Absolute configuration of odorine

Fun, H.-K.; Chantrapromma, S.; Yodsaoue, O.; Karalai, C.

doi:10.1107/S1600536810034227

organic compounds

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ISSN: 2056-9890

Volume 66| Part 9| September 2010| Pages o2437-o2438

https://doi.org/10.1107/S1600536810034227

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Absolute configuration of odorine

Hoong-Kun Fun,^a ^*‡ Suchada Chantrapromma,^b § Orapun Yodsaoue ^c and Chatchanok Karalai ^c

^aX-ray Crystallography Unit, School of Physics, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia, ^bCrystal Materials Research Unit, Department of Chemistry, Faculty of Science, Prince of Songkla University, Hat-Yai, Songkhla 90112, Thailand, and ^cDepartment of Chemistry, Faculty of Science, Prince of Songkla University, Hat-Yai, Songkhla 90112, Thailand
^*Correspondence e-mail: hkfun@usm.my

(Received 16 August 2010; accepted 25 August 2010; online 28 August 2010)

The title compound, known as odorine or roxburghiline {systematic name: (S)-N-[(R)-1-cinnamoylpyrrolidin-2-yl]-2-methylbutanamide}, C₁₈H₂₄N₂O₂, is a nitrogenous compound isolated from the leaves of Aglaia odorata. The absolute configuration was determined by refinement of the Flack parameter with data collected using Cu Kα radiation showing positions 2 and 2′ to be S and R, respectively. The pyrrolidine ring adopts an envelope conformation. In the crystal, molecules are linked into chains along [010] by intermolecular N—H⋯O hydrogen bonds.

Related literature

For ring conformations, see: Cremer & Pople (1975 ). For standard bond-length data, see: Allen et al. (1987 ). For background to the Aglaia plants and their biological activity, see: Brader et al. (1998 ); Cui et al. (1997 ); Engelmeier et al. (2000 ); Hayashi et al. (1982 ); Inada et al. (2001 ); Nugroho et al. (1999 ); Purushothaman et al. 1979 ); Saifah et al. (1993 ); Shiengthong et al. (1979 ). For related structures, see: Babidge et al. (1980 ); Dumontet et al. (1996 ); Hayashi et al. (1982). For the stability of the temperature controller used in the data collection, see Cosier & Glazer (1986 ).

Experimental

Crystal data

C₁₈H₂₄N₂O₂
M_r = 300.39
Monoclinic, C 2
a = 18.8909 (3) Å
b = 6.8398 (1) Å
c = 13.4174 (2) Å
β = 107.054 (1)°
V = 1657.43 (4) Å³
Z = 4
Cu Kα radiation
μ = 0.63 mm⁻¹
T = 100 K
0.57 × 0.16 × 0.13 mm

Data collection

Bruker APEXII DUO CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2009 ) T_min = 0.718, T_max = 0.924
10656 measured reflections
2625 independent reflections
2606 reflections with I > 2σ(I)
R_int = 0.042

Refinement

R[F² > 2σ(F²)] = 0.033
wR(F²) = 0.096
S = 1.16
2625 reflections
205 parameters
1 restraint
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.21 e Å⁻³
Δρ_min = −0.27 e Å⁻³
Absolute structure: Flack (1983 ), 1036 Friedel pairs
Flack parameter: 0.03 (18)

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N2—H1N2⋯O1ⁱ	0.81 (2)	2.09 (2)	2.8789 (16)	163 (2)
Symmetry code: (i) $[-x+{\script{3\over 2}}, y-{\script{1\over 2}}, -z+1]$ .

Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2009 ).

Supporting information

Crystal structure: contains datablocks global, I. DOI: https://doi.org/10.1107/S1600536810034227/lh5122sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536810034227/lh5122Isup2.hkl

checkCIF report

Comment top

Several species of the genus Aglaia of the family Meliaceae are of ethnomedicinal values and have insecticidal (Brader et al., 1998), antifungal (Engelmeier et al., 2000) and cytotoxic (Saifah et al., 1993; Cui et al., 1997) activities. These interesting activities have prompted us to screen for further bioactive compounds from Aglaia odorata. Aglaia odorata known locally in Thai as "Pra-yong" or "Hom-glai" is a small tree occurring primarily in South-East Asia. The leaves and roots of this plant have been used in local folk medicine as a heart stimulant, febrifuge and to retrieve toxin by causing vomiting. The isolated compounds from this plant also show interesting biological activities such as anticancer (Inada et al., 2001), insecticidal (Nugroho et al., 1999) and anti-leukemic (Hayashi et al., 1982) activities. In the course of our research of chemical constituents and bioactive compounds from the leaves of A. odorata which were collected from Songkhla province in the southern part of Thailand, the title aminopyrrolidine odorine (I), also known as odorine (Shiengthong et al., 1979) or roxburghiline or N-cinnamoyl-2-(2-methylbutanoylamino)pyrrolidine (Purushothaman et al., 1979) was isolated. The previous report showed that (I) possesses cancer-chemopreventive activity (Inada et al., 2001). The absolute configuration of (I) was determined by making use of the anomalous scattering of Cu Kα X-radiation with the Flack parameter being refined to 0.03 (18). We report herein the crystal structure of (I).

Fig. 1 shows that the molecule of (I) possesses a 2-aminopyrrolidine ring linked by two amide functions to 2-methylbutyric acid and cinnamic acid. The pyrrolidine ring adopts an envelope conformation with the puckered C12 atom having a deviation of 0.223 (1) Å and with the puckering parameters Q = 0.3522 (15) Å and θ = 281.3 (2)° (Cremer & Pople, 1975). Atoms of the cinnamoyl (C1–C9/O1) moiety essentially lie on the same plane (r.m.s. 0.0216 (1) Å) with a max. deviation of 0.0583 (1) Å for atom O1. Atoms C13, C14, C15, N2 and O2 lie on the same plane (r.m.s. 0.0216 (1) Å). The mean plane through C13/C14/C15/N2/O2 makes the dihedral angle of 88.80 (7)° with the mean plane through the cinnamoyl moiety. The 2-methylbutanamide chain at C13 is pseudo-axial with the C14–N2–C13–C12 torsion angle = 125.55 (13)°. The orientation of the butyl group is described by the torsion angle C14–C15–C17–C18 = 68.78 (18)°. The bond distances in (I) are within normal ranges (Allen et al., 1987) and comparable with the related structures which are odorinol (Hayashi et al., 1982) and forbaglin A (Dumontet et al., 1996). The absolute configuration at atoms C15 and C13 or positions 2 and 2' of the odorine are S,R configurations which agree with the previous stereochemistry of odorine (Babidge et al., 1980).

In the crystal packing of (I) (Fig. 2), the molecules are linked into chains along [010] through N2—H1N2···O1ⁱ hydrogen bonds (Fig. 2 and Table 1).

Related literature top

For ring conformations, see: Cremer & Pople (1975). For standard bond-length data, see: Allen et al. (1987). For background to the Aglaia plants and their biological activity, see: Brader et al. (1998); Cui et al. (1997); Engelmeier et al. (2000); Hayashi et al. (1982); Inada et al. (2001); Nugroho et al. (1999); Purushothaman et al. 1979); Saifah et al. (1993); Shiengthong et al. (1979). For related structures, see: Babidge et al. (1980); Dumontet et al. (1996); Hayashi et al. (1982). For the stability of the temperature controller used in the data collection, see Cosier & Glazer (1986).

Experimental top

Ground-dried leaves of A. odorata (53.70 g) were extracted with CH₂Cl₂ and CH₃OH (each of 2 x 2 L) for a duration of 3 days at room temperature. The solvents were evaporated under reduced pressure to afford CH₂Cl₂ (23.50 g) and CH₃OH (5.23 g) crude extracts, respectively. The CH₂Cl₂ crude extract (23.50 g) was further purified by quick column chromatography (QCC) over silica gel using hexane as eluent and increasing polarity with EtOAc and CH₃OH to afford 10 fractions (F1-F10). Fraction F10 (231.6 mg) was further separated by column chromatography with acetone-hexane (3:7), yielding the title compound as white solid (15.6 mg). Colorless needle-shaped single crystals of the title compound suitable for x-ray structure determination were recrystallized from CH₂Cl₂ by the slow evaporation of the solvent at room temperature after several days, Mp. 476-478 K.

Structure description top

In the crystal packing of (I) (Fig. 2), the molecules are linked into chains along [010] through N2—H1N2···O1ⁱ hydrogen bonds (Fig. 2 and Table 1).

For ring conformations, see: Cremer & Pople (1975). For standard bond-length data, see: Allen et al. (1987). For background to the Aglaia plants and their biological activity, see: Brader et al. (1998); Cui et al. (1997); Engelmeier et al. (2000); Hayashi et al. (1982); Inada et al. (2001); Nugroho et al. (1999); Purushothaman et al. 1979); Saifah et al. (1993); Shiengthong et al. (1979). For related structures, see: Babidge et al. (1980); Dumontet et al. (1996); Hayashi et al. (1982). For the stability of the temperature controller used in the data collection, see Cosier & Glazer (1986).

Computing details top

Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT (Bruker, 2009); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2009).

Figures top

	Fig. 1. The molecular structure of (I), showing 50% probability displacement ellipsoids and the atom-numbering scheme.
	Fig. 2. The crystal packing of (I) viewed approximately along the c axis, showing one dimensional chains along [0 1 0]. N—H···O hydrogen bonds are shown as dashed lines.

(S)-N-[(R)-1-cinnamoylpyrrolidin-2-yl]-2-methylbutanamide top

Crystal data top

C₁₈H₂₄N₂O₂	F(000) = 648
M_r = 300.39	D_x = 1.204 Mg m⁻³
Monoclinic, C2	Melting point = 476–478 K
Hall symbol: C 2y	Cu Kα radiation, λ = 1.54178 Å
a = 18.8909 (3) Å	Cell parameters from 2625 reflections
b = 6.8398 (1) Å	θ = 6.8–67.4°
c = 13.4174 (2) Å	µ = 0.63 mm⁻¹
β = 107.054 (1)°	T = 100 K
V = 1657.43 (4) Å³	Needle, colorless
Z = 4	0.57 × 0.16 × 0.13 mm

Data collection top

Bruker APEXII DUO CCD area-detector diffractometer	2625 independent reflections
Radiation source: sealed tube	2606 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.042
φ and ω scans	θ_max = 67.4°, θ_min = 6.8°
Absorption correction: multi-scan (SADABS; Bruker, 2009)	h = −22→22
T_min = 0.718, T_max = 0.924	k = −7→6
10656 measured reflections	l = −16→16

Refinement top

Refinement on F²	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F² > 2σ(F²)] = 0.033	H atoms treated by a mixture of independent and constrained refinement
wR(F²) = 0.096	w = 1/[σ²(F_o²) + (0.0595P)² + 0.2381P] where P = (F_o² + 2F_c²)/3
S = 1.16	(Δ/σ)_max = 0.001
2625 reflections	Δρ_max = 0.21 e Å⁻³
205 parameters	Δρ_min = −0.27 e Å⁻³
1 restraint	Absolute structure: Flack (1983), 1036 Friedel pairs
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: 0.03 (18)

Crystal data top

C₁₈H₂₄N₂O₂	V = 1657.43 (4) Å³
M_r = 300.39	Z = 4
Monoclinic, C2	Cu Kα radiation
a = 18.8909 (3) Å	µ = 0.63 mm⁻¹
b = 6.8398 (1) Å	T = 100 K
c = 13.4174 (2) Å	0.57 × 0.16 × 0.13 mm
β = 107.054 (1)°

Data collection top

Bruker APEXII DUO CCD area-detector diffractometer	2625 independent reflections
Absorption correction: multi-scan (SADABS; Bruker, 2009)	2606 reflections with I > 2σ(I)
T_min = 0.718, T_max = 0.924	R_int = 0.042
10656 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.033	H atoms treated by a mixture of independent and constrained refinement
wR(F²) = 0.096	Δρ_max = 0.21 e Å⁻³
S = 1.16	Δρ_min = −0.27 e Å⁻³
2625 reflections	Absolute structure: Flack (1983), 1036 Friedel pairs
205 parameters	Absolute structure parameter: 0.03 (18)
1 restraint

Special details top

Experimental. The crystal was placed in the cold stream of an Oxford Cryosystems Cobra open-flow nitrogen cryostat (Cosier & Glazer, 1986) operating at 100.0 (1) K.

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 > 2sigma(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
O1	0.68617 (5)	0.99471 (16)	0.55658 (7)	0.0243 (2)
O2	0.97777 (6)	0.88734 (17)	0.73395 (8)	0.0315 (3)
N1	0.79446 (6)	0.99195 (19)	0.51776 (8)	0.0218 (2)
H1N2	0.8859 (10)	0.691 (3)	0.5433 (14)	0.030 (5)*
N2	0.90244 (6)	0.78710 (19)	0.57796 (9)	0.0217 (3)
C1	0.87323 (8)	0.9894 (3)	0.92951 (11)	0.0299 (3)
H1A	0.9038	1.0059	0.8870	0.036*
C2	0.90374 (8)	0.9818 (3)	1.03621 (11)	0.0348 (4)
H2A	0.9548	0.9923	1.0651	0.042*
C3	0.85882 (8)	0.9585 (3)	1.10083 (11)	0.0325 (4)
H3A	0.8797	0.9538	1.1728	0.039*
C4	0.78306 (9)	0.9425 (3)	1.05783 (11)	0.0337 (4)
H4A	0.7528	0.9273	1.1008	0.040*
C5	0.75221 (8)	0.9490 (2)	0.95025 (11)	0.0285 (3)
H5A	0.7012	0.9376	0.9217	0.034*
C6	0.79653 (7)	0.9725 (2)	0.88465 (10)	0.0233 (3)
C7	0.76210 (7)	0.9768 (2)	0.77145 (10)	0.0236 (3)
H7A	0.7107	0.9679	0.7481	0.028*
C8	0.79691 (7)	0.9920 (2)	0.69898 (9)	0.0219 (3)
H8A	0.8483	1.0019	0.7190	0.026*
C9	0.75502 (7)	0.9936 (2)	0.58677 (9)	0.0207 (3)
C10	0.75678 (7)	0.9890 (2)	0.40514 (9)	0.0233 (3)
H10A	0.7308	1.1109	0.3826	0.028*
H10B	0.7217	0.8819	0.3871	0.028*
C11	0.81922 (8)	0.9613 (2)	0.35579 (10)	0.0275 (3)
H11A	0.8097	1.0348	0.2914	0.033*
H11B	0.8253	0.8243	0.3414	0.033*
C12	0.88773 (8)	1.0396 (2)	0.43814 (11)	0.0276 (3)
H12A	0.9325	0.9808	0.4303	0.033*
H12B	0.8912	1.1805	0.4329	0.033*
C13	0.87590 (7)	0.9813 (2)	0.54206 (10)	0.0222 (3)
H13A	0.8990	1.0781	0.5956	0.027*
C14	0.95055 (7)	0.7544 (2)	0.67329 (11)	0.0237 (3)
C15	0.97075 (8)	0.5412 (2)	0.69919 (11)	0.0293 (3)
H15A	0.9332	0.4576	0.6527	0.035*
C16	1.04558 (10)	0.5039 (3)	0.67983 (16)	0.0512 (5)
H16A	1.0413	0.5272	0.6077	0.077*
H16B	1.0603	0.3708	0.6971	0.077*
H16C	1.0821	0.5903	0.7225	0.077*
C17	0.97552 (9)	0.4934 (3)	0.81232 (12)	0.0356 (4)
H17A	0.9971	0.3644	0.8290	0.043*
H17B	1.0085	0.5865	0.8576	0.043*
C18	0.90143 (10)	0.4977 (3)	0.83531 (12)	0.0406 (4)
H18A	0.9089	0.4729	0.9081	0.061*
H18B	0.8696	0.3990	0.7948	0.061*
H18C	0.8790	0.6238	0.8176	0.061*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1	0.0229 (5)	0.0260 (6)	0.0230 (4)	0.0040 (4)	0.0051 (3)	0.0031 (4)
O2	0.0301 (5)	0.0298 (6)	0.0277 (5)	−0.0005 (4)	−0.0025 (4)	−0.0062 (5)
N1	0.0222 (5)	0.0231 (6)	0.0193 (5)	0.0013 (5)	0.0045 (4)	0.0013 (5)
N2	0.0225 (5)	0.0209 (7)	0.0202 (6)	−0.0006 (5)	0.0039 (4)	−0.0046 (5)
C1	0.0277 (7)	0.0399 (9)	0.0226 (6)	0.0012 (7)	0.0080 (5)	0.0015 (7)
C2	0.0269 (7)	0.0507 (10)	0.0245 (7)	0.0036 (7)	0.0038 (5)	−0.0006 (8)
C3	0.0384 (8)	0.0390 (10)	0.0180 (6)	0.0045 (7)	0.0050 (5)	0.0014 (6)
C4	0.0379 (8)	0.0409 (11)	0.0253 (7)	0.0019 (7)	0.0137 (6)	0.0029 (6)
C5	0.0263 (7)	0.0324 (9)	0.0264 (7)	0.0017 (6)	0.0074 (5)	0.0016 (6)
C6	0.0268 (6)	0.0209 (8)	0.0217 (6)	0.0049 (6)	0.0063 (5)	0.0022 (6)
C7	0.0234 (6)	0.0214 (7)	0.0246 (7)	0.0038 (6)	0.0048 (5)	0.0019 (6)
C8	0.0228 (6)	0.0194 (7)	0.0215 (6)	0.0031 (6)	0.0032 (5)	0.0014 (6)
C9	0.0239 (6)	0.0153 (7)	0.0221 (6)	0.0031 (6)	0.0053 (5)	0.0014 (6)
C10	0.0275 (6)	0.0218 (7)	0.0187 (6)	0.0032 (6)	0.0037 (5)	0.0011 (6)
C11	0.0354 (7)	0.0280 (8)	0.0201 (6)	0.0028 (6)	0.0098 (5)	0.0017 (6)
C12	0.0304 (7)	0.0277 (8)	0.0276 (7)	−0.0002 (6)	0.0132 (5)	0.0028 (6)
C13	0.0219 (6)	0.0214 (7)	0.0234 (6)	−0.0015 (5)	0.0070 (5)	−0.0018 (6)
C14	0.0174 (6)	0.0291 (9)	0.0244 (7)	0.0013 (5)	0.0058 (5)	−0.0013 (6)
C15	0.0278 (7)	0.0293 (9)	0.0290 (7)	0.0059 (6)	0.0058 (6)	−0.0003 (6)
C16	0.0451 (9)	0.0479 (13)	0.0675 (12)	0.0202 (9)	0.0274 (9)	0.0085 (10)
C17	0.0397 (8)	0.0319 (9)	0.0304 (7)	0.0055 (7)	0.0027 (6)	0.0066 (7)
C18	0.0535 (9)	0.0358 (10)	0.0347 (8)	0.0013 (8)	0.0163 (7)	0.0039 (8)

Geometric parameters (Å, º) top

O1—C9	1.2437 (16)	C10—C11	1.5243 (18)
O2—C14	1.2280 (19)	C10—H10A	0.9700
N1—C9	1.3480 (17)	C10—H10B	0.9700
N1—C10	1.4695 (15)	C11—C12	1.531 (2)
N1—C13	1.4780 (16)	C11—H11A	0.9700
N2—C14	1.3529 (17)	C11—H11B	0.9700
N2—C13	1.451 (2)	C12—C13	1.5284 (18)
N2—H1N2	0.81 (2)	C12—H12A	0.9700
C1—C2	1.3787 (19)	C12—H12B	0.9700
C1—C6	1.401 (2)	C13—H13A	0.9800
C1—H1A	0.9300	C14—C15	1.522 (2)
C2—C3	1.389 (2)	C15—C17	1.529 (2)
C2—H2A	0.9300	C15—C16	1.532 (2)
C3—C4	1.382 (2)	C15—H15A	0.9800
C3—H3A	0.9300	C16—H16A	0.9600
C4—C5	1.3898 (19)	C16—H16B	0.9600
C4—H4A	0.9300	C16—H16C	0.9600
C5—C6	1.3907 (19)	C17—C18	1.519 (2)
C5—H5A	0.9300	C17—H17A	0.9700
C6—C7	1.4667 (17)	C17—H17B	0.9700
C7—C8	1.3282 (18)	C18—H18A	0.9600
C7—H7A	0.9300	C18—H18B	0.9600
C8—C9	1.4813 (17)	C18—H18C	0.9600
C8—H8A	0.9300

C9—N1—C10	120.52 (10)	C10—C11—H11B	111.0
C9—N1—C13	126.73 (10)	C12—C11—H11B	111.0
C10—N1—C13	112.65 (10)	H11A—C11—H11B	109.0
C14—N2—C13	122.40 (12)	C13—C12—C11	104.37 (11)
C14—N2—H1N2	116.5 (13)	C13—C12—H12A	110.9
C13—N2—H1N2	120.9 (13)	C11—C12—H12A	110.9
C2—C1—C6	120.50 (13)	C13—C12—H12B	110.9
C2—C1—H1A	119.7	C11—C12—H12B	110.9
C6—C1—H1A	119.7	H12A—C12—H12B	108.9
C1—C2—C3	120.45 (13)	N2—C13—N1	110.75 (11)
C1—C2—H2A	119.8	N2—C13—C12	114.38 (12)
C3—C2—H2A	119.8	N1—C13—C12	101.95 (10)
C4—C3—C2	119.75 (13)	N2—C13—H13A	109.8
C4—C3—H3A	120.1	N1—C13—H13A	109.8
C2—C3—H3A	120.1	C12—C13—H13A	109.8
C3—C4—C5	119.91 (14)	O2—C14—N2	122.61 (14)
C3—C4—H4A	120.0	O2—C14—C15	122.00 (12)
C5—C4—H4A	120.0	N2—C14—C15	115.36 (12)
C4—C5—C6	120.94 (13)	C14—C15—C17	111.68 (13)
C4—C5—H5A	119.5	C14—C15—C16	107.63 (14)
C6—C5—H5A	119.5	C17—C15—C16	110.13 (13)
C5—C6—C1	118.44 (12)	C14—C15—H15A	109.1
C5—C6—C7	119.43 (12)	C17—C15—H15A	109.1
C1—C6—C7	122.13 (12)	C16—C15—H15A	109.1
C8—C7—C6	126.53 (12)	C15—C16—H16A	109.5
C8—C7—H7A	116.7	C15—C16—H16B	109.5
C6—C7—H7A	116.7	H16A—C16—H16B	109.5
C7—C8—C9	120.87 (11)	C15—C16—H16C	109.5
C7—C8—H8A	119.6	H16A—C16—H16C	109.5
C9—C8—H8A	119.6	H16B—C16—H16C	109.5
O1—C9—N1	120.81 (11)	C18—C17—C15	114.07 (12)
O1—C9—C8	121.80 (11)	C18—C17—H17A	108.7
N1—C9—C8	117.39 (11)	C15—C17—H17A	108.7
N1—C10—C11	104.19 (10)	C18—C17—H17B	108.7
N1—C10—H10A	110.9	C15—C17—H17B	108.7
C11—C10—H10A	110.9	H17A—C17—H17B	107.6
N1—C10—H10B	110.9	C17—C18—H18A	109.5
C11—C10—H10B	110.9	C17—C18—H18B	109.5
H10A—C10—H10B	108.9	H18A—C18—H18B	109.5
C10—C11—C12	103.95 (11)	C17—C18—H18C	109.5
C10—C11—H11A	111.0	H18A—C18—H18C	109.5
C12—C11—H11A	111.0	H18B—C18—H18C	109.5

C6—C1—C2—C3	−0.4 (3)	N1—C10—C11—C12	−24.24 (15)
C1—C2—C3—C4	0.2 (3)	C10—C11—C12—C13	35.81 (15)
C2—C3—C4—C5	0.2 (3)	C14—N2—C13—N1	−119.95 (13)
C3—C4—C5—C6	−0.3 (3)	C14—N2—C13—C12	125.55 (13)
C4—C5—C6—C1	0.0 (2)	C9—N1—C13—N2	72.51 (17)
C4—C5—C6—C7	179.40 (15)	C10—N1—C13—N2	−103.96 (13)
C2—C1—C6—C5	0.4 (3)	C9—N1—C13—C12	−165.39 (14)
C2—C1—C6—C7	−179.02 (17)	C10—N1—C13—C12	18.14 (16)
C5—C6—C7—C8	−177.81 (15)	C11—C12—C13—N2	86.96 (14)
C1—C6—C7—C8	1.6 (3)	C11—C12—C13—N1	−32.61 (14)
C6—C7—C8—C9	179.71 (14)	C13—N2—C14—O2	−3.6 (2)
C10—N1—C9—O1	−0.7 (2)	C13—N2—C14—C15	178.31 (11)
C13—N1—C9—O1	−176.95 (14)	O2—C14—C15—C17	41.89 (18)
C10—N1—C9—C8	178.64 (13)	N2—C14—C15—C17	−139.99 (13)
C13—N1—C9—C8	2.4 (2)	O2—C14—C15—C16	−79.11 (18)
C7—C8—C9—O1	5.1 (2)	N2—C14—C15—C16	99.01 (15)
C7—C8—C9—N1	−174.23 (14)	C14—C15—C17—C18	68.78 (18)
C9—N1—C10—C11	−172.93 (12)	C16—C15—C17—C18	−171.68 (16)
C13—N1—C10—C11	3.78 (17)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N2—H1N2···O1ⁱ	0.81 (2)	2.09 (2)	2.8789 (16)	163 (2)

Symmetry code: (i) −x+3/2, y−1/2, −z+1.

Experimental details

Crystal data
Chemical formula	C₁₈H₂₄N₂O₂
M_r	300.39
Crystal system, space group	Monoclinic, C2
Temperature (K)	100
a, b, c (Å)	18.8909 (3), 6.8398 (1), 13.4174 (2)
β (°)	107.054 (1)
V (Å³)	1657.43 (4)
Z	4
Radiation type	Cu Kα
µ (mm⁻¹)	0.63
Crystal size (mm)	0.57 × 0.16 × 0.13

Data collection
Diffractometer	Bruker APEXII DUO CCD area-detector
Absorption correction	Multi-scan (SADABS; Bruker, 2009)
T_min, T_max	0.718, 0.924
No. of measured, independent and observed [I > 2σ(I)] reflections	10656, 2625, 2606
R_int	0.042
(sin θ/λ)_max (Å⁻¹)	0.599

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.033, 0.096, 1.16
No. of reflections	2625
No. of parameters	205
No. of restraints	1
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.21, −0.27
Absolute structure	Flack (1983), 1036 Friedel pairs
Absolute structure parameter	0.03 (18)

Computer programs: APEX2 (Bruker, 2009), SAINT (Bruker, 2009), SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2009).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N2—H1N2···O1ⁱ	0.81 (2)	2.09 (2)	2.8789 (16)	163 (2)

Symmetry code: (i) −x+3/2, y−1/2, −z+1.

Footnotes

‡Thomson Reuters ResearcherID: A-3561-2009.

§Additional correspondence author, e-mail: suchada.c@psu.ac.th. Thomson Reuters ResearcherID: A-5085-2009.

Acknowledgements

OY thanks the Office of the Higher Education Commission, Thailand, for support by grant funding under the program Strategic Scholarships for Frontier Research Network for the Joint PhD Program Thai Doctoral degree. The authors thank the Thailand Research Fund (BRG5280013) and Prince of Songkla University for financial support. The authors also thank Universiti Sains Malaysia for the Research University Golden Goose grant No. 1001/PFIZIK/811012.

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