N-(3,4-Difluoro­phen­yl)-2-(3,4-dimethoxy­phen­yl)acetamide

Hong, W.K.; Lee, Y.-S.; Han, B.H.; Kang, S.K.; Sung, C.K.

doi:10.1107/S1600536808003590

organic compounds

CRYSTALLOGRAPHIC
COMMUNICATIONS

ISSN: 2056-9890

Volume 64| Part 3| March 2008| Page o564

doi:10.1107/S1600536808003590

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N-(3,4-Difluorophenyl)-2-(3,4-dimethoxyphenyl)acetamide

Won Ki Hong,^a You-Soon Lee,^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 9 January 2008; accepted 1 February 2008; online 6 February 2008)

In the title amide, C₁₆H₁₅F₂NO₃, the dihedral angle between the benzene rings is 53.7 (1)°. Molecules are linked in the crystal structure by an intermolecular N—H⋯O hydrogen bond involving N—H and C=O functionalities of the amide group. A one-dimensional network is thus formed along the [001] direction. No significant interchain contacts are observed.

Related literature

For general background, see: Maeda et al. (1991 ); Dawley et al. (1993 ); Nerya et al. (2003 ); Lee et al. (2007 ); Ha et al. (2007 ); Hong et al. (2008 ); Yan et al. (2007 ).

Experimental

Crystal data

C₁₆H₁₅F₂NO₃
M_r = 307.29
Monoclinic, P 2₁ /c
a = 8.6440 (11) Å
b = 18.867 (6) Å
c = 9.4827 (13) Å
β = 111.019 (11)°
V = 1443.6 (5) Å³
Z = 4
Mo Kα radiation
μ = 0.12 mm⁻¹
T = 295 (2) K
0.26 × 0.26 × 0.23 mm

Data collection

Enraf–Nonius CAD-4 diffractometer
Absorption correction: none
2855 measured reflections
2689 independent reflections
1089 reflections with I > 2σ(I)
R_int = 0.050
3 standard reflections every 400 reflections intensity decay: 3%

Refinement

R[F² > 2σ(F²)] = 0.076
wR(F²) = 0.161
S = 0.99
2689 reflections
203 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.19 e Å⁻³
Δρ_min = −0.19 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N7—H7⋯O9ⁱ	0.89 (5)	1.98 (5)	2.846 (5)	163 (5)
Symmetry code: (i) $[x, -y+{\script{3\over 2}}, z-{\script{1\over 2}}]$ .

Data collection: CAD-4 EXPRESS (Enraf–Nonius, 1994 ); cell refinement: CAD-4 EXPRESS; data reduction: XCAD4 (Harms & Wocadlo, 1995 ); 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/S1600536808003590/bh2160sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536808003590/bh2160Isup2.hkl

checkCIF report

Comment top

Tyrosinase is the key enzyme (Ha et al., 2007) that converts tyrosine to melanin, and its inhibitors are the target molecules to develop and research anti-pigmentation agents for application to skin. The melanin formation is also accelerated by exposure under sunlight, especially U.V. (Ha et al., 2007; Yan et al., 2007). Therefore, treatments using potent inhibitory agents on tyrosinase and melanin formation may be cosmetically useful. Most of the whitening agents (Maeda et al., 1991; Dawley et al., 1993; Nerya et al., 2003) contain hydroxyl (Hong et al., 2008; Lee et al., 2007), aromatic, alkene, carbonyl, and ether groups in their structure, and act as a specific functional group to make the skin white by inhibiting the production of melanin.

During our work on developing potent whiting agents, in order to prevent the inadequacies of current whitening agents (poor skin penetration and toxicity) and maximize the inhibitory effects of melanin creation, we synthesized the title compound, (I), via a general chemical reaction, and studied its X-ray crystal structure.

The 3,4-dimethoxyphenyl moiety and 3,4-difluoroaniline group are essentially planar, with a mean deviation of 0.005 and 0.006 Å, respectively, from the corresponding least-squares planes. The dihedral angle between the benzene rings is 53.7 (1)°. The intermolecular N7—H7···O9ⁱ (symmetry code: (i) x, -y + 3/2, z - 1/2) hydrogen bond (involving the H atom of the amine and O atom of carbonyl) allows to form an extensive one-dimensional network along the c-axis, which stabilizes the crystal structure.

Related literature top

For general background see: Maeda et al. (1991); Dawley et al. (1993); Nerya et al. (2003); Lee et al. (2007); Ha et al. (2007); Hong et al. (2008); Yan et al. (2007).

Experimental top

3,4-Difluoroaniline and 3,4-dimethoxy phenyl acetyl chloride were purchased from Sigma Chemicals Co. Solvents used for organic synthesis were distilled before use. All other chemicals and solvents were of analytical grade and used without further purification. The title compound was prepared from the reaction of 3,4-difluoroaniline (1 mmol) and 3,4-dimethoxy phenyl acetyl chloride (1.2 mmol) by simple substitution (nucleophilic addition-elimination on carbonyl C atom) in THF. Removal of solvent gave a white solid. The solid was purified by column chromatography on silica gel (2:1 hexane/ethyl acetate) to give the title compound (92% yield). Colourless crystals (m.p. 393 K) were obtained by slow evaporation of an ethyl acetate solution at 298 K.

Computing details top

Data collection: CAD-4 EXPRESS (Enraf–Nonius, 1994); cell refinement: CAD-4 EXPRESS (Enraf–Nonius, 1994); data reduction: XCAD4 (Harms & Wocadlo, 1995); 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. The molecular structure of the title compound, showing the atom-numbering scheme and 30% probability ellipsoids.

N-(3,4-Difluorophenyl)-2-(3,4-dimethoxyphenyl)acetamide top

Crystal data top

C₁₆H₁₅F₂NO₃	F(000) = 640
M_r = 307.29	D_x = 1.414 Mg m⁻³
Monoclinic, P2₁/c	Melting point: 393 K
Hall symbol: -P 2ybc	Mo Kα radiation, λ = 0.71073 Å
a = 8.6440 (11) Å	Cell parameters from 25 reflections
b = 18.867 (6) Å	θ = 10.0–13.5°
c = 9.4827 (13) Å	µ = 0.12 mm⁻¹
β = 111.019 (11)°	T = 295 K
V = 1443.6 (5) Å³	Block, colourless
Z = 4	0.26 × 0.26 × 0.23 mm

Data collection top

Enraf–Nonius CAD-4 diffractometer	θ_max = 25.5°, θ_min = 2.2°
non–profiled ω/2θ scans	h = −10→9
2855 measured reflections	k = 0→22
2689 independent reflections	l = 0→11
1089 reflections with I > 2σ(I)	3 standard reflections every 400 reflections
R_int = 0.050	intensity decay: 3%

Refinement top

Refinement on F²	0 restraints
Least-squares matrix: full	H atoms treated by a mixture of independent and constrained refinement
R[F² > 2σ(F²)] = 0.076	w = 1/[σ²(F_o²) + (0.0403P)²] where P = (F_o² + 2F_c²)/3
wR(F²) = 0.161	(Δ/σ)_max < 0.001
S = 1.00	Δρ_max = 0.19 e Å⁻³
2689 reflections	Δρ_min = −0.19 e Å⁻³
203 parameters

Crystal data top

C₁₆H₁₅F₂NO₃	V = 1443.6 (5) Å³
M_r = 307.29	Z = 4
Monoclinic, P2₁/c	Mo Kα radiation
a = 8.6440 (11) Å	µ = 0.12 mm⁻¹
b = 18.867 (6) Å	T = 295 K
c = 9.4827 (13) Å	0.26 × 0.26 × 0.23 mm
β = 111.019 (11)°

Data collection top

Enraf–Nonius CAD-4 diffractometer	R_int = 0.050
2855 measured reflections	3 standard reflections every 400 reflections
2689 independent reflections	intensity decay: 3%
1089 reflections with I > 2σ(I)

Refinement top

R[F² > 2σ(F²)] = 0.076	0 restraints
wR(F²) = 0.161	H atoms treated by a mixture of independent and constrained refinement
S = 1.00	Δρ_max = 0.19 e Å⁻³
2689 reflections	Δρ_min = −0.19 e Å⁻³
203 parameters

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

	x	y	z	U_iso*/U_eq
C1	0.1632 (6)	0.6519 (2)	−0.2444 (5)	0.0423 (12)
C2	0.0544 (6)	0.6516 (3)	−0.3939 (5)	0.0492 (13)
H2	0.0578	0.6871	−0.4606	0.059*
C3	−0.0570 (7)	0.5976 (3)	−0.4396 (6)	0.0581 (15)
C4	−0.0637 (7)	0.5447 (3)	−0.3452 (6)	0.0593 (15)
C5	0.0438 (7)	0.5443 (3)	−0.1995 (6)	0.0671 (17)
H5	0.0407	0.5079	−0.1346	0.081*
C6	0.1575 (6)	0.5985 (3)	−0.1487 (5)	0.0531 (14)
H6	0.2306	0.5988	−0.0489	0.064*
F1	−0.1663 (4)	0.59760 (17)	−0.5842 (3)	0.0941 (12)
F2	−0.1777 (4)	0.49215 (17)	−0.3968 (4)	0.0917 (12)
N7	0.2760 (5)	0.7098 (2)	−0.2001 (4)	0.0446 (11)
H7	0.304 (6)	0.729 (3)	−0.273 (5)	0.08 (2)*
C8	0.3307 (6)	0.7408 (3)	−0.0639 (5)	0.0418 (12)
O9	0.2978 (4)	0.71902 (17)	0.0431 (3)	0.0608 (11)
C10	0.4341 (6)	0.8066 (3)	−0.0549 (5)	0.0566 (15)
H10A	0.5055	0.7986	−0.1122	0.068*
H10B	0.3607	0.8457	−0.1019	0.068*
C11	0.5399 (6)	0.8276 (3)	0.1044 (5)	0.0464 (13)
C12	0.5239 (6)	0.8935 (3)	0.1612 (5)	0.0502 (14)
H12	0.4463	0.9254	0.1007	0.06*
C13	0.6219 (6)	0.9127 (3)	0.3069 (5)	0.0490 (14)
C14	0.7395 (6)	0.8654 (3)	0.3968 (5)	0.0498 (13)
C15	0.7552 (6)	0.8002 (3)	0.3398 (5)	0.0611 (16)
H15	0.8334	0.7682	0.3993	0.073*
C16	0.6557 (6)	0.7815 (3)	0.1945 (6)	0.0599 (15)
H16	0.6677	0.737	0.1575	0.072*
O17	0.6123 (4)	0.97621 (19)	0.3725 (4)	0.0741 (12)
C18	0.4880 (7)	1.0251 (3)	0.2884 (6)	0.0797 (19)
H18A	0.4946	1.0671	0.3474	0.12*
H18B	0.3807	1.0039	0.2643	0.12*
H18C	0.505	1.0373	0.1968	0.12*
O19	0.8299 (4)	0.88921 (18)	0.5388 (4)	0.0679 (11)
C20	0.9656 (6)	0.8464 (3)	0.6292 (5)	0.0686 (17)
H20A	1.0195	0.869	0.7251	0.103*
H20B	1.0431	0.8408	0.5786	0.103*
H20C	0.9252	0.8008	0.6446	0.103*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
C1	0.047 (3)	0.043 (3)	0.037 (3)	0.001 (3)	0.015 (2)	−0.006 (2)
C2	0.054 (3)	0.045 (3)	0.039 (3)	0.000 (3)	0.006 (3)	0.006 (2)
C3	0.060 (4)	0.062 (4)	0.040 (3)	0.001 (3)	0.004 (3)	−0.013 (3)
C4	0.061 (4)	0.053 (4)	0.060 (4)	−0.007 (3)	0.018 (3)	−0.010 (3)
C5	0.092 (5)	0.043 (4)	0.066 (4)	−0.010 (3)	0.028 (4)	0.001 (3)
C6	0.067 (4)	0.047 (3)	0.040 (3)	0.002 (3)	0.012 (3)	0.006 (3)
F1	0.087 (3)	0.103 (3)	0.062 (2)	−0.025 (2)	−0.0110 (18)	−0.010 (2)
F2	0.093 (3)	0.073 (2)	0.103 (3)	−0.036 (2)	0.028 (2)	−0.024 (2)
N7	0.047 (3)	0.053 (3)	0.030 (2)	−0.004 (2)	0.010 (2)	−0.003 (2)
C8	0.041 (3)	0.053 (3)	0.029 (3)	−0.002 (3)	0.010 (2)	−0.003 (3)
O9	0.078 (3)	0.073 (3)	0.0360 (19)	−0.027 (2)	0.0258 (18)	−0.0142 (18)
C10	0.056 (3)	0.066 (4)	0.045 (3)	−0.009 (3)	0.015 (3)	−0.003 (3)
C11	0.045 (3)	0.051 (3)	0.041 (3)	−0.004 (3)	0.012 (2)	−0.003 (3)
C12	0.044 (3)	0.056 (4)	0.044 (3)	−0.001 (3)	0.009 (3)	0.004 (3)
C13	0.050 (3)	0.049 (3)	0.041 (3)	0.000 (3)	0.007 (3)	−0.011 (3)
C14	0.041 (3)	0.058 (4)	0.041 (3)	−0.001 (3)	0.004 (2)	−0.006 (3)
C15	0.056 (3)	0.057 (4)	0.054 (3)	0.011 (3)	0.000 (3)	−0.014 (3)
C16	0.060 (4)	0.059 (4)	0.057 (3)	0.000 (3)	0.018 (3)	−0.009 (3)
O17	0.069 (3)	0.062 (3)	0.062 (2)	0.020 (2)	−0.012 (2)	−0.008 (2)
C18	0.074 (4)	0.059 (4)	0.083 (4)	0.016 (3)	0.000 (3)	−0.006 (3)
O19	0.062 (2)	0.070 (3)	0.048 (2)	0.019 (2)	−0.0085 (19)	−0.0103 (19)
C20	0.054 (3)	0.078 (4)	0.051 (3)	0.010 (3)	−0.009 (3)	0.000 (3)

Geometric parameters (Å, º) top

C1—C6	1.368 (6)	C11—C16	1.369 (6)
C1—C2	1.392 (6)	C11—C12	1.381 (6)
C1—N7	1.423 (6)	C12—C13	1.386 (6)
C2—C3	1.362 (6)	C12—H12	0.93
C2—H2	0.93	C13—O17	1.367 (5)
C3—C4	1.356 (7)	C13—C14	1.390 (6)
C3—F1	1.357 (5)	C14—O19	1.368 (5)
C4—F2	1.359 (5)	C14—C15	1.370 (6)
C4—C5	1.361 (6)	C15—C16	1.383 (6)
C5—C6	1.380 (6)	C15—H15	0.93
C5—H5	0.93	C16—H16	0.93
C6—H6	0.93	O17—C18	1.423 (5)
N7—C8	1.340 (5)	C18—H18A	0.96
N7—H7	0.89 (5)	C18—H18B	0.96
C8—O9	1.219 (5)	C18—H18C	0.96
C8—C10	1.515 (6)	O19—C20	1.428 (5)
C10—C11	1.511 (6)	C20—H20A	0.96
C10—H10A	0.97	C20—H20B	0.96
C10—H10B	0.97	C20—H20C	0.96

C6—C1—C2	120.0 (5)	C16—C11—C10	120.2 (5)
C6—C1—N7	123.6 (4)	C12—C11—C10	121.0 (4)
C2—C1—N7	116.4 (4)	C11—C12—C13	120.9 (5)
C3—C2—C1	118.0 (5)	C11—C12—H12	119.6
C3—C2—H2	121	C13—C12—H12	119.6
C1—C2—H2	121	O17—C13—C12	124.6 (4)
C4—C3—F1	119.2 (5)	O17—C13—C14	115.7 (4)
C4—C3—C2	122.2 (5)	C12—C13—C14	119.7 (5)
F1—C3—C2	118.5 (5)	O19—C14—C15	125.5 (4)
C3—C4—F2	119.8 (5)	O19—C14—C13	115.3 (4)
C3—C4—C5	119.9 (5)	C15—C14—C13	119.2 (4)
F2—C4—C5	120.4 (5)	C14—C15—C16	120.5 (5)
C4—C5—C6	119.5 (5)	C14—C15—H15	119.7
C4—C5—H5	120.2	C16—C15—H15	119.7
C6—C5—H5	120.2	C11—C16—C15	120.9 (5)
C1—C6—C5	120.3 (5)	C11—C16—H16	119.5
C1—C6—H6	119.9	C15—C16—H16	119.5
C5—C6—H6	119.9	C13—O17—C18	118.1 (4)
C8—N7—C1	125.9 (4)	O17—C18—H18A	109.5
C8—N7—H7	118 (3)	O17—C18—H18B	109.5
C1—N7—H7	116 (3)	H18A—C18—H18B	109.5
O9—C8—N7	123.3 (5)	O17—C18—H18C	109.5
O9—C8—C10	122.6 (4)	H18A—C18—H18C	109.5
N7—C8—C10	114.1 (4)	H18B—C18—H18C	109.5
C11—C10—C8	113.8 (4)	C14—O19—C20	117.5 (4)
C11—C10—H10A	108.8	O19—C20—H20A	109.5
C8—C10—H10A	108.8	O19—C20—H20B	109.5
C11—C10—H10B	108.8	H20A—C20—H20B	109.5
C8—C10—H10B	108.8	O19—C20—H20C	109.5
H10A—C10—H10B	107.7	H20A—C20—H20C	109.5
C16—C11—C12	118.8 (4)	H20B—C20—H20C	109.5

C6—C1—C2—C3	0.8 (7)	C8—C10—C11—C16	59.3 (6)
N7—C1—C2—C3	−178.9 (4)	C8—C10—C11—C12	−121.7 (5)
C1—C2—C3—C4	−0.6 (8)	C16—C11—C12—C13	−0.6 (7)
C1—C2—C3—F1	178.5 (4)	C10—C11—C12—C13	−179.5 (4)
F1—C3—C4—F2	0.8 (8)	C11—C12—C13—O17	−178.9 (5)
C2—C3—C4—F2	179.9 (5)	C11—C12—C13—C14	0.8 (7)
F1—C3—C4—C5	−179.3 (5)	O17—C13—C14—O19	−0.2 (7)
C2—C3—C4—C5	−0.2 (9)	C12—C13—C14—O19	−180.0 (4)
C3—C4—C5—C6	0.8 (8)	O17—C13—C14—C15	179.1 (5)
F2—C4—C5—C6	−179.3 (5)	C12—C13—C14—C15	−0.6 (8)
C2—C1—C6—C5	−0.2 (7)	O19—C14—C15—C16	179.4 (5)
N7—C1—C6—C5	179.5 (5)	C13—C14—C15—C16	0.2 (8)
C4—C5—C6—C1	−0.6 (8)	C12—C11—C16—C15	0.1 (8)
C6—C1—N7—C8	−34.1 (7)	C10—C11—C16—C15	179.1 (5)
C2—C1—N7—C8	145.6 (5)	C14—C15—C16—C11	0.1 (8)
C1—N7—C8—O9	5.3 (8)	C12—C13—O17—C18	3.0 (7)
C1—N7—C8—C10	−173.2 (4)	C14—C13—O17—C18	−176.8 (5)
O9—C8—C10—C11	20.3 (7)	C15—C14—O19—C20	8.1 (8)
N7—C8—C10—C11	−161.2 (4)	C13—C14—O19—C20	−172.6 (4)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N7—H7···O9ⁱ	0.89 (5)	1.98 (5)	2.846 (5)	163 (5)

Symmetry code: (i) x, −y+3/2, z−1/2.

Experimental details

Crystal data
Chemical formula	C₁₆H₁₅F₂NO₃
M_r	307.29
Crystal system, space group	Monoclinic, P2₁/c
Temperature (K)	295
a, b, c (Å)	8.6440 (11), 18.867 (6), 9.4827 (13)
β (°)	111.019 (11)
V (Å³)	1443.6 (5)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.12
Crystal size (mm)	0.26 × 0.26 × 0.23

Data collection
Diffractometer	Enraf–Nonius CAD-4 diffractometer
Absorption correction	–
No. of measured, independent and observed [I > 2σ(I)] reflections	2855, 2689, 1089
R_int	0.050
(sin θ/λ)_max (Å⁻¹)	0.606

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.076, 0.161, 1.00
No. of reflections	2689
No. of parameters	203
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.19, −0.19

Computer programs: CAD-4 EXPRESS (Enraf–Nonius, 1994), XCAD4 (Harms & Wocadlo, 1995), 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
N7—H7···O9ⁱ	0.89 (5)	1.98 (5)	2.846 (5)	163 (5)

Symmetry code: (i) x, −y+3/2, z−1/2.

Acknowledgements

The X-ray data were collected at the Center for Research Facilities, Chungnam National University. This work was partially supported by the fund of New University for Regional Innovation (grant No. 05-Na-A-01) from the Ministry of Education and Human Resources Department, Republic of Korea.

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