organic compounds
N-(2,5-Dimethoxyphenyl)-N′-(4-hydroxyphenethyl)urea
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
In the title compound, C17H20N2O4, the 2,5-dimethoxyphenyl unit is almost planar, with an r.m.s. deviation of 0.015 Å. The dihedral angle between the 2,5-dimethoxyphenyl ring and the urea plane is 20.95 (8)°. The H atoms of the urea NH groups are positioned syn to each other. The molecular structure is stabilized by a short intramolecular N—H⋯O hydrogen bond. In the crystal, intermolecular 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); Perez-Gilbert & Garcia-Carmona (2001). For the development of tyrosinase inhibitors, see: Shiino et al. (2001); Khan et al. (2006); Garcia & Fulrton (1996); Kojima et al. (1995); Cabanes et al. (1994); Lemic-Stojcevic et al. 1995); Casanola-Martin et al. (2006); Thanigaimalai et al. (2010); Passi & Nazzaro-Porro (1981).
Experimental
Crystal data
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Data collection
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Refinement
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Data collection: SMART (Bruker, 2002); cell 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: DIAMOND (Brandenburg, 2010); software used to prepare material for publication: WinGX (Farrugia, 1999).
Supporting information
https://doi.org/10.1107/S1600536810038535/jh2214sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536810038535/jh2214Isup2.hkl
The tyramine and 2,5-dimethoxyphenyl isocyanate were purchased from Sigma Chemical Co. Solvents used for organic synthesis were redistilled before use. All other chemicals and solvents were of analytical grade and used without further purification. The title compound (I) was prepared from the reaction of 2-(4-hydroxyphenyl)ethyl amine (0.20 g, 1 mmol) with 2,5-dimethoxyphenyl isocyanate (0.18 g, 1.2 mmol) in acetonitrile (8 ml) and added 4-(dimethylamino)pyridine (0.06 g, 0.5 mmol) as a catalyst, with stirring. The reaction was completed within 5 h at room temperature. The solvents were removed under reduced pressure. The solids collected and washed with dichloromethane. Removal of the solvent gave a light yellow solid (69%, m.p. 436 K). Single crystals were obtained by slow evaporation of the ethanol at room temperature.
The H atoms of the NH and OH groups were located in a difference Fourier map and refined freely. The remaining H atoms were positioned geometrically and refined using a riding model with C—H = 0.93–0.97 Å, and with Uiso(H) = 1.2Ueq (C) for aromatic and metylene, and 1.5Ueq(C) for methyl H atoms.
Tyrosinase known as a polyphenol oxidase, is a multifunctional copper-containing enzyme widely distributed in nature. It is the key enzyme in the undesirable browning of fruits and vegetables, and coloring of skin, hair, and eyes in animals (Kubo et al., 2000; Perez-Gilbert & Garcia-Carmona, 2001). Nowadays, tyrosinase inhibitors are thought to be clinically useful for the treatment of some dermatological disorders associated with melanin hyperpigmentation (Shiino et al., 2001) and useful in cosmetic products and food industry (Khan et al., 2006). Recently, various tyrosinase inhibitors have been reported such as hydroquinone (Garcia & Fulrton, 1996), ascorbic acid derivatives (Kojima et al., 1995), kojic acid (Cabanes et al., 1994), azelaic acid (Lemic-Stojcevic et al., 1995), arbutin (Casanola-Martin et al., 2006) and N-phenylthiourea (PTU) (Thanigaimalai et al., 2010). Most of the tyrosinase inhibitors are phenol/catechol derivatives, structurally similar to tyrosine or L-DOPA, which act as suicide substrates of tyrosinase (Passi & Nazzaro-Porro, 1981). However, most of them are not potent enough to put into practical use due to their weak individual activities or safety concerns. Undoubtedly, it is required to search and develop novel tyrosinase inhibitors with better activities together with lower side effects. In continuing our research on the development of tyrosinase inhibitors for new whitening agents, we have synthesized the title compound, (I), from the reaction of 2-(4-hydroxyphenyl)ethyl amine and 2,5-dimethoxyphenyl isocyanate under ambient condition. Here, we report the
of the title compound, (I).The 2,5-dimethoxyphenyl moiety is almost planar with r.m.s. deviation of 0.015 Å from the corresponding least-squares plane defined by the nine constituent atoms. The dihedral angle between the phenyl ring and the plane of urea moiety is 20.95 (8) °. The molecular structure is stabilized by a short intramolecular N7—H7···O20 hydrogen bond (Fig. 1). In the crystal, intermolecular N—H···O and O—H···O hydrogen bonds link the molecules into a three-dimensional network (Fig. 2, Table 1). The H atoms of the NH groups of urea are positioned syn to each other.
For general background to tyrosinase, see: Kubo et al. (2000); Perez-Gilbert & Garcia-Carmona (2001). For the development of tyrosinase inhibitors, see: Shiino et al. (2001); Khan et al. (2006); Garcia & Fulrton (1996); Kojima et al. (1995); Cabanes et al. (1994); Lemic-Stojcevic et al. 1995); Casanola-Martin et al. (2006); Thanigaimalai et al. (2010); Passi & Nazzaro-Porro (1981).
Data collection: SMART (Bruker, 2002); cell
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: DIAMOND (Brandenburg, 2010); software used to prepare material for publication: WinGX (Farrugia, 1999).C17H20N2O4 | F(000) = 672 |
Mr = 316.35 | Dx = 1.265 Mg m−3 |
Monoclinic, P21/n | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2yn | Cell parameters from 5519 reflections |
a = 10.7275 (6) Å | θ = 2.5–27.8° |
b = 9.6016 (5) Å | µ = 0.09 mm−1 |
c = 16.9388 (10) Å | T = 296 K |
β = 107.838 (2)° | Needle, colourless |
V = 1660.84 (16) Å3 | 0.31 × 0.27 × 0.13 mm |
Z = 4 |
Bruker SMART CCD area-detector diffractometer | Rint = 0.044 |
φ and ω scans | θmax = 26.0°, θmin = 2.0° |
13358 measured reflections | h = −13→6 |
3184 independent reflections | k = −11→9 |
2296 reflections with I > 2σ(I) | l = −20→16 |
Refinement on F2 | 0 restraints |
Least-squares matrix: full | H atoms treated by a mixture of independent and constrained refinement |
R[F2 > 2σ(F2)] = 0.059 | w = 1/[σ2(Fo2) + (0.0966P)2 + 0.4089P] where P = (Fo2 + 2Fc2)/3 |
wR(F2) = 0.186 | (Δ/σ)max < 0.001 |
S = 1.06 | Δρmax = 0.32 e Å−3 |
3184 reflections | Δρmin = −0.46 e Å−3 |
218 parameters |
C17H20N2O4 | V = 1660.84 (16) Å3 |
Mr = 316.35 | Z = 4 |
Monoclinic, P21/n | Mo Kα radiation |
a = 10.7275 (6) Å | µ = 0.09 mm−1 |
b = 9.6016 (5) Å | T = 296 K |
c = 16.9388 (10) Å | 0.31 × 0.27 × 0.13 mm |
β = 107.838 (2)° |
Bruker SMART CCD area-detector diffractometer | 2296 reflections with I > 2σ(I) |
13358 measured reflections | Rint = 0.044 |
3184 independent reflections |
R[F2 > 2σ(F2)] = 0.059 | 0 restraints |
wR(F2) = 0.186 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.06 | Δρmax = 0.32 e Å−3 |
3184 reflections | Δρmin = −0.46 e Å−3 |
218 parameters |
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. |
x | y | z | Uiso*/Ueq | ||
C1 | 0.3898 (2) | 0.5854 (2) | 0.12845 (14) | 0.0581 (5) | |
C2 | 0.5212 (2) | 0.6136 (3) | 0.13837 (16) | 0.0698 (7) | |
C3 | 0.5565 (3) | 0.6644 (3) | 0.0720 (2) | 0.0856 (8) | |
H3 | 0.644 | 0.6835 | 0.0783 | 0.103* | |
C4 | 0.4643 (3) | 0.6869 (3) | −0.00277 (19) | 0.0845 (8) | |
H4 | 0.4896 | 0.7201 | −0.0471 | 0.101* | |
C5 | 0.3347 (3) | 0.6610 (3) | −0.01298 (15) | 0.0724 (7) | |
C6 | 0.2967 (2) | 0.6085 (2) | 0.05238 (14) | 0.0636 (6) | |
H6 | 0.209 | 0.589 | 0.0452 | 0.076* | |
N7 | 0.35963 (18) | 0.5297 (2) | 0.19699 (12) | 0.0639 (5) | |
H7 | 0.423 (3) | 0.498 (3) | 0.2325 (16) | 0.068 (7)* | |
C8 | 0.24229 (19) | 0.5317 (2) | 0.21258 (12) | 0.0540 (5) | |
O9 | 0.14248 (14) | 0.58188 (19) | 0.16417 (9) | 0.0701 (5) | |
N10 | 0.24242 (19) | 0.4718 (2) | 0.28412 (11) | 0.0638 (5) | |
H10 | 0.315 (3) | 0.441 (3) | 0.3168 (16) | 0.075 (8)* | |
C11 | 0.1271 (2) | 0.4629 (3) | 0.31035 (13) | 0.0683 (7) | |
H11A | 0.1342 | 0.3814 | 0.3453 | 0.082* | |
H11B | 0.0514 | 0.4501 | 0.2618 | 0.082* | |
C12 | 0.1046 (2) | 0.5896 (3) | 0.35756 (13) | 0.0684 (7) | |
H12A | 0.0949 | 0.6706 | 0.322 | 0.082* | |
H12B | 0.0231 | 0.5774 | 0.3703 | 0.082* | |
C13 | 0.21277 (19) | 0.6172 (2) | 0.43716 (13) | 0.0558 (5) | |
C14 | 0.2326 (3) | 0.5296 (3) | 0.50382 (15) | 0.0820 (8) | |
H14 | 0.1792 | 0.4519 | 0.4992 | 0.098* | |
C15 | 0.3299 (3) | 0.5540 (3) | 0.57772 (16) | 0.0874 (9) | |
H15 | 0.3413 | 0.4926 | 0.6219 | 0.105* | |
C16 | 0.40944 (19) | 0.6679 (2) | 0.58626 (13) | 0.0597 (6) | |
C17 | 0.3892 (2) | 0.7585 (2) | 0.52187 (14) | 0.0638 (6) | |
H17 | 0.4404 | 0.8383 | 0.5274 | 0.077* | |
C18 | 0.2917 (2) | 0.7315 (2) | 0.44770 (14) | 0.0654 (6) | |
H18 | 0.2798 | 0.7935 | 0.4038 | 0.078* | |
O19 | 0.50449 (17) | 0.6876 (2) | 0.66089 (11) | 0.0816 (6) | |
H19 | 0.552 (3) | 0.759 (4) | 0.658 (2) | 0.122* | |
O20 | 0.60539 (16) | 0.5880 (3) | 0.21599 (12) | 0.0954 (7) | |
C21 | 0.7414 (3) | 0.6140 (7) | 0.2294 (2) | 0.1518 (19) | |
H21A | 0.7898 | 0.5914 | 0.2857 | 0.228* | |
H21B | 0.7541 | 0.7105 | 0.2192 | 0.228* | |
H21C | 0.7719 | 0.5574 | 0.1923 | 0.228* | |
O22 | 0.2495 (2) | 0.6902 (3) | −0.08960 (12) | 0.0991 (7) | |
C23 | 0.1155 (4) | 0.6852 (3) | −0.10046 (19) | 0.1056 (11) | |
H23A | 0.0681 | 0.7078 | −0.1569 | 0.158* | |
H23B | 0.094 | 0.7512 | −0.064 | 0.158* | |
H23C | 0.0919 | 0.5933 | −0.0879 | 0.158* |
U11 | U22 | U33 | U12 | U13 | U23 | |
C1 | 0.0566 (11) | 0.0614 (13) | 0.0551 (12) | 0.0002 (9) | 0.0154 (10) | −0.0068 (10) |
C2 | 0.0567 (13) | 0.0777 (16) | 0.0735 (15) | −0.0004 (11) | 0.0175 (12) | −0.0106 (12) |
C3 | 0.0665 (15) | 0.097 (2) | 0.100 (2) | −0.0084 (14) | 0.0355 (15) | −0.0010 (17) |
C4 | 0.0879 (18) | 0.0901 (19) | 0.0855 (19) | −0.0109 (15) | 0.0411 (16) | 0.0065 (15) |
C5 | 0.0828 (16) | 0.0724 (16) | 0.0603 (14) | −0.0089 (12) | 0.0195 (12) | 0.0028 (11) |
C6 | 0.0610 (12) | 0.0702 (15) | 0.0565 (13) | −0.0088 (10) | 0.0135 (10) | −0.0019 (11) |
N7 | 0.0488 (10) | 0.0852 (14) | 0.0512 (11) | 0.0095 (9) | 0.0059 (8) | 0.0050 (9) |
C8 | 0.0531 (11) | 0.0588 (12) | 0.0426 (10) | 0.0045 (9) | 0.0037 (9) | −0.0033 (9) |
O9 | 0.0538 (8) | 0.0941 (12) | 0.0551 (9) | 0.0151 (8) | 0.0057 (7) | 0.0144 (8) |
N10 | 0.0603 (11) | 0.0815 (13) | 0.0453 (10) | 0.0137 (9) | 0.0100 (8) | 0.0071 (9) |
C11 | 0.0644 (13) | 0.0858 (17) | 0.0483 (12) | −0.0152 (11) | 0.0079 (10) | −0.0045 (11) |
C12 | 0.0465 (11) | 0.1008 (18) | 0.0511 (12) | 0.0057 (11) | 0.0050 (9) | −0.0050 (12) |
C13 | 0.0456 (10) | 0.0698 (14) | 0.0466 (11) | 0.0055 (9) | 0.0061 (8) | −0.0026 (10) |
C14 | 0.0843 (17) | 0.0838 (17) | 0.0614 (14) | −0.0297 (14) | −0.0020 (12) | 0.0050 (13) |
C15 | 0.1003 (19) | 0.0795 (17) | 0.0587 (14) | −0.0219 (15) | −0.0109 (13) | 0.0176 (13) |
C16 | 0.0501 (11) | 0.0611 (13) | 0.0541 (12) | 0.0033 (9) | −0.0044 (9) | 0.0008 (10) |
C17 | 0.0597 (12) | 0.0574 (12) | 0.0646 (13) | −0.0045 (10) | 0.0047 (10) | 0.0023 (10) |
C18 | 0.0679 (14) | 0.0651 (14) | 0.0544 (12) | 0.0060 (11) | 0.0056 (10) | 0.0120 (10) |
O19 | 0.0738 (11) | 0.0760 (12) | 0.0659 (10) | −0.0059 (8) | −0.0214 (8) | 0.0041 (8) |
O20 | 0.0496 (9) | 0.1491 (19) | 0.0801 (12) | 0.0044 (10) | 0.0088 (8) | −0.0044 (12) |
C21 | 0.0506 (16) | 0.283 (6) | 0.114 (3) | −0.004 (2) | 0.0139 (17) | −0.020 (3) |
O22 | 0.0948 (14) | 0.1328 (18) | 0.0650 (11) | −0.0083 (12) | 0.0173 (10) | 0.0177 (11) |
C23 | 0.136 (3) | 0.073 | 0.0813 (19) | −0.0271 (17) | −0.0063 (19) | 0.0146 (15) |
C1—C6 | 1.385 (3) | C12—H12A | 0.97 |
C1—C2 | 1.394 (3) | C12—H12B | 0.97 |
C1—N7 | 1.403 (3) | C13—C18 | 1.364 (3) |
C2—O20 | 1.370 (3) | C13—C14 | 1.371 (3) |
C2—C3 | 1.381 (4) | C14—C15 | 1.382 (3) |
C3—C4 | 1.364 (4) | C14—H14 | 0.93 |
C3—H3 | 0.93 | C15—C16 | 1.367 (3) |
C4—C5 | 1.370 (4) | C15—H15 | 0.93 |
C4—H4 | 0.93 | C16—C17 | 1.360 (3) |
C5—O22 | 1.368 (3) | C16—O19 | 1.373 (2) |
C5—C6 | 1.387 (3) | C17—C18 | 1.391 (3) |
C6—H6 | 0.93 | C17—H17 | 0.93 |
N7—C8 | 1.363 (3) | C18—H18 | 0.93 |
N7—H7 | 0.82 (3) | O19—H19 | 0.86 (4) |
C8—O9 | 1.230 (2) | O20—C21 | 1.429 (3) |
C8—N10 | 1.341 (3) | C21—H21A | 0.96 |
N10—C11 | 1.440 (3) | C21—H21B | 0.96 |
N10—H10 | 0.86 (3) | C21—H21C | 0.96 |
C11—C12 | 1.515 (4) | O22—C23 | 1.394 (4) |
C11—H11A | 0.97 | C23—H23A | 0.96 |
C11—H11B | 0.97 | C23—H23B | 0.96 |
C12—C13 | 1.509 (3) | C23—H23C | 0.96 |
C6—C1—C2 | 119.7 (2) | C13—C12—H12B | 108.7 |
C6—C1—N7 | 123.2 (2) | C11—C12—H12B | 108.7 |
C2—C1—N7 | 117.1 (2) | H12A—C12—H12B | 107.6 |
O20—C2—C3 | 125.5 (2) | C18—C13—C14 | 116.88 (19) |
O20—C2—C1 | 115.2 (2) | C18—C13—C12 | 122.3 (2) |
C3—C2—C1 | 119.3 (2) | C14—C13—C12 | 120.8 (2) |
C4—C3—C2 | 120.7 (2) | C13—C14—C15 | 121.7 (2) |
C4—C3—H3 | 119.7 | C13—C14—H14 | 119.1 |
C2—C3—H3 | 119.7 | C15—C14—H14 | 119.1 |
C3—C4—C5 | 120.5 (3) | C16—C15—C14 | 120.3 (2) |
C3—C4—H4 | 119.7 | C16—C15—H15 | 119.8 |
C5—C4—H4 | 119.7 | C14—C15—H15 | 119.8 |
O22—C5—C4 | 116.1 (2) | C17—C16—C15 | 119.08 (19) |
O22—C5—C6 | 123.9 (2) | C17—C16—O19 | 122.8 (2) |
C4—C5—C6 | 120.0 (2) | C15—C16—O19 | 118.1 (2) |
C1—C6—C5 | 119.8 (2) | C16—C17—C18 | 119.7 (2) |
C1—C6—H6 | 120.1 | C16—C17—H17 | 120.1 |
C5—C6—H6 | 120.1 | C18—C17—H17 | 120.1 |
C8—N7—C1 | 127.99 (19) | C13—C18—C17 | 122.2 (2) |
C8—N7—H7 | 118.4 (18) | C13—C18—H18 | 118.9 |
C1—N7—H7 | 113.4 (18) | C17—C18—H18 | 118.9 |
O9—C8—N10 | 122.0 (2) | C16—O19—H19 | 110 (2) |
O9—C8—N7 | 122.9 (2) | C2—O20—C21 | 117.5 (3) |
N10—C8—N7 | 115.05 (18) | O20—C21—H21A | 109.5 |
C8—N10—C11 | 122.76 (19) | O20—C21—H21B | 109.5 |
C8—N10—H10 | 118.8 (17) | H21A—C21—H21B | 109.5 |
C11—N10—H10 | 118.4 (17) | O20—C21—H21C | 109.5 |
N10—C11—C12 | 114.0 (2) | H21A—C21—H21C | 109.5 |
N10—C11—H11A | 108.8 | H21B—C21—H21C | 109.5 |
C12—C11—H11A | 108.8 | C5—O22—C23 | 118.7 (2) |
N10—C11—H11B | 108.8 | O22—C23—H23A | 109.5 |
C12—C11—H11B | 108.8 | O22—C23—H23B | 109.5 |
H11A—C11—H11B | 107.7 | H23A—C23—H23B | 109.5 |
C13—C12—C11 | 114.19 (19) | O22—C23—H23C | 109.5 |
C13—C12—H12A | 108.7 | H23A—C23—H23C | 109.5 |
C11—C12—H12A | 108.7 | H23B—C23—H23C | 109.5 |
D—H···A | D—H | H···A | D···A | D—H···A |
N7—H7···O20 | 0.82 (3) | 2.23 (2) | 2.617 (3) | 109 (2) |
N7—H7···O19i | 0.82 (3) | 2.48 (3) | 3.182 (3) | 144 (2) |
N10—H10···O19i | 0.86 (3) | 2.23 (3) | 3.005 (3) | 150 (2) |
O19—H19···O9ii | 0.86 (4) | 1.80 (4) | 2.654 (3) | 172 (4) |
Symmetry codes: (i) −x+1, −y+1, −z+1; (ii) x+1/2, −y+3/2, z+1/2. |
Experimental details
Crystal data | |
Chemical formula | C17H20N2O4 |
Mr | 316.35 |
Crystal system, space group | Monoclinic, P21/n |
Temperature (K) | 296 |
a, b, c (Å) | 10.7275 (6), 9.6016 (5), 16.9388 (10) |
β (°) | 107.838 (2) |
V (Å3) | 1660.84 (16) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.09 |
Crystal size (mm) | 0.31 × 0.27 × 0.13 |
Data collection | |
Diffractometer | Bruker SMART CCD area-detector |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 13358, 3184, 2296 |
Rint | 0.044 |
(sin θ/λ)max (Å−1) | 0.617 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.059, 0.186, 1.06 |
No. of reflections | 3184 |
No. of parameters | 218 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.32, −0.46 |
Computer programs: SMART (Bruker, 2002), SAINT (Bruker, 2002), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), DIAMOND (Brandenburg, 2010), WinGX (Farrugia, 1999).
D—H···A | D—H | H···A | D···A | D—H···A |
N7—H7···O20 | 0.82 (3) | 2.23 (2) | 2.617 (3) | 109 (2) |
N7—H7···O19i | 0.82 (3) | 2.48 (3) | 3.182 (3) | 144 (2) |
N10—H10···O19i | 0.86 (3) | 2.23 (3) | 3.005 (3) | 150 (2) |
O19—H19···O9ii | 0.86 (4) | 1.80 (4) | 2.654 (3) | 172 (4) |
Symmetry codes: (i) −x+1, −y+1, −z+1; (ii) x+1/2, −y+3/2, z+1/2. |
Acknowledgements
This work is the result of a study performed under the `Human Resource Development Center for Economic Region Leading Industry' Project, supported by the Ministry of Education, Science & Technology (MEST) and the National Research Foundation of Korea (NRF).
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This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.
Tyrosinase known as a polyphenol oxidase, is a multifunctional copper-containing enzyme widely distributed in nature. It is the key enzyme in the undesirable browning of fruits and vegetables, and coloring of skin, hair, and eyes in animals (Kubo et al., 2000; Perez-Gilbert & Garcia-Carmona, 2001). Nowadays, tyrosinase inhibitors are thought to be clinically useful for the treatment of some dermatological disorders associated with melanin hyperpigmentation (Shiino et al., 2001) and useful in cosmetic products and food industry (Khan et al., 2006). Recently, various tyrosinase inhibitors have been reported such as hydroquinone (Garcia & Fulrton, 1996), ascorbic acid derivatives (Kojima et al., 1995), kojic acid (Cabanes et al., 1994), azelaic acid (Lemic-Stojcevic et al., 1995), arbutin (Casanola-Martin et al., 2006) and N-phenylthiourea (PTU) (Thanigaimalai et al., 2010). Most of the tyrosinase inhibitors are phenol/catechol derivatives, structurally similar to tyrosine or L-DOPA, which act as suicide substrates of tyrosinase (Passi & Nazzaro-Porro, 1981). However, most of them are not potent enough to put into practical use due to their weak individual activities or safety concerns. Undoubtedly, it is required to search and develop novel tyrosinase inhibitors with better activities together with lower side effects. In continuing our research on the development of tyrosinase inhibitors for new whitening agents, we have synthesized the title compound, (I), from the reaction of 2-(4-hydroxyphenyl)ethyl amine and 2,5-dimethoxyphenyl isocyanate under ambient condition. Here, we report the crystal structure of the title compound, (I).
The 2,5-dimethoxyphenyl moiety is almost planar with r.m.s. deviation of 0.015 Å from the corresponding least-squares plane defined by the nine constituent atoms. The dihedral angle between the phenyl ring and the plane of urea moiety is 20.95 (8) °. The molecular structure is stabilized by a short intramolecular N7—H7···O20 hydrogen bond (Fig. 1). In the crystal, intermolecular N—H···O and O—H···O hydrogen bonds link the molecules into a three-dimensional network (Fig. 2, Table 1). The H atoms of the NH groups of urea are positioned syn to each other.