organic compounds
1-(2-Hydroxy-2-phenylethyl)-3-(4-methoxyphenyl)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, C16H18N2O3, the dihedral angle between the 4-methoxyphenyl ring and the urea group is 35.6 (2) °. The H atoms of the urea NH groups are positioned syn to each other. In the crystal, intermolecular N—H⋯O and O—H⋯O hydrogen bonds link the molecules into a two-dimensional array in the ac plane; the carbonyl-O atom is trifurcated.
Related literature
For general background to melanin, see: Prota (1988). For the development of potent inhibitory agents of tyrosinase, see: Khan et al. (2006); Kojima et al. (1995); Cabanes et al. (1994); Son et al. (2000); Iida et al. (1995).
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: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX publication routines (Farrugia, 1999).
Supporting information
https://doi.org/10.1107/S1600536811036464/tk2785sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536811036464/tk2785Isup2.hkl
Supporting information file. DOI: https://doi.org/10.1107/S1600536811036464/tk2785Isup3.cml
2-Amino-1-phenylethanol and 4-methoxyphenyl isocyanate were purchased from Sigma Chemical Co. All other chemicals and solvents were of analytical grade and were used without further purification. The title compound (I) was prepared from the reaction of 2-amino-1-phenylethanol (0.3 g, 1.2 mmol) with 4-methoxyphenyl isocyanate (0.39 g, 1.0 mmol) in acetonitrile (6 ml) with stirring. The reaction was completed within 1 h at room temperature. The solvents were removed under reduced pressure, collected and washed with dichloromethane. Removal of the solvent gave a white solid (84%; M.pt 468 K). Colourless crystals of (I) were obtained from its ethanolic solution by slow evaporation of the solvent at room temperature.
The NH H atoms were located in a difference Fourier map and refined freely. The OH H atom was located in a difference Fourier map and refined with Uiso(H) = 1.2Ueq(O). 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 methylene, and 1.5Ueq(C) for methyl H atoms. In the absence of significant
effects, 578 Friedel pairs were averaged in the final The maximum and minimum residual electron density peaks of 0.71 and -0.26 eÅ-3, respectively, were located at 0.99 Å and 0.42 Å from the C7 and H7 atoms, respectively.Melanin is one of the most widely distributed pigments and is found in bacteria, fungi, plants and animals. It is a heterogeneous polyphenol-like biopolymer with a complex structure and colour varying from yellow to black (Prota, 1988). Tyrosinase inhibitors are clinically useful for the treatment of some dermatological disorders associated with melanin hyperpigmentation and are also important in the cosmetic industry for whitening and depigmentation after sunburn (Khan et al., 2006). Numerous potential tyrosinase inhibitors have been discovered from natural and synthetic sources, such as ascorbic acid (Kojima et al., 1995), kojic acid (Cabanes et al., 1994), and tropolone (Son et al., 2000; Iida et al., 1995). 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-amino-1-phenylethanol and 4-methoxyphenyl isocyanate under ambient conditions. Herein, the
of (I) is described (Fig. 1).The 4-methoxyphenyl unit is almost planar, with an r.m.s. deviation of 0.031 Å from the least-squares plane defined by the eight constituent atoms. The dihedral angle between the 4-methoxyphenyl ring and the urea plane is 35.6 (2) °. The H atoms of the urea NH groups are positioned syn to each other. The presence of intermolecular N—H···O and O—H···O hydrogen bonds link the molecules into a two-dimensional array in the ac plane (Fig. 2, Table 1). The urea-O accepts three hydrogen bonds, one from –OH and two from –NH groups.
For general background to melanin, see: Prota (1988). For the development of potent inhibitory agents of tyrosinase, see: Khan et al. (2006); Kojima et al. (1995); Cabanes et al. (1994); Son et al. (2000); Iida et al. (1995).
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: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX publication routines (Farrugia, 1999).C16H18N2O3 | F(000) = 304 |
Mr = 286.32 | Dx = 1.322 Mg m−3 |
Monoclinic, P21 | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: P 2yb | Cell parameters from 4535 reflections |
a = 6.8120 (6) Å | θ = 2.9–28.1° |
b = 8.7659 (7) Å | µ = 0.09 mm−1 |
c = 12.1393 (10) Å | T = 296 K |
β = 97.009 (3)° | Block, colourless |
V = 719.46 (10) Å3 | 0.07 × 0.05 × 0.03 mm |
Z = 2 |
Bruker SMART CCD area-detector diffractometer | Rint = 0.073 |
Graphite monochromator | θmax = 25.5°, θmin = 1.7° |
φ and ω scans | h = −7→8 |
5017 measured reflections | k = −5→10 |
1947 independent reflections | l = −7→14 |
1782 reflections with I > 2σ(I) |
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)] = 0.060 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.166 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.05 | w = 1/[σ2(Fo2) + (0.0819P)2 + 0.6912P] where P = (Fo2 + 2Fc2)/3 |
1947 reflections | (Δ/σ)max < 0.001 |
201 parameters | Δρmax = 0.71 e Å−3 |
1 restraint | Δρmin = −0.26 e Å−3 |
C16H18N2O3 | V = 719.46 (10) Å3 |
Mr = 286.32 | Z = 2 |
Monoclinic, P21 | Mo Kα radiation |
a = 6.8120 (6) Å | µ = 0.09 mm−1 |
b = 8.7659 (7) Å | T = 296 K |
c = 12.1393 (10) Å | 0.07 × 0.05 × 0.03 mm |
β = 97.009 (3)° |
Bruker SMART CCD area-detector diffractometer | 1782 reflections with I > 2σ(I) |
5017 measured reflections | Rint = 0.073 |
1947 independent reflections |
R[F2 > 2σ(F2)] = 0.060 | 1 restraint |
wR(F2) = 0.166 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.05 | Δρmax = 0.71 e Å−3 |
1947 reflections | Δρmin = −0.26 e Å−3 |
201 parameters |
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. |
x | y | z | Uiso*/Ueq | ||
C1 | 0.3090 (6) | 0.9178 (6) | −0.2016 (4) | 0.0461 (12) | |
C2 | 0.2104 (7) | 0.7832 (7) | −0.1959 (4) | 0.0533 (14) | |
H2 | 0.2401 | 0.7201 | −0.1345 | 0.064* | |
C3 | 0.0666 (8) | 0.7396 (7) | −0.2805 (4) | 0.0542 (13) | |
H3 | 0.0017 | 0.6469 | −0.2758 | 0.065* | |
C4 | 0.0191 (7) | 0.8310 (7) | −0.3707 (4) | 0.0505 (13) | |
H4 | −0.0787 | 0.8012 | −0.4268 | 0.061* | |
C5 | 0.1151 (7) | 0.9660 (7) | −0.3783 (4) | 0.0530 (14) | |
H5 | 0.0838 | 1.0293 | −0.4394 | 0.064* | |
C6 | 0.2616 (7) | 1.0081 (7) | −0.2929 (5) | 0.0571 (14) | |
H6 | 0.3285 | 1.0998 | −0.2983 | 0.069* | |
C7 | 0.4712 (7) | 0.9574 (7) | −0.1086 (5) | 0.0613 (16) | |
H7 | 0.4519 | 0.8924 | −0.0451 | 0.074* | |
O8 | 0.4713 (6) | 1.1060 (5) | −0.0726 (3) | 0.0631 (11) | |
H8 | 0.347 (10) | 1.118 (8) | −0.071 (5) | 0.076* | |
C9 | 0.6694 (6) | 0.9180 (6) | −0.1428 (3) | 0.0378 (10) | |
H9A | 0.6796 | 0.8079 | −0.1485 | 0.045* | |
H9B | 0.6782 | 0.9604 | −0.2159 | 0.045* | |
N10 | 0.8347 (5) | 0.9736 (5) | −0.0668 (3) | 0.0369 (9) | |
H10 | 0.876 (8) | 1.060 (7) | −0.072 (4) | 0.052 (17)* | |
C11 | 0.9310 (5) | 0.8900 (5) | 0.0159 (3) | 0.0309 (9) | |
O12 | 0.8885 (4) | 0.7545 (3) | 0.0342 (2) | 0.0365 (7) | |
N13 | 1.0818 (5) | 0.9640 (5) | 0.0765 (3) | 0.0345 (8) | |
H13 | 1.108 (7) | 1.048 (7) | 0.060 (4) | 0.036 (14)* | |
C14 | 1.2036 (6) | 0.9091 (5) | 0.1709 (3) | 0.0305 (9) | |
C15 | 1.3978 (6) | 0.9599 (5) | 0.1905 (3) | 0.0351 (10) | |
H15 | 1.4482 | 1.0223 | 0.1387 | 0.042* | |
C16 | 1.5166 (6) | 0.9188 (5) | 0.2859 (3) | 0.0349 (10) | |
H16 | 1.6459 | 0.9546 | 0.2983 | 0.042* | |
C17 | 1.4460 (6) | 0.8252 (5) | 0.3630 (3) | 0.0345 (10) | |
C18 | 1.2540 (6) | 0.7706 (6) | 0.3442 (3) | 0.0383 (10) | |
H18 | 1.2069 | 0.705 | 0.3951 | 0.046* | |
C19 | 1.1310 (6) | 0.8140 (5) | 0.2487 (3) | 0.0369 (10) | |
H19 | 1.001 | 0.7795 | 0.237 | 0.044* | |
O20 | 1.5764 (4) | 0.7926 (4) | 0.4554 (2) | 0.0435 (9) | |
C21 | 1.5099 (8) | 0.6908 (7) | 0.5350 (4) | 0.0520 (13) | |
H21A | 1.6131 | 0.6768 | 0.5954 | 0.078* | |
H21B | 1.4764 | 0.5942 | 0.5005 | 0.078* | |
H21C | 1.3954 | 0.7331 | 0.5626 | 0.078* |
U11 | U22 | U33 | U12 | U13 | U23 | |
C1 | 0.029 (2) | 0.051 (3) | 0.057 (3) | 0.014 (2) | 0.0003 (18) | −0.010 (3) |
C2 | 0.045 (3) | 0.067 (4) | 0.048 (2) | 0.015 (3) | 0.010 (2) | 0.003 (3) |
C3 | 0.042 (3) | 0.054 (3) | 0.069 (3) | −0.007 (2) | 0.016 (2) | 0.004 (3) |
C4 | 0.029 (2) | 0.071 (4) | 0.049 (2) | −0.004 (2) | −0.0010 (18) | −0.006 (3) |
C5 | 0.041 (3) | 0.062 (4) | 0.056 (3) | 0.013 (3) | 0.008 (2) | 0.014 (3) |
C6 | 0.035 (3) | 0.044 (3) | 0.094 (4) | 0.000 (2) | 0.015 (3) | −0.002 (3) |
C7 | 0.044 (3) | 0.070 (4) | 0.067 (3) | 0.006 (3) | −0.002 (2) | −0.025 (3) |
O8 | 0.0414 (18) | 0.065 (3) | 0.080 (2) | 0.0104 (19) | −0.0049 (17) | −0.033 (2) |
C9 | 0.029 (2) | 0.040 (3) | 0.042 (2) | 0.0025 (19) | −0.0037 (16) | −0.006 (2) |
N10 | 0.0314 (19) | 0.034 (2) | 0.0427 (19) | −0.0011 (17) | −0.0043 (14) | −0.0009 (18) |
C11 | 0.0236 (18) | 0.033 (2) | 0.0371 (19) | 0.0026 (17) | 0.0090 (15) | −0.0025 (19) |
O12 | 0.0340 (15) | 0.0310 (18) | 0.0438 (15) | −0.0032 (13) | 0.0016 (11) | −0.0008 (13) |
N13 | 0.0353 (19) | 0.031 (2) | 0.0355 (17) | −0.0055 (17) | −0.0031 (14) | 0.0057 (17) |
C14 | 0.030 (2) | 0.030 (2) | 0.0311 (18) | −0.0019 (18) | 0.0014 (15) | −0.0015 (18) |
C15 | 0.037 (2) | 0.037 (3) | 0.0305 (18) | −0.006 (2) | 0.0044 (15) | −0.0015 (19) |
C16 | 0.031 (2) | 0.039 (3) | 0.0342 (19) | −0.0056 (19) | 0.0017 (15) | −0.0048 (19) |
C17 | 0.039 (2) | 0.035 (2) | 0.0292 (18) | 0.004 (2) | 0.0013 (16) | −0.0045 (19) |
C18 | 0.038 (2) | 0.043 (3) | 0.0347 (19) | −0.005 (2) | 0.0052 (16) | 0.007 (2) |
C19 | 0.029 (2) | 0.040 (3) | 0.041 (2) | −0.0039 (19) | 0.0045 (16) | 0.000 (2) |
O20 | 0.0412 (17) | 0.049 (2) | 0.0375 (15) | −0.0036 (15) | −0.0045 (12) | 0.0146 (15) |
C21 | 0.049 (3) | 0.065 (4) | 0.041 (2) | −0.003 (3) | −0.001 (2) | 0.021 (2) |
C1—C2 | 1.363 (8) | N10—H10 | 0.81 (6) |
C1—C6 | 1.369 (7) | C11—O12 | 1.249 (5) |
C1—C7 | 1.520 (7) | C11—N13 | 1.354 (5) |
C2—C3 | 1.384 (7) | N13—C14 | 1.415 (5) |
C2—H2 | 0.93 | N13—H13 | 0.79 (5) |
C3—C4 | 1.364 (8) | C14—C15 | 1.389 (5) |
C3—H3 | 0.93 | C14—C19 | 1.395 (6) |
C4—C5 | 1.361 (8) | C15—C16 | 1.377 (6) |
C4—H4 | 0.93 | C15—H15 | 0.93 |
C5—C6 | 1.398 (7) | C16—C17 | 1.375 (6) |
C5—H5 | 0.93 | C16—H16 | 0.93 |
C6—H6 | 0.93 | C17—O20 | 1.374 (4) |
C7—O8 | 1.374 (7) | C17—C18 | 1.385 (6) |
C7—C9 | 1.501 (7) | C18—C19 | 1.398 (6) |
C7—H7 | 0.98 | C18—H18 | 0.93 |
O8—H8 | 0.86 (7) | C19—H19 | 0.93 |
C9—N10 | 1.450 (5) | O20—C21 | 1.429 (6) |
C9—H9A | 0.97 | C21—H21A | 0.96 |
C9—H9B | 0.97 | C21—H21B | 0.96 |
N10—C11 | 1.347 (5) | C21—H21C | 0.96 |
C2—C1—C6 | 118.2 (4) | C9—N10—H10 | 121 (4) |
C2—C1—C7 | 118.5 (5) | O12—C11—N10 | 123.2 (4) |
C6—C1—C7 | 123.2 (5) | O12—C11—N13 | 122.4 (4) |
C1—C2—C3 | 120.7 (5) | N10—C11—N13 | 114.4 (4) |
C1—C2—H2 | 119.7 | C11—N13—C14 | 127.5 (4) |
C3—C2—H2 | 119.7 | C11—N13—H13 | 119 (3) |
C4—C3—C2 | 120.7 (5) | C14—N13—H13 | 113 (3) |
C4—C3—H3 | 119.6 | C15—C14—C19 | 119.0 (3) |
C2—C3—H3 | 119.6 | C15—C14—N13 | 118.8 (4) |
C5—C4—C3 | 119.8 (5) | C19—C14—N13 | 122.0 (3) |
C5—C4—H4 | 120.1 | C16—C15—C14 | 120.7 (4) |
C3—C4—H4 | 120.1 | C16—C15—H15 | 119.7 |
C4—C5—C6 | 119.0 (5) | C14—C15—H15 | 119.7 |
C4—C5—H5 | 120.5 | C17—C16—C15 | 120.7 (4) |
C6—C5—H5 | 120.5 | C17—C16—H16 | 119.7 |
C1—C6—C5 | 121.6 (5) | C15—C16—H16 | 119.7 |
C1—C6—H6 | 119.2 | O20—C17—C16 | 115.8 (4) |
C5—C6—H6 | 119.2 | O20—C17—C18 | 124.5 (4) |
O8—C7—C9 | 109.9 (5) | C16—C17—C18 | 119.7 (3) |
O8—C7—C1 | 115.1 (4) | C17—C18—C19 | 120.1 (4) |
C9—C7—C1 | 109.8 (4) | C17—C18—H18 | 120 |
O8—C7—H7 | 107.2 | C19—C18—H18 | 120 |
C9—C7—H7 | 107.2 | C14—C19—C18 | 119.8 (4) |
C1—C7—H7 | 107.2 | C14—C19—H19 | 120.1 |
C7—O8—H8 | 100 (5) | C18—C19—H19 | 120.1 |
N10—C9—C7 | 113.6 (4) | C17—O20—C21 | 117.1 (3) |
N10—C9—H9A | 108.8 | O20—C21—H21A | 109.5 |
C7—C9—H9A | 108.8 | O20—C21—H21B | 109.5 |
N10—C9—H9B | 108.8 | H21A—C21—H21B | 109.5 |
C7—C9—H9B | 108.8 | O20—C21—H21C | 109.5 |
H9A—C9—H9B | 107.7 | H21A—C21—H21C | 109.5 |
C11—N10—C9 | 124.1 (4) | H21B—C21—H21C | 109.5 |
C11—N10—H10 | 115 (4) |
D—H···A | D—H | H···A | D···A | D—H···A |
O8—H8···O12i | 0.86 (7) | 2.09 (7) | 2.863 (5) | 150 (6) |
N10—H10···O12ii | 0.81 (6) | 2.35 (6) | 3.098 (5) | 153 (5) |
N13—H13···O12ii | 0.79 (5) | 2.14 (5) | 2.898 (5) | 161 (4) |
Symmetry codes: (i) −x+1, y+1/2, −z; (ii) −x+2, y+1/2, −z. |
Experimental details
Crystal data | |
Chemical formula | C16H18N2O3 |
Mr | 286.32 |
Crystal system, space group | Monoclinic, P21 |
Temperature (K) | 296 |
a, b, c (Å) | 6.8120 (6), 8.7659 (7), 12.1393 (10) |
β (°) | 97.009 (3) |
V (Å3) | 719.46 (10) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 0.09 |
Crystal size (mm) | 0.07 × 0.05 × 0.03 |
Data collection | |
Diffractometer | Bruker SMART CCD area-detector |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 5017, 1947, 1782 |
Rint | 0.073 |
(sin θ/λ)max (Å−1) | 0.606 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.060, 0.166, 1.05 |
No. of reflections | 1947 |
No. of parameters | 201 |
No. of restraints | 1 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.71, −0.26 |
Computer programs: SMART (Bruker, 2002), SAINT (Bruker, 2002), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), ORTEP-3 for Windows (Farrugia, 1997), WinGX publication routines (Farrugia, 1999).
D—H···A | D—H | H···A | D···A | D—H···A |
O8—H8···O12i | 0.86 (7) | 2.09 (7) | 2.863 (5) | 150 (6) |
N10—H10···O12ii | 0.81 (6) | 2.35 (6) | 3.098 (5) | 153 (5) |
N13—H13···O12ii | 0.79 (5) | 2.14 (5) | 2.898 (5) | 161 (4) |
Symmetry codes: (i) −x+1, y+1/2, −z; (ii) −x+2, y+1/2, −z. |
Acknowledgements
We wish to thank the DBIO company for partial support of this work.
References
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Melanin is one of the most widely distributed pigments and is found in bacteria, fungi, plants and animals. It is a heterogeneous polyphenol-like biopolymer with a complex structure and colour varying from yellow to black (Prota, 1988). Tyrosinase inhibitors are clinically useful for the treatment of some dermatological disorders associated with melanin hyperpigmentation and are also important in the cosmetic industry for whitening and depigmentation after sunburn (Khan et al., 2006). Numerous potential tyrosinase inhibitors have been discovered from natural and synthetic sources, such as ascorbic acid (Kojima et al., 1995), kojic acid (Cabanes et al., 1994), and tropolone (Son et al., 2000; Iida et al., 1995). 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-amino-1-phenylethanol and 4-methoxyphenyl isocyanate under ambient conditions. Herein, the crystal structure of (I) is described (Fig. 1).
The 4-methoxyphenyl unit is almost planar, with an r.m.s. deviation of 0.031 Å from the least-squares plane defined by the eight constituent atoms. The dihedral angle between the 4-methoxyphenyl ring and the urea plane is 35.6 (2) °. The H atoms of the urea NH groups are positioned syn to each other. The presence of intermolecular N—H···O and O—H···O hydrogen bonds link the molecules into a two-dimensional array in the ac plane (Fig. 2, Table 1). The urea-O accepts three hydrogen bonds, one from –OH and two from –NH groups.