C13—C12	121.78 (18)
C4—C3—C2	120.45 (17)	C18—C13—C12	121.36 (19)
C4—C3—H3	119.8	C13—C14—C15	122.16 (17)
C2—C3—H3	119.8	C13—C14—H14	118.9
C3—C4—C5	120.68 (17)	C15—C14—H14	118.9
C3—C4—H4	119.7	C14—C15—C16	119.76 (19)
C5—C4—H4	119.7	C14—C15—H15	120.1
O22—C5—C4	115.38 (16)	C16—C15—H15	120.1
O22—C5—C6	125.57 (17)	C17—C16—O19	123.00 (17)
C4—C5—C6	119.05 (18)	C17—C16—C15	118.94 (18)
C1—C6—C5	120.99 (17)	O19—C16—C15	118.06 (19)
C1—C6—H6	119.5	C16—C17—C18	120.41 (18)
C5—C6—H6	119.5	C16—C17—H17	119.8
C1—C7—C8	113.21 (13)	C18—C17—H17	119.8
C1—C7—H7A	108.9	C17—C18—C13	121.8 (2)
C8—C7—H7A	108.9	C17—C18—H18	119.1
C1—C7—H7B	108.9	C13—C18—H18	119.1
C8—C7—H7B	108.9	C16—O19—H19	115.6 (19)
H7A—C7—H7B	107.7	C2—O20—C21	117.97 (15)
O9—C8—N10	121.66 (18)	O20—C21—H21A	109.5
O9—C8—C7	121.78 (18)	O20—C21—H21B	109.5
N10—C8—C7	116.48 (16)	H21A—C21—H21B	109.5
C8—N10—C11	123.19 (17)	O20—C21—H21C	109.5
C8—N10—H10	112.2 (14)	H21A—C21—H21C	109.5
C11—N10—H10	123.7 (14)	H21B—C21—H21C	109.5
N10—C11—C12	112.56 (16)	C5—O22—C23	117.79 (15)
N10—C11—H11A	109.1	O22—C23—H23A	109.5
C12—C11—H11A	109.1	O22—C23—H23B	109.5
N10—C11—H11B	109.1	H23A—C23—H23B	109.5
C12—C11—H11B	109.1	O22—C23—H23C	109.5
H11A—C11—H11B	107.8	H23A—C23—H23C	109.5
C13—C12—C11	113.50 (18)	H23B—C23—H23C	109.5
C13—C12—H12A	108.9

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N10—H10···O19ⁱ	0.88 (2)	2.16 (2)	3.023 (2)	165.4 (19)
O19—H19···O9ⁱⁱ	0.87 (3)	1.76 (3)	2.6289 (19)	174 (3)

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

Experimental details

Crystal data
Chemical formula	C₁₈H₂₁NO₄
M_r	315.36
Crystal system, space group	Orthorhombic, P2₁2₁2₁
Temperature (K)	296
a, b, c (Å)	8.1628 (8), 12.0701 (11), 17.0176 (16)
V (Å³)	1676.7 (3)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.09
Crystal size (mm)	0.3 × 0.23 × 0.1

Data collection
Diffractometer	Bruker SMART CCD area-detector
Absorption correction	–
No. of measured, independent and observed [I > 2σ(I)] reflections	8417, 3638, 2352
R_int	0.063
(sin θ/λ)_max (Å⁻¹)	0.650

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.040, 0.088, 0.87
No. of reflections	3638
No. of parameters	216
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.11, −0.12

Computer programs: SMART (Bruker, 2002), SAINT (Bruker, 2002), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), ORTEP-3 for Windows (Farrugia, 1997), WinGX (Farrugia, 1999).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N10—H10···O19ⁱ	0.88 (2)	2.16 (2)	3.023 (2)	165.4 (19)
O19—H19···O9ⁱⁱ	0.87 (3)	1.76 (3)	2.6289 (19)	174 (3)

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

Acknowledgements

We wish to thank the DBIO company for partial support of this work.

References

Battaini, G., Monzani, E., Casella, L., Santagostini, L. & Pagliarin, R. (2000). J. Biol. Inorg. Chem. 5, 262–268. Web of Science CrossRef PubMed CAS Google Scholar
Bruker (2002). SAINT and SMART. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Cabanes, J., Chazarra, S. & Garcia-Carmona, F. (1994). J. Pharm. Pharmacol. 46, 982–985. CrossRef CAS PubMed Google Scholar
Farrugia, L. J. (1997). J. Appl. Cryst. 30, 565. CrossRef IUCr Journals Google Scholar
Farrugia, L. J. (1999). J. Appl. Cryst. 32, 837–838. CrossRef CAS IUCr Journals Google Scholar
Kubo, I., Kinst-Hori, I., Chaudhuri, S. K., Kubo, Y., Scanchez, Y. & Ogura, T. (2000). Bioorg. Med. Chem. 8, 1749–1755. Web of Science CrossRef PubMed CAS Google Scholar
Lemic-Stojcevic, L., Nias, A. H. & Breathnach, A. S. (1995). Exp. Dermatol. 4, 79–81. CrossRef CAS PubMed Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Thanigaimalai, P., Le, H. T. A., Lee, K. C., Bang, S. C., Sharma, V. K., Yun, C. Y., Roh, E., Hwang, B. Y., Kim, Y. S. & Jung, S. H. (2010). Bioorg. Med. Chem. Lett. 20, 2991–2993. Web of Science CrossRef CAS PubMed Google Scholar