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Acta Crystallogr Sect E Struct Rep Online. 2008 June 1; 64(Pt 6): o1099.
Published online 2008 May 17. doi:  10.1107/S1600536808014529
PMCID: PMC2961506

N-[2-(2-Methoxyphenyl)benzylidene]-tert-butyl­amine N-oxide

Abstract

In the mol­ecule of the title compound, C18H21NO2, the two benzene rings are oriented at a dihedral angle of 58.19 (3)°. Intra­molecular C—H(...)O hydrogen bonds result in the formation of one six- and one five-membered ring, which adopt twist and envelope conformations, respectively. In the crystal structure, C—H(...)O hydrogen bonds link the mol­ecules.

Related literature

For general background, see: Hamburger & McCay (1989 [triangle]); Jotti et al. (1992 [triangle]); Murphy et al. (2003 [triangle]); Green et al. (2003 [triangle]); Durand et al. (2007 [triangle]); Hay et al. (2005 [triangle]). For related literature, see: Fevig et al. (1996 [triangle]).

An external file that holds a picture, illustration, etc.
Object name is e-64-o1099-scheme1.jpg

Experimental

Crystal data

  • C18H21NO2
  • M r = 283.37
  • Monoclinic, An external file that holds a picture, illustration, etc.
Object name is e-64-o1099-efi1.jpg
  • a = 10.2526 (15) Å
  • b = 8.5576 (13) Å
  • c = 10.3333 (16) Å
  • β = 115.742 (3)°
  • V = 816.6 (2) Å3
  • Z = 2
  • Mo Kα radiation
  • μ = 0.07 mm−1
  • T = 296 (1) K
  • 0.30 × 0.28 × 0.09 mm

Data collection

  • Rigaku R-AXIS RAPID-S diffractometer
  • Absorption correction: multi-scan (ABSCOR; Higashi, 1995 [triangle]) T min = 0.968, T max = 0.993
  • 7869 measured reflections
  • 1981 independent reflections
  • 967 reflections with F 2 > 2σ(F 2)
  • R int = 0.035

Refinement

  • R[F 2 > 2σ(F 2)] = 0.034
  • wR(F 2) = 0.058
  • S = 1.00
  • 1981 reflections
  • 191 parameters
  • H-atom parameters constrained
  • Δρmax = 0.23 e Å−3
  • Δρmin = −0.21 e Å−3

Data collection: PROCESS-AUTO (Rigaku, 1998 [triangle]); cell refinement: PROCESS-AUTO; data reduction: CrystalStructure (Rigaku/MSC, 2004 [triangle]) and Larson (1970 [triangle]); program(s) used to solve structure: SIR97 (Altomare et al., 1999 [triangle]); program(s) used to refine structure: CRYSTALS (Betteridge et al., 2003 [triangle]); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997 [triangle]); software used to prepare material for publication: CrystalStructure.

Table 1
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536808014529/hk2462sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808014529/hk2462Isup2.hkl

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Acknowledgments

This work is supported by a research grant from the Natural Science Foundation of Zhejiang Province in China (grant No. Y207295). Mr Jianming Gu and Xiurong Hu of the X-ray crystallography facility of Zhejiang University are acknowledged for their assistance with the crystal structural analysis.

supplementary crystallographic information

Comment

N-tert-Butyl-α-phenylnitrone (PBN) and its derivatives have been widely used as spin trapping agents in biology for detecting active free radicals such as oxygen- and carbon-centered radicals (Hamburger & McCay, 1989; Jotti et al., 1992; Murphy et al., 2003) and as antioxidant for treating age-related diseases (Green et al., 2003). The amphiphilic spin traps have been developed for potential use as therapeutic antioxidants (Durand et al., 2007), while the lipophilic spin traps are targeted for interception of radicals within non-aqueous phases and detection of radicals in complex biphasic biological systems (Hay et al., 2005). To explore the effect of the substituent attached to the benzene ring of PBN on the spin trapping ability, we have designed and synthesized a number of novel lipophilic spin traps derived from PBN, to which an additional aromatic group is attached.

In the molecule of (I), (Fig. 1), rings A (C2-C7) and B (C8-C13) are, of course, planar, and they are oriented at a dihedral angle of 58.19 (3)°. Unlike the N-tert-Butyl-α-phenylnitrone (Fevig et al., 1996), atoms C1, N1 and O1 is not coplanar with ring A. Intramolecular C-H···O hydrogen bonds result in the formation of one six- and one five-membered rings C (C1-C3/O1/N1/H3) and D (O1/N1/C15/C17/H171). Ring C adopts twisted conformation having total puckering amplitude, QT, of 0.443 (3) Å, while ring D has envelope conformation, with C15 atom displaced by -0.663 (3) Å from the plane of the other ring atoms.

In the crystal structure, intermolecular C-H···O hydrogen bonds link the molecules (Fig. 2), in which they may be effective in the stabilization of the structure.

Experimental

For the preparation of the title compound, activated zinc powder (195.0 mg, 3.0 mmol) was added to a solution of 2-(2-methoxyphenyl)benzaldehyde (212.0 mg, 1.0 mmol) and 2-methyl-2-nitropropane (309.0 mg, 3.0 mmol) in ethanol (95%, 15 ml) at 283 K. Glacial acetic acid (0.35 ml, 6.0 mmol) was added dropwise to the resultant suspension in 1 h with stirring. After stirring at room temperature for 12 h, the reaction mixture was kept for another 48 h in a refrigerator. It was filtered to remove the solid materials and the filtrate was concentrated under reduced pressure. The residue was purified by column chromatography on silica gel with ethylacetate and hexane (1:3) as the eluent to give the title compound (yield; 122.0 mg, 43%, m.p. 351-353 K). 1H NMR (400 MHz, CDCl3) δ: 9.43 (d, J = 8.8 Hz, 1H), 7.43-7.37 (m, 3H), 7.31 (s, 1H), 7.28-7.26 (m,1H), 7.17 (d, J = 6.4 Hz, 1H), 7.04 (t, J = 7.2 Hz, 1H), 6.98 (d, J = 8.0 Hz, 1H), 3.72 (s, 3H), 1.42 (s, 9H); 13 C NMR (100 MHz, CDCl3) δ: 156.2, 138.9, 131.5, 130.0, 129.5, 129.4, 129.2, 128.8 (2), 127.5, 127.4, 120.7 (2), 110.5, 70.6, 55.3, 28.0 (3); MS (ESI) m/z 284 (M + H). Anal. Calcd for C18H21NO2: C, 76.29; H, 7.47; N, 4.94. Found: C, 76.40; H, 7.45; N, 4.67. Single crystals of (I) suitable for X-ray analysis were grown in ethylacetate and hexane.

Refinement

H atoms were positioned geometrically, with C-H = 0.93 and 0.96 Å for aromatic and methyl H, respectively, and constrained to ride on their parent atoms with Uiso(H) = 1.2Ueq(C).

Figures

Fig. 1.
The molecular structure of the title molecule, with the atom-numbering scheme. Displacement ellipsoids are drawn at the 40% probability level.
Fig. 2.
A partial packing diagram of (I). Hydrogen bonds are shown as dashed lines.

Crystal data

C18H21NO2F000 = 304.00
Mr = 283.37Dx = 1.152 Mg m3
Monoclinic, P21Mo Kα radiation λ = 0.71075 Å
Hall symbol: P 2ybCell parameters from 4871 reflections
a = 10.2526 (15) Åθ = 3.2–27.4º
b = 8.5576 (13) ŵ = 0.08 mm1
c = 10.3333 (16) ÅT = 296 (1) K
β = 115.742 (3)ºPlatelet, colorless
V = 816.6 (2) Å30.30 × 0.28 × 0.09 mm
Z = 2

Data collection

Rigaku R-AXIS RAPID-S diffractometer967 reflections with F2 > 2σ(F2)
Detector resolution: 10.00 pixels mm-1Rint = 0.035
ω scansθmax = 27.4º
Absorption correction: multi-scan(ABSCOR; Higashi, 1995)h = −13→13
Tmin = 0.968, Tmax = 0.993k = −11→10
7869 measured reflectionsl = −13→13
1981 independent reflections

Refinement

Refinement on F2  w = 1/[1.0600σ(Fo2)]/(4Fo2)
R[F2 > 2σ(F2)] = 0.034(Δ/σ)max < 0.001
wR(F2) = 0.058Δρmax = 0.23 e Å3
S = 1.00Δρmin = −0.21 e Å3
1981 reflectionsExtinction correction: Larson (1970)
191 parametersExtinction coefficient: 287 (12)
H-atom parameters constrained

Special details

Geometry. ENTER SPECIAL DETAILS OF THE MOLECULAR GEOMETRY
Refinement. Refinement using all reflections. The weighted R-factor (wR) and goodness of fit (S) are based on F2. R-factor (gt) are based on F. The threshold expression of F2 > 2.0 σ(F2) is used only for calculating R-factor (gt).

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

xyzUiso*/Ueq
O10.9021 (2)0.3664 (2)0.8067 (2)0.1211 (8)
O20.89199 (16)0.2119 (2)0.40803 (18)0.0749 (6)
N10.8516 (2)0.2377 (2)0.7378 (2)0.0699 (7)
C10.7579 (2)0.2359 (3)0.6043 (2)0.0539 (7)
C20.6914 (2)0.3714 (3)0.5161 (2)0.0519 (7)
C30.6741 (2)0.5115 (3)0.5752 (2)0.0657 (9)
C40.6018 (2)0.6370 (3)0.4891 (3)0.0749 (9)
C50.5479 (2)0.6233 (3)0.3431 (3)0.0794 (10)
C60.5634 (2)0.4858 (3)0.2821 (2)0.0706 (9)
C70.6339 (2)0.3570 (3)0.3658 (2)0.0552 (8)
C80.6389 (2)0.2103 (3)0.2930 (2)0.0569 (8)
C90.5111 (2)0.1408 (3)0.1954 (2)0.0729 (9)
C100.5107 (3)0.0054 (4)0.1245 (2)0.0890 (11)
C110.6400 (3)−0.0637 (3)0.1491 (2)0.0910 (11)
C120.7694 (3)0.0020 (3)0.2437 (2)0.0775 (10)
C130.7690 (2)0.1373 (3)0.3151 (2)0.0644 (9)
C141.0274 (2)0.1362 (3)0.4454 (3)0.0978 (11)
C150.9129 (2)0.0920 (3)0.8265 (2)0.0704 (9)
C160.8509 (3)−0.0534 (3)0.7407 (3)0.1022 (12)
C171.0746 (2)0.0986 (4)0.8838 (3)0.1160 (12)
C180.8694 (2)0.1013 (4)0.9492 (2)0.1048 (11)
H10.73070.13850.56100.065*
H30.71180.52110.67450.079*
H40.59000.72940.53020.090*
H50.50040.70740.28470.095*
H60.52600.47870.18260.085*
H90.42320.18780.17780.087*
H100.4238−0.03900.06050.107*
H110.6405−0.15580.10160.109*
H120.8566−0.04520.25910.093*
H1411.02700.03610.48730.117*
H1421.04250.12220.36080.117*
H1431.10400.19920.51350.117*
H1610.8724−0.05520.65900.123*
H1620.7479−0.05460.70850.123*
H1630.8929−0.14350.79950.123*
H1711.10860.19910.92630.139*
H1721.11730.01870.95500.139*
H1731.10150.08220.80660.139*
H1810.88920.00330.99930.126*
H1820.76780.12400.91170.126*
H1830.92370.18271.01440.126*

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
O10.1395 (18)0.0722 (15)0.0812 (15)−0.0167 (15)−0.0179 (12)−0.0059 (13)
O20.0562 (9)0.0805 (13)0.0934 (13)0.0110 (10)0.0374 (8)−0.0032 (12)
N10.0728 (13)0.0637 (16)0.0555 (14)−0.0094 (14)0.0113 (11)−0.0029 (14)
C10.0509 (11)0.0599 (18)0.0493 (15)−0.0037 (15)0.0203 (11)−0.0017 (15)
C20.0405 (12)0.0608 (18)0.0561 (16)−0.0024 (12)0.0227 (11)−0.0011 (15)
C30.0477 (14)0.078 (2)0.0703 (19)−0.0052 (14)0.0250 (13)−0.0124 (18)
C40.0504 (14)0.068 (2)0.103 (2)0.0064 (15)0.0308 (14)−0.0027 (19)
C50.0627 (16)0.076 (2)0.097 (2)0.0188 (17)0.0328 (16)0.021 (2)
C60.0618 (16)0.082 (2)0.069 (2)0.0091 (15)0.0299 (14)0.0130 (19)
C70.0431 (13)0.0695 (19)0.0572 (17)0.0068 (14)0.0257 (11)0.0083 (17)
C80.0621 (14)0.0682 (19)0.0450 (14)0.0043 (16)0.0274 (12)0.0012 (15)
C90.0699 (17)0.094 (2)0.0497 (16)0.0017 (16)0.0212 (13)−0.0003 (17)
C100.102 (2)0.103 (2)0.0586 (19)−0.015 (2)0.0314 (17)−0.012 (2)
C110.126 (2)0.086 (2)0.067 (2)−0.004 (2)0.0474 (19)−0.0130 (18)
C120.097 (2)0.078 (2)0.069 (2)0.0104 (17)0.0472 (17)0.0009 (18)
C130.0699 (16)0.075 (2)0.0579 (17)0.0022 (16)0.0366 (13)0.0008 (16)
C140.0666 (15)0.105 (2)0.130 (2)0.0198 (18)0.0496 (15)0.008 (2)
C150.0706 (17)0.069 (2)0.0573 (18)0.0000 (17)0.0146 (13)0.0103 (17)
C160.129 (2)0.066 (2)0.087 (2)0.008 (2)0.0230 (19)0.0098 (19)
C170.0771 (17)0.121 (2)0.124 (2)0.003 (2)0.0196 (16)0.033 (2)
C180.113 (2)0.120 (2)0.0668 (19)0.010 (2)0.0254 (17)0.025 (2)

Geometric parameters (Å, °)

O1—N11.291 (3)C1—H10.930
O2—C131.366 (2)C3—H30.930
O2—C141.425 (3)C4—H40.930
N1—C11.293 (2)C5—H50.930
N1—C151.514 (3)C6—H60.930
C1—C21.450 (3)C9—H90.930
C2—C31.391 (4)C10—H100.930
C2—C71.407 (3)C11—H110.930
C3—C41.386 (3)C12—H120.930
C4—C51.368 (4)C14—H1410.960
C5—C61.376 (4)C14—H1420.960
C6—C71.394 (3)C14—H1430.960
C7—C81.476 (3)C16—H1610.960
C8—C91.393 (3)C16—H1620.960
C8—C131.399 (3)C16—H1630.960
C9—C101.370 (4)C17—H1710.960
C10—C111.371 (5)C17—H1720.960
C11—C121.381 (3)C17—H1730.960
C12—C131.373 (4)C18—H1810.960
C15—C161.499 (3)C18—H1820.960
C15—C171.500 (3)C18—H1830.960
C15—C181.518 (4)
C13—O2—C14118.1 (2)C4—C5—H5119.8
O1—N1—C1122.2 (2)C6—C5—H5119.8
O1—N1—C15114.02 (18)C5—C6—H6119.2
C1—N1—C15123.8 (2)C7—C6—H6119.2
N1—C1—C2126.1 (2)C8—C9—H9118.9
C1—C2—C3121.9 (2)C10—C9—H9118.9
C1—C2—C7118.8 (2)C9—C10—H10120.4
C3—C2—C7119.2 (2)C11—C10—H10120.4
C2—C3—C4121.4 (2)C10—C11—H11119.7
C3—C4—C5119.2 (2)C12—C11—H11119.7
C4—C5—C6120.5 (2)C11—C12—H12120.1
C5—C6—C7121.6 (2)C13—C12—H12120.1
C2—C7—C6118.1 (2)O2—C14—H141109.5
C2—C7—C8123.1 (2)O2—C14—H142109.5
C6—C7—C8118.7 (2)O2—C14—H143109.5
C7—C8—C9120.2 (2)H141—C14—H142109.5
C7—C8—C13122.56 (19)H141—C14—H143109.5
C9—C8—C13117.3 (2)H142—C14—H143109.5
C8—C9—C10122.1 (2)C15—C16—H161109.5
C9—C10—C11119.2 (2)C15—C16—H162109.5
C10—C11—C12120.7 (3)C15—C16—H163109.5
C11—C12—C13119.9 (3)H161—C16—H162109.5
O2—C13—C8115.4 (2)H161—C16—H163109.5
O2—C13—C12123.7 (2)H162—C16—H163109.5
C8—C13—C12120.9 (2)C15—C17—H171109.5
N1—C15—C16111.56 (19)C15—C17—H172109.5
N1—C15—C17107.7 (2)C15—C17—H173109.5
N1—C15—C18105.5 (2)H171—C17—H172109.5
C16—C15—C17112.1 (2)H171—C17—H173109.5
C16—C15—C18109.6 (2)H172—C17—H173109.5
C17—C15—C18110.1 (2)C15—C18—H181109.5
N1—C1—H1116.9C15—C18—H182109.5
C2—C1—H1116.9C15—C18—H183109.5
C2—C3—H3119.3H181—C18—H182109.5
C4—C3—H3119.3H181—C18—H183109.5
C3—C4—H4120.4H182—C18—H183109.5
C5—C4—H4120.4
C14—O2—C13—C8174.2 (2)C3—C4—C5—C60.9 (4)
C14—O2—C13—C12−7.4 (4)C4—C5—C6—C7−0.1 (3)
O1—N1—C1—C2−3.3 (4)C5—C6—C7—C2−0.9 (4)
O1—N1—C15—C16−179.7 (2)C5—C6—C7—C8176.3 (2)
O1—N1—C15—C17−56.2 (3)C2—C7—C8—C9121.0 (2)
O1—N1—C15—C1861.4 (2)C2—C7—C8—C13−60.5 (4)
C1—N1—C15—C16−0.3 (4)C6—C7—C8—C9−56.0 (3)
C1—N1—C15—C17123.2 (2)C6—C7—C8—C13122.5 (2)
C1—N1—C15—C18−119.2 (2)C7—C8—C9—C10179.5 (2)
C15—N1—C1—C2177.4 (2)C7—C8—C13—O2−0.6 (4)
N1—C1—C2—C3−26.8 (4)C7—C8—C13—C12−179.0 (2)
N1—C1—C2—C7157.7 (2)C9—C8—C13—O2178.0 (2)
C1—C2—C3—C4−175.7 (2)C9—C8—C13—C12−0.5 (4)
C1—C2—C7—C6176.6 (2)C13—C8—C9—C100.9 (4)
C1—C2—C7—C8−0.5 (3)C8—C9—C10—C11−0.5 (5)
C3—C2—C7—C61.0 (3)C9—C10—C11—C12−0.2 (4)
C3—C2—C7—C8−176.1 (2)C10—C11—C12—C130.6 (5)
C7—C2—C3—C4−0.2 (3)C11—C12—C13—O2−178.5 (2)
C2—C3—C4—C5−0.8 (4)C11—C12—C13—C8−0.2 (4)

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
C3—H3···O10.932.262.806 (3)117
C17—H171···O10.962.412.791 (3)104
C18—H181···O1i0.962.503.280 (3)139

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

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: HK2462).

References

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