4-Methyl-3-(2-phenoxy­acet­yl)-5-phenyl-1,3,4-oxadiazinan-2-one

Zukerman-Schpector, J.; Sousa Madureira, L.; Rodrigues, A.; Vinhato, E.; Olivato, P.R.

doi:10.1107/S1600536809020285

organic compounds

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ISSN: 2056-9890

Volume 65| Part 7| July 2009| Page o1468

doi:10.1107/S1600536809020285

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4-Methyl-3-(2-phenoxyacetyl)-5-phenyl-1,3,4-oxadiazinan-2-one

Julio Zukerman-Schpector,^a ^* Lucas Sousa Madureira,^a Alessandro Rodrigues,^b Elisângela Vinhato ^b and Paulo R. Olivato ^b

^aUniversidade Federal de São Carlos, Laboratório de Cristalografia, Estereodinâmica e, Modelagem Molecular, Departamento de Química, 13565-905 São Carlos, SP, Brazil, and ^bUniversidade de São Paulo, Conformational Analysis and Electronic Interactions, Laboratory, Instituto de Química, São Paulo, SP, Brazil
^*Correspondence e-mail: julio@power.ufscar.br

(Received 26 May 2009; accepted 27 May 2009; online 6 June 2009)

The 1,3,4-oxadiazinane ring in the title compound, C₁₈H₁₈N₂O₄, is in a twisted boat conformation. The two carbonyl groups are orientated towards the same side of the molecule. The dihedral angle between the planes of the benzene rings is 76.6 (3)°. Molecules are sustained in the three-dimensional structure by a combination of C—H⋯O, C—H⋯π and π–π [shortest centroid–centroid distance = 3.672 (6) Å] interactions.

Related literature

For synthetic and structural studies of substituted heterocyclic rings, see: Rodrigues et al. (2006 ). For puckering parameters, see: Cremer & Pople (1975 ); Iulek & Zukerman-Schpector (1997 ). For the synthesis, see: Rodrigues et al. (2005 ).

Experimental

Crystal data

C₁₈H₁₈N₂O₄
M_r = 326.34
Monoclinic, P 2₁ /c
a = 9.6024 (9) Å
b = 9.4203 (10) Å
c = 19.275 (3) Å
β = 114.206 (9)°
V = 1590.3 (4) Å³
Z = 4
Mo Kα radiation
μ = 0.10 mm⁻¹
T = 290 K
0.15 × 0.10 × 0.08 mm

Data collection

Enraf–Nonius CAD-4 diffractometer
Absorption correction: none
2971 measured reflections
2793 independent reflections
1355 reflections with I > 2σ(I)
R_int = 0.030
3 standard reflections frequency: 60 min intensity decay: <1%

Refinement

R[F² > 2σ(F²)] = 0.064
wR(F²) = 0.246
S = 1.12
2793 reflections
218 parameters
H-atom parameters constrained
Δρ_max = 0.19 e Å⁻³
Δρ_min = −0.23 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C7—H7⋯O4ⁱ	0.93	2.53	3.394 (7)	154
C9—H9⋯O3ⁱⁱ	0.93	2.61	3.383 (8)	141
C13—H13⋯Cg2ⁱⁱⁱ	0.93	2.86	3.715 (6)	153
C18—H18B⋯Cg3ⁱ	0.96	2.74	3.672 (6)	165
Symmetry codes: (i) -x+2, -y+1, -z; (ii) $[-x+2, y+{\script{1\over 2}}, -z+{\script{1\over 2}}]$ ; (iii) x+1, y, z. Cg2 is the centroid of the C6–C11 ring and Cg3 is the centroid of the C12–C17 ring.

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: SIR97 (Altomare et al., 1999 ); 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 ), PARST (Nardelli, 1995 ) and MarvinSketch (ChemAxon, 2008 ).

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536809020285/tk2466sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536809020285/tk2466Isup2.hkl

checkCIF report

Comment top

In continuation of synthetic and structural studies of substituted heterocyclic rings (Rodrigues et al., 2006), the title compound (I) was prepared. The 1,3,4-oxadiazinane ring in (I), Fig. 1, is in a distorted twist boat conformation with the distortion being towards a boat conformation. The ring-puckering parameters (Cremer & Pople, 1975; Iulek & Zukerman-Schpector, 1997) were calculated as q₂ = 0.119 (6) Å, q₃ = -0.496 (6) Å, Q = 0.510 (6) Å, and ϕ₂ = -108 (3)°. The ring- and side-chain-bound carbonyl groups lie to the same side of the molecule. The dihedral angle between the phenyl rings is of 76.6 (3)°. Molecules are sustained in the 3-D structure by a combination of C-H···O and π–π interactions, Table 1.

Related literature top

For synthetic and structural studies of substituted heterocyclic

rings, see: Rodrigues et al. (2006). For puckering parameters, see: Cremer & Pople (1975); Iulek & Zukerman-Schpector (1997). For the synthesis, see: Rodrigues et al. (2005). Cg2 is the centroid of the C6–C11 ring and Cg3 is the centroid of the C12–C17 ring.

Experimental top

The starting (R)-4-methyl-5-phenyl-1,3,4-oxadiazinan-2-one was synthesized by using a previously reported procedure (Rodrigues et al. 2005). The phenoxyacetyl-1,3,4-oxadiazinan-2-one derivative was prepared by an acylation reaction of 1,3,4-oxadiazinan-2-one (Rodrigues et al. 2005). To a mixture of 1,3,4-oxadiazinan-2-one (500 mg, 2.60 mmol), 4-dimethylaminopyridine (16 mg, 0.13 mmol) and 2-phenoxyacetic acid (435 mg, 2.86 mmol) in CH₂Cl₂ (4 ml) at 273 K, under a nitrogen atmosphere, N,N-Dicyclohexylcarbodiimide was added in one portion (590 mg, 2.86 mmol). The temperature of the resulting suspension was allowed to reach room temperature. Stirring was continued until no starting material was left, as confirmed by TLC (20 h). The dicyclohexylurea formed was filtered and the precipitate washed with CH₂Cl₂ (20 ml). The filtrate was washed with a saturated aqueous solution of NaHCO₃ (15 ml) and dried over Na₂SO₄. Filtration and evaporation yielded the crude solid, which was purified by flash chromatography on silica gel (hexane-EtOAc, 6:4). Colourless crystals of (I) were obtained by vapour diffusion from hexane/chloroform 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: SIR97 (Altomare et al., 1999); 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), PARST (Nardelli, 1995) and MarvinSketch (ChemAxon, 2008).

Figures top

Fig. 1. The molecular structure of (I) showing atom labelling scheme and displacement ellipsoids at the 50% probability level (arbitrary spheres for the H atoms).

(5R)-4-Methyl-3-(2-phenoxyacetyl)-5-phenyl-1,3,4-oxadiazinan-2-one top

Crystal data top

C₁₈H₁₈N₂O₄	F(000) = 688
M_r = 326.34	D_x = 1.363 Mg m⁻³
Monoclinic, P2₁/c	Melting point = 385–387 K
Hall symbol: -P 2ybc	Mo Kα radiation, λ = 0.71073 Å
a = 9.6024 (9) Å	Cell parameters from 24 reflections
b = 9.4203 (10) Å	θ = 10.5–15.1°
c = 19.275 (3) Å	µ = 0.10 mm⁻¹
β = 114.206 (9)°	T = 290 K
V = 1590.3 (4) Å³	Irregular, colourless
Z = 4	0.15 × 0.10 × 0.08 mm

Data collection top

Enraf–Nonius CAD-4 diffractometer	R_int = 0.030
Radiation source: fine-focus sealed tube	θ_max = 25.0°, θ_min = 2.3°
Graphite monochromator	h = −11→0
ω–2θ scans	k = 0→11
2971 measured reflections	l = −20→20
2793 independent reflections	3 standard reflections every 60 min
1355 reflections with I > 2σ(I)	intensity decay: <1%

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)] = 0.064	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.246	H-atom parameters constrained
S = 1.12	w = 1/[σ²(F_o²) + (0.0852P)² + 2.8996P] where P = (F_o² + 2F_c²)/3
2793 reflections	(Δ/σ)_max < 0.001
218 parameters	Δρ_max = 0.19 e Å⁻³
0 restraints	Δρ_min = −0.23 e Å⁻³

Crystal data top

C₁₈H₁₈N₂O₄	V = 1590.3 (4) Å³
M_r = 326.34	Z = 4
Monoclinic, P2₁/c	Mo Kα radiation
a = 9.6024 (9) Å	µ = 0.10 mm⁻¹
b = 9.4203 (10) Å	T = 290 K
c = 19.275 (3) Å	0.15 × 0.10 × 0.08 mm
β = 114.206 (9)°

Data collection top

Enraf–Nonius CAD-4 diffractometer	R_int = 0.030
2971 measured reflections	3 standard reflections every 60 min
2793 independent reflections	intensity decay: <1%
1355 reflections with I > 2σ(I)

Refinement top

R[F² > 2σ(F²)] = 0.064	0 restraints
wR(F²) = 0.246	H-atom parameters constrained
S = 1.12	Δρ_max = 0.19 e Å⁻³
2793 reflections	Δρ_min = −0.23 e Å⁻³
218 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 > σ(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	0.6770 (6)	0.3140 (6)	−0.0050 (3)	0.0504 (14)
H1	0.6177	0.3840	−0.0433	0.060*
C2	0.5715 (6)	0.1861 (6)	−0.0126 (4)	0.0676 (18)
H2A	0.5123	0.2040	0.0169	0.081*
H2B	0.5008	0.1758	−0.0655	0.081*
C3	0.8059 (6)	0.0406 (6)	0.0376 (3)	0.0530 (14)
C4	1.0422 (5)	0.1778 (6)	0.0667 (3)	0.0411 (12)
C5	1.0994 (5)	0.3123 (6)	0.0478 (3)	0.0492 (13)
H5A	1.0756	0.3145	−0.0062	0.059*
H5B	1.0487	0.3921	0.0593	0.059*
C6	0.7359 (5)	0.3870 (6)	0.0714 (3)	0.0419 (12)
C7	0.7468 (6)	0.5357 (6)	0.0737 (3)	0.0550 (14)
H7	0.7155	0.5862	0.0284	0.066*
C8	0.8025 (8)	0.6080 (7)	0.1415 (4)	0.0690 (18)
H8	0.8055	0.7067	0.1416	0.083*
C9	0.8541 (7)	0.5350 (9)	0.2091 (4)	0.0735 (19)
H9	0.8956	0.5837	0.2551	0.088*
C10	0.8439 (7)	0.3903 (8)	0.2083 (3)	0.0643 (17)
H10	0.8769	0.3407	0.2539	0.077*
C11	0.7850 (6)	0.3167 (7)	0.1400 (3)	0.0596 (16)
H11	0.7784	0.2182	0.1405	0.071*
C12	1.3081 (6)	0.3918 (6)	0.1593 (3)	0.0452 (12)
C13	1.4569 (5)	0.4434 (6)	0.1878 (3)	0.0498 (14)
H13	1.5174	0.4293	0.1612	0.060*
C18	0.7580 (7)	0.2267 (6)	−0.1031 (3)	0.0593 (16)
H18A	0.8470	0.2022	−0.1114	0.089*
H18B	0.7058	0.3041	−0.1358	0.089*
H18C	0.6912	0.1461	−0.1141	0.089*
C14	1.5132 (6)	0.5148 (6)	0.2553 (3)	0.0573 (15)
H14	1.6120	0.5508	0.2739	0.069*
C15	1.4279 (7)	0.5343 (7)	0.2958 (3)	0.0640 (17)
H15	1.4668	0.5849	0.3412	0.077*
C16	1.2833 (7)	0.4782 (7)	0.2689 (3)	0.0650 (16)
H16	1.2256	0.4878	0.2973	0.078*
C17	1.2231 (6)	0.4082 (6)	0.2007 (3)	0.0544 (14)
H17	1.1244	0.3719	0.1826	0.065*
N1	0.8837 (4)	0.1580 (4)	0.0262 (2)	0.0420 (10)
N2	0.8042 (4)	0.2689 (4)	−0.0233 (2)	0.0383 (10)
O1	0.6553 (4)	0.0565 (4)	0.0129 (3)	0.0744 (13)
O2	0.8648 (5)	−0.0680 (4)	0.0671 (3)	0.0712 (12)
O3	1.1208 (4)	0.0946 (4)	0.1131 (2)	0.0611 (11)
O4	1.2593 (4)	0.3245 (4)	0.0898 (2)	0.0569 (11)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
C1	0.041 (3)	0.043 (3)	0.057 (3)	0.004 (2)	0.010 (2)	0.003 (3)
C2	0.041 (3)	0.054 (4)	0.098 (5)	−0.001 (3)	0.019 (3)	0.001 (3)
C3	0.046 (3)	0.046 (3)	0.066 (4)	−0.001 (3)	0.022 (3)	0.003 (3)
C4	0.041 (3)	0.044 (3)	0.035 (3)	0.009 (2)	0.012 (2)	0.000 (2)
C5	0.036 (3)	0.063 (4)	0.044 (3)	−0.001 (3)	0.012 (2)	0.000 (3)
C6	0.037 (3)	0.044 (3)	0.049 (3)	0.005 (2)	0.022 (2)	0.004 (3)
C7	0.062 (4)	0.051 (3)	0.057 (3)	0.001 (3)	0.029 (3)	0.003 (3)
C8	0.089 (5)	0.056 (4)	0.073 (4)	−0.013 (4)	0.045 (4)	−0.018 (4)
C9	0.066 (4)	0.100 (6)	0.063 (4)	−0.003 (4)	0.035 (3)	−0.020 (4)
C10	0.067 (4)	0.082 (5)	0.053 (4)	0.019 (4)	0.034 (3)	0.014 (4)
C11	0.058 (4)	0.058 (4)	0.070 (4)	0.005 (3)	0.034 (3)	0.011 (3)
C12	0.040 (3)	0.046 (3)	0.047 (3)	0.005 (2)	0.016 (2)	0.001 (3)
C13	0.034 (3)	0.057 (3)	0.054 (3)	0.003 (3)	0.014 (2)	0.004 (3)
C18	0.059 (3)	0.057 (4)	0.046 (3)	0.007 (3)	0.005 (3)	−0.004 (3)
C14	0.039 (3)	0.062 (4)	0.058 (3)	−0.003 (3)	0.007 (3)	0.005 (3)
C15	0.063 (4)	0.066 (4)	0.053 (3)	0.002 (3)	0.014 (3)	−0.016 (3)
C16	0.068 (4)	0.066 (4)	0.068 (4)	−0.001 (3)	0.035 (3)	−0.015 (3)
C17	0.046 (3)	0.053 (3)	0.065 (4)	−0.013 (3)	0.024 (3)	−0.016 (3)
N1	0.038 (2)	0.038 (2)	0.048 (2)	0.0001 (19)	0.0159 (19)	0.006 (2)
N2	0.036 (2)	0.041 (2)	0.035 (2)	0.0063 (18)	0.0121 (17)	0.0054 (18)
O1	0.047 (2)	0.046 (2)	0.125 (4)	−0.0046 (19)	0.030 (2)	0.012 (2)
O2	0.078 (3)	0.040 (2)	0.099 (3)	0.008 (2)	0.040 (2)	0.024 (2)
O3	0.054 (2)	0.056 (2)	0.058 (2)	0.009 (2)	0.0075 (18)	0.009 (2)
O4	0.0379 (19)	0.080 (3)	0.050 (2)	−0.0048 (19)	0.0159 (16)	−0.015 (2)

Geometric parameters (Å, º) top

C1—N2	1.466 (6)	C9—C10	1.366 (9)
C1—C6	1.511 (7)	C9—H9	0.9300
C1—C2	1.542 (8)	C10—C11	1.386 (8)
C1—H1	0.9800	C10—H10	0.9300
C2—O1	1.433 (7)	C11—H11	0.9300
C2—H2A	0.9700	C12—C17	1.365 (7)
C2—H2B	0.9700	C12—O4	1.378 (6)
C3—O2	1.194 (6)	C12—C13	1.391 (7)
C3—O1	1.332 (6)	C13—C14	1.364 (8)
C3—N1	1.402 (7)	C13—H13	0.9300
C4—O3	1.195 (6)	C18—N2	1.469 (6)
C4—N1	1.410 (6)	C18—H18A	0.9600
C4—C5	1.484 (7)	C18—H18B	0.9600
C5—O4	1.417 (6)	C18—H18C	0.9600
C5—H5A	0.9700	C14—C15	1.355 (9)
C5—H5B	0.9700	C14—H14	0.9300
C6—C11	1.378 (7)	C15—C16	1.373 (8)
C6—C7	1.404 (8)	C15—H15	0.9300
C7—C8	1.372 (8)	C16—C17	1.369 (7)
C7—H7	0.9300	C16—H16	0.9300
C8—C9	1.374 (9)	C17—H17	0.9300
C8—H8	0.9300	N1—N2	1.410 (5)

N2—C1—C6	110.6 (4)	C9—C10—H10	119.7
N2—C1—C2	109.3 (4)	C11—C10—H10	119.7
C6—C1—C2	114.7 (5)	C6—C11—C10	121.1 (6)
N2—C1—H1	107.3	C6—C11—H11	119.5
C6—C1—H1	107.3	C10—C11—H11	119.5
C2—C1—H1	107.3	C17—C12—O4	125.0 (5)
O1—C2—C1	112.2 (4)	C17—C12—C13	119.5 (5)
O1—C2—H2A	109.2	O4—C12—C13	115.5 (5)
C1—C2—H2A	109.2	C14—C13—C12	119.4 (5)
O1—C2—H2B	109.2	C14—C13—H13	120.3
C1—C2—H2B	109.2	C12—C13—H13	120.3
H2A—C2—H2B	107.9	N2—C18—H18A	109.5
O2—C3—O1	119.9 (5)	N2—C18—H18B	109.5
O2—C3—N1	124.9 (5)	H18A—C18—H18B	109.5
O1—C3—N1	115.2 (5)	N2—C18—H18C	109.5
O3—C4—N1	122.3 (5)	H18A—C18—H18C	109.5
O3—C4—C5	124.0 (5)	H18B—C18—H18C	109.5
N1—C4—C5	113.6 (4)	C15—C14—C13	121.3 (5)
O4—C5—C4	110.6 (4)	C15—C14—H14	119.4
O4—C5—H5A	109.5	C13—C14—H14	119.4
C4—C5—H5A	109.5	C14—C15—C16	119.1 (5)
O4—C5—H5B	109.5	C14—C15—H15	120.5
C4—C5—H5B	109.5	C16—C15—H15	120.5
H5A—C5—H5B	108.1	C17—C16—C15	120.8 (6)
C11—C6—C7	117.3 (5)	C17—C16—H16	119.6
C11—C6—C1	124.1 (5)	C15—C16—H16	119.6
C7—C6—C1	118.6 (5)	C12—C17—C16	119.8 (5)
C8—C7—C6	121.4 (6)	C12—C17—H17	120.1
C8—C7—H7	119.3	C16—C17—H17	120.1
C6—C7—H7	119.3	C3—N1—N2	121.0 (4)
C7—C8—C9	120.2 (6)	C3—N1—C4	122.8 (4)
C7—C8—H8	119.9	N2—N1—C4	116.0 (4)
C9—C8—H8	119.9	N1—N2—C1	109.0 (4)
C10—C9—C8	119.5 (6)	N1—N2—C18	110.8 (4)
C10—C9—H9	120.3	C1—N2—C18	114.0 (4)
C8—C9—H9	120.3	C3—O1—C2	126.3 (4)
C9—C10—C11	120.6 (6)	C12—O4—C5	116.7 (4)

N2—C1—C2—O1	37.4 (7)	C15—C16—C17—C12	1.0 (10)
C6—C1—C2—O1	−87.4 (6)	O2—C3—N1—N2	165.9 (5)
O3—C4—C5—O4	2.4 (7)	O1—C3—N1—N2	−14.2 (7)
N1—C4—C5—O4	−179.3 (4)	O2—C3—N1—C4	−18.8 (9)
N2—C1—C6—C11	−82.9 (6)	O1—C3—N1—C4	161.1 (5)
C2—C1—C6—C11	41.2 (7)	O3—C4—N1—C3	0.8 (8)
N2—C1—C6—C7	94.9 (6)	C5—C4—N1—C3	−177.6 (5)
C2—C1—C6—C7	−141.0 (5)	O3—C4—N1—N2	176.3 (4)
C11—C6—C7—C8	−0.6 (8)	C5—C4—N1—N2	−2.0 (6)
C1—C6—C7—C8	−178.5 (5)	C3—N1—N2—C1	49.4 (6)
C6—C7—C8—C9	2.2 (9)	C4—N1—N2—C1	−126.2 (4)
C7—C8—C9—C10	−2.5 (10)	C3—N1—N2—C18	−76.8 (6)
C8—C9—C10—C11	1.2 (10)	C4—N1—N2—C18	107.6 (5)
C7—C6—C11—C10	−0.6 (8)	C6—C1—N2—N1	68.9 (5)
C1—C6—C11—C10	177.1 (5)	C2—C1—N2—N1	−58.2 (5)
C9—C10—C11—C6	0.3 (9)	C6—C1—N2—C18	−166.8 (4)
C17—C12—C13—C14	−2.7 (8)	C2—C1—N2—C18	66.1 (6)
O4—C12—C13—C14	178.3 (5)	O2—C3—O1—C2	169.7 (6)
C12—C13—C14—C15	1.2 (9)	N1—C3—O1—C2	−10.2 (9)
C13—C14—C15—C16	1.4 (9)	C1—C2—O1—C3	−3.0 (9)
C14—C15—C16—C17	−2.5 (10)	C17—C12—O4—C5	21.0 (8)
O4—C12—C17—C16	−179.5 (5)	C13—C12—O4—C5	−160.0 (5)
C13—C12—C17—C16	1.6 (9)	C4—C5—O4—C12	−90.5 (6)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C7—H7···O4ⁱ	0.93	2.53	3.394 (7)	154
C9—H9···O3ⁱⁱ	0.93	2.61	3.383 (8)	141
C13—H13···Cg2ⁱⁱⁱ	0.93	2.86	3.715 (6)	153
C18—H18B···Cg3ⁱ	0.96	2.74	3.672 (6)	165

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

Experimental details

Crystal data
Chemical formula	C₁₈H₁₈N₂O₄
M_r	326.34
Crystal system, space group	Monoclinic, P2₁/c
Temperature (K)	290
a, b, c (Å)	9.6024 (9), 9.4203 (10), 19.275 (3)
β (°)	114.206 (9)
V (Å³)	1590.3 (4)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.10
Crystal size (mm)	0.15 × 0.10 × 0.08

Data collection
Diffractometer	Enraf–Nonius CAD-4 diffractometer
Absorption correction	–
No. of measured, independent and observed [I > 2σ(I)] reflections	2971, 2793, 1355
R_int	0.030
(sin θ/λ)_max (Å⁻¹)	0.595

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.064, 0.246, 1.12
No. of reflections	2793
No. of parameters	218
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.19, −0.23

Computer programs: CAD-4 EXPRESS (Enraf–Nonius, 1994), XCAD4 (Harms & Wocadlo, 1995), SIR97 (Altomare et al., 1999), SHELXL97 (Sheldrick, 2008), ORTEP-3 for Windows (Farrugia, 1997), WinGX (Farrugia, 1999), PARST (Nardelli, 1995) and MarvinSketch (ChemAxon, 2008).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C7—H7···O4ⁱ	0.93	2.53	3.394 (7)	154
C9—H9···O3ⁱⁱ	0.93	2.61	3.383 (8)	141
C13—H13···Cg2ⁱⁱⁱ	0.93	2.86	3.715 (6)	153
C18—H18B···Cg3ⁱ	0.96	2.74	3.672 (6)	165

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

Acknowledgements

We thank FAPESP (2008/02531–5 to JZ—S; 2003/05520–0 to AR), CNPq and CAPES for financial support.

References

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