Ethyl 1-sec-butyl-2-(4-methoxy­phen­yl)-1H-benzimidazole-5-carboxyl­ate

Arumugam, N.; Abdul Rahim, A.S.; Osman, H.; Hemamalini, M.; Fun, H.-K.

doi:10.1107/S1600536810007634

organic compounds

CRYSTALLOGRAPHIC
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ISSN: 2056-9890

Volume 66| Part 4| April 2010| Page o845

doi:10.1107/S1600536810007634

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Ethyl 1-sec-butyl-2-(4-methoxyphenyl)-1H-benzimidazole-5-carboxylate

Natarajan Arumugam,^a Aisyah Saad Abdul Rahim,^a ‡ Hasnah Osman,^b Madhukar Hemamalini ^c and Hoong-Kun Fun ^c ^*§

^aSchool of Pharmaceutical Sciences, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia, ^bSchool of Chemical Sciences, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia, and ^cX-ray Crystallography Unit, School of Physics, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia
^*Correspondence e-mail: hkfun@usm.my

(Received 24 February 2010; accepted 1 March 2010; online 17 March 2010)

In the title molecule, C₂₁H₂₄N₂O₃, the dihedral angle between the benzene and imidazole rings is 66.33 (13)°. The imidazole ring is essentially planar, with a maximum deviation of 0.004 (2) Å. In the crystal structure, molecules are connected by weak C—H⋯O hydrogen bonds, forming chains along the b axis

Related literature

For the benzimidazole nucleus as a key building block for compounds showing biologically activity, see: Tanious et al. (2004 ). For the therapeutic properties of benzimidazole derivatives, see: Kohara et al. (1996 ); Mader et al. (2008 ). For 2-substituted-phenylbenzimidazoles with biological activity, see: Coburn et al. (1987 ); Roth et al. (1997 ).

Experimental

Crystal data

C₂₁H₂₄N₂O₃
M_r = 352.42
Monoclinic, P 2₁ /c
a = 10.5815 (3) Å
b = 12.1079 (3) Å
c = 15.1050 (3) Å
β = 93.678 (2)°
V = 1931.26 (8) Å³
Z = 4
Mo Kα radiation
μ = 0.08 mm⁻¹
T = 296 K
0.40 × 0.31 × 0.07 mm

Data collection

Bruker SMART APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2009 ) T_min = 0.968, T_max = 0.994
19216 measured reflections
4437 independent reflections
2266 reflections with I > 2s(I)
R_int = 0.065

Refinement

R[F² > 2σ(F²)] = 0.066
wR(F²) = 0.150
S = 1.04
4437 reflections
235 parameters
H-atom parameters constrained
Δρ_max = 0.13 e Å⁻³
Δρ_min = −0.18 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C21—H21C⋯O1ⁱ	0.96	2.47	3.389 (4)	161
Symmetry code: (i) $[-x, y-{\script{1\over 2}}, -z+{\script{1\over 2}}]$ .

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: 10.1107/S1600536810007634/tk2635sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536810007634/tk2635Isup2.hkl

checkCIF report

Comment top

The benzimidazole nucleus is the key building block for a variety of compounds that play crucial roles in the function of a number of biologically important molecules (Tanious et al., 2004). Benzimidazole derivatives have shown different therapeutic properties such as antihypertensive (Kohara et al., 1996) and anti-inflammatory (Mader et al., 2008) activities. 2-(substitutedphenyl)benzimidazoles with various types of biological activities, such as antibacterial (Coburn et al., 1987) and antiviral (Roth et al., 1997), have been reported. Due to their importance, the crystal structure determination of the title compound was carried out and the results are presented here.

In the title molecule (Fig. 1), the imidazole ring is essentially planar with a maximum deviation of 0.004 (2) Å for atom C13. The dihedral angle between the imidazole ring (N1/N2/C13/C7–C8) and the benzene ring (C1–C6) is 66.33 (13)° . In the crystal structure (Fig. 2), the molecules are connected by weak C21—H21C···O1 (Table 1) hydrogen bonds, forming one-dimensional chains along the b axis.

Related literature top

For the benzimidazole nucleus as a key building block for compounds showing biologically activity, see: Tanious et al. (2004). For the therapeutic properties of benzimidazole derivatives, see: Kohara et al. (1996); Mader et al. (2008). For 2-(substitutedphenyl)benzimidazoles with biological activity, see: Coburn et al. (1987); Roth et al. (1997).

Experimental top

Ethyl-3-amino-4-(sec-butylamino)benzoate (200 mg, 0.84 mmol) and the sodium metabisulfite adduct of 4-methoxy benzaldehyde (406 mg, 1.68 mmol) were dissolved in DMF. The reaction mixture was irradiated under microwave conditions at 403 K for 2 minutes. After completion of the reaction, the reaction mixture was diluted in EtOAc (20 ml) and washed with H₂O (20 ml). The organic layer was collected, dried over Na₂SO₄ and then evaporated in vacuo to yield the crude product. The product was recrystallized from hot EtOAc to afford the title compound as colorless crystals.

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 title molecule, showing 50% probability displacement ellipsoids and the atom-numbering scheme.
	Fig. 2. A view of the crystal packing of the title compound, showing C–H···O interactions as dashed lines. H atoms not involved in the hydrogen bond interactions are omitted for clarity.

Ethyl 1-sec-butyl-2-(4-methoxyphenyl)-1H-benzimidazole-5-carboxylate top

Crystal data top

C₂₁H₂₄N₂O₃	F(000) = 752
M_r = 352.42	D_x = 1.212 Mg m⁻³
Monoclinic, P2₁/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 1865 reflections
a = 10.5815 (3) Å	θ = 2.6–19.8°
b = 12.1079 (3) Å	µ = 0.08 mm⁻¹
c = 15.1050 (3) Å	T = 296 K
β = 93.678 (2)°	Plate, colourless
V = 1931.26 (8) Å³	0.40 × 0.31 × 0.07 mm
Z = 4

Data collection top

Bruker SMART APEXII CCD area-detector diffractometer	4437 independent reflections
Radiation source: fine-focus sealed tube	2266 reflections with I > 2s(I)
Graphite monochromator	R_int = 0.065
ϕ and ω scans	θ_max = 27.5°, θ_min = 1.9°
Absorption correction: multi-scan (SADABS; Bruker, 2009)	h = −13→13
T_min = 0.968, T_max = 0.994	k = −15→15
19216 measured reflections	l = −19→19

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)] = 0.066	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.150	H-atom parameters constrained
S = 1.04	w = 1/[σ²(F_o²) + (0.0461P)² + 0.4985P] where P = (F_o² + 2F_c²)/3
4437 reflections	(Δ/σ)_max < 0.001
235 parameters	Δρ_max = 0.13 e Å⁻³
0 restraints	Δρ_min = −0.18 e Å⁻³

Crystal data top

C₂₁H₂₄N₂O₃	V = 1931.26 (8) Å³
M_r = 352.42	Z = 4
Monoclinic, P2₁/c	Mo Kα radiation
a = 10.5815 (3) Å	µ = 0.08 mm⁻¹
b = 12.1079 (3) Å	T = 296 K
c = 15.1050 (3) Å	0.40 × 0.31 × 0.07 mm
β = 93.678 (2)°

Data collection top

Bruker SMART APEXII CCD area-detector diffractometer	4437 independent reflections
Absorption correction: multi-scan (SADABS; Bruker, 2009)	2266 reflections with I > 2s(I)
T_min = 0.968, T_max = 0.994	R_int = 0.065
19216 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.066	0 restraints
wR(F²) = 0.150	H-atom parameters constrained
S = 1.04	Δρ_max = 0.13 e Å⁻³
4437 reflections	Δρ_min = −0.18 e Å⁻³
235 parameters

Special details top

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	0.50185 (18)	0.95365 (16)	0.17576 (12)	0.0728 (6)
O2	0.34173 (18)	1.00924 (15)	0.08352 (13)	0.0735 (6)
O3	−0.47540 (19)	0.38119 (16)	0.08035 (13)	0.0761 (6)
N1	0.07745 (19)	0.58199 (16)	0.20122 (13)	0.0503 (5)
N2	0.00579 (19)	0.70718 (16)	0.10000 (13)	0.0532 (5)
C1	−0.2515 (2)	0.5992 (2)	0.15122 (17)	0.0587 (7)
H1A	−0.2505	0.6692	0.1767	0.070*
C2	−0.3657 (3)	0.5442 (2)	0.13763 (16)	0.0594 (7)
H2A	−0.4402	0.5765	0.1543	0.071*
C3	−0.3678 (3)	0.4410 (2)	0.09909 (16)	0.0570 (7)
C4	−0.2565 (3)	0.3940 (2)	0.07547 (19)	0.0696 (8)
H4A	−0.2578	0.3243	0.0495	0.084*
C5	−0.1438 (3)	0.4490 (2)	0.08990 (18)	0.0651 (8)
H5A	−0.0693	0.4159	0.0739	0.078*
C6	−0.1391 (2)	0.5534 (2)	0.12809 (15)	0.0491 (6)
C7	−0.0199 (2)	0.6160 (2)	0.14217 (16)	0.0481 (6)
C8	0.1732 (2)	0.65916 (19)	0.19625 (15)	0.0478 (6)
C9	0.2938 (2)	0.6692 (2)	0.23777 (17)	0.0598 (7)
H9A	0.3260	0.6164	0.2779	0.072*
C10	0.3633 (2)	0.7602 (2)	0.21706 (17)	0.0563 (7)
H10A	0.4438	0.7693	0.2445	0.068*
C11	0.3174 (2)	0.8402 (2)	0.15602 (15)	0.0485 (6)
C12	0.1987 (2)	0.8284 (2)	0.11322 (16)	0.0509 (6)
H12A	0.1677	0.8803	0.0720	0.061*
C13	0.1265 (2)	0.73630 (19)	0.13359 (15)	0.0452 (6)
C14	0.3975 (3)	0.9378 (2)	0.14099 (17)	0.0548 (7)
C15	0.4123 (3)	1.1098 (2)	0.0663 (2)	0.0797 (9)
H15A	0.4977	1.0918	0.0515	0.096*
H15B	0.4170	1.1571	0.1183	0.096*
C16	0.3432 (3)	1.1663 (3)	−0.0091 (2)	0.0928 (10)
H16A	0.3872	1.2328	−0.0229	0.139*
H16B	0.2592	1.1843	0.0067	0.139*
H16C	0.3385	1.1184	−0.0598	0.139*
C17	0.0678 (3)	0.4949 (2)	0.26963 (17)	0.0600 (7)
H17A	−0.0174	0.4634	0.2602	0.072*
C18	0.0755 (3)	0.5434 (3)	0.36209 (18)	0.0758 (9)
H18A	0.0617	0.4847	0.4041	0.091*
H18B	0.1605	0.5715	0.3751	0.091*
C19	−0.0167 (3)	0.6342 (3)	0.3763 (2)	0.0972 (11)
H19A	−0.0046	0.6609	0.4361	0.146*
H19B	−0.1015	0.6067	0.3662	0.146*
H19C	−0.0033	0.6934	0.3357	0.146*
C20	0.1589 (3)	0.4015 (2)	0.2570 (2)	0.0830 (10)
H20A	0.1475	0.3744	0.1973	0.124*
H20B	0.1432	0.3430	0.2977	0.124*
H20C	0.2442	0.4276	0.2678	0.124*
C21	−0.5922 (3)	0.4267 (3)	0.1060 (2)	0.0828 (10)
H21A	−0.6601	0.3767	0.0894	0.124*
H21B	−0.6072	0.4962	0.0766	0.124*
H21C	−0.5877	0.4376	0.1690	0.124*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1	0.0634 (13)	0.0789 (14)	0.0747 (13)	−0.0233 (11)	−0.0070 (11)	0.0058 (10)
O2	0.0746 (13)	0.0553 (12)	0.0884 (14)	−0.0213 (10)	−0.0109 (11)	0.0173 (10)
O3	0.0636 (13)	0.0762 (14)	0.0884 (14)	−0.0216 (11)	0.0039 (10)	−0.0165 (11)
N1	0.0537 (13)	0.0410 (12)	0.0558 (12)	−0.0019 (10)	−0.0002 (10)	0.0107 (9)
N2	0.0560 (14)	0.0466 (12)	0.0557 (13)	−0.0065 (10)	−0.0052 (10)	0.0079 (10)
C1	0.0655 (18)	0.0428 (15)	0.0685 (18)	−0.0067 (14)	0.0085 (14)	−0.0055 (12)
C2	0.0556 (17)	0.0565 (17)	0.0668 (17)	−0.0023 (14)	0.0091 (13)	−0.0005 (14)
C3	0.0616 (18)	0.0545 (17)	0.0547 (15)	−0.0136 (15)	0.0015 (13)	−0.0006 (13)
C4	0.0677 (19)	0.0530 (17)	0.088 (2)	−0.0092 (16)	0.0052 (16)	−0.0216 (15)
C5	0.0599 (18)	0.0529 (17)	0.083 (2)	−0.0005 (15)	0.0062 (15)	−0.0119 (15)
C6	0.0534 (16)	0.0412 (14)	0.0524 (14)	−0.0027 (13)	0.0010 (12)	0.0048 (12)
C7	0.0520 (15)	0.0425 (14)	0.0498 (14)	−0.0003 (12)	0.0039 (12)	0.0028 (11)
C8	0.0496 (15)	0.0411 (14)	0.0527 (14)	−0.0007 (12)	0.0032 (12)	0.0026 (11)
C9	0.0554 (17)	0.0533 (17)	0.0699 (18)	0.0026 (14)	−0.0035 (14)	0.0114 (13)
C10	0.0494 (16)	0.0539 (17)	0.0643 (17)	−0.0004 (13)	−0.0050 (13)	0.0020 (13)
C11	0.0500 (15)	0.0440 (14)	0.0516 (14)	−0.0031 (12)	0.0050 (12)	−0.0023 (11)
C12	0.0575 (16)	0.0440 (15)	0.0506 (14)	−0.0013 (13)	−0.0005 (12)	0.0055 (11)
C13	0.0492 (15)	0.0399 (14)	0.0462 (14)	0.0016 (12)	0.0002 (11)	0.0005 (11)
C14	0.0575 (17)	0.0539 (17)	0.0531 (16)	−0.0077 (14)	0.0042 (14)	−0.0047 (13)
C15	0.092 (2)	0.0582 (19)	0.087 (2)	−0.0277 (17)	−0.0076 (18)	0.0144 (16)
C16	0.111 (3)	0.072 (2)	0.095 (2)	−0.022 (2)	0.003 (2)	0.0107 (19)
C17	0.0638 (17)	0.0486 (15)	0.0672 (18)	−0.0039 (14)	0.0018 (14)	0.0196 (13)
C18	0.081 (2)	0.083 (2)	0.0640 (19)	−0.0050 (18)	0.0050 (16)	0.0213 (16)
C19	0.108 (3)	0.110 (3)	0.074 (2)	0.020 (2)	0.0124 (19)	−0.008 (2)
C20	0.079 (2)	0.0545 (18)	0.116 (3)	0.0092 (17)	0.0115 (19)	0.0259 (17)
C21	0.063 (2)	0.107 (3)	0.078 (2)	−0.0206 (19)	0.0052 (16)	−0.0121 (19)

Geometric parameters (Å, º) top

O1—C14	1.208 (3)	C10—H10A	0.9300
O2—C14	1.335 (3)	C11—C12	1.383 (3)
O2—C15	1.461 (3)	C11—C14	1.481 (3)
O3—C3	1.363 (3)	C12—C13	1.396 (3)
O3—C21	1.429 (3)	C12—H12A	0.9300
N1—C7	1.381 (3)	C15—C16	1.480 (4)
N1—C8	1.384 (3)	C15—H15A	0.9700
N1—C17	1.485 (3)	C15—H15B	0.9700
N2—C7	1.312 (3)	C16—H16A	0.9600
N2—C13	1.389 (3)	C16—H16B	0.9600
C1—C6	1.377 (3)	C16—H16C	0.9600
C1—C2	1.384 (3)	C17—C20	1.507 (4)
C1—H1A	0.9300	C17—C18	1.512 (4)
C2—C3	1.379 (4)	C17—H17A	0.9800
C2—H2A	0.9300	C18—C19	1.495 (4)
C3—C4	1.375 (4)	C18—H18A	0.9700
C4—C5	1.372 (4)	C18—H18B	0.9700
C4—H4A	0.9300	C19—H19A	0.9600
C5—C6	1.389 (3)	C19—H19B	0.9600
C5—H5A	0.9300	C19—H19C	0.9600
C6—C7	1.475 (3)	C20—H20A	0.9600
C8—C9	1.391 (3)	C20—H20B	0.9600
C8—C13	1.397 (3)	C20—H20C	0.9600
C9—C10	1.373 (3)	C21—H21A	0.9600
C9—H9A	0.9300	C21—H21B	0.9600
C10—C11	1.402 (3)	C21—H21C	0.9600

C14—O2—C15	116.5 (2)	O1—C14—O2	122.2 (2)
C3—O3—C21	117.7 (2)	O1—C14—C11	125.2 (3)
C7—N1—C8	106.39 (19)	O2—C14—C11	112.6 (2)
C7—N1—C17	125.4 (2)	O2—C15—C16	106.8 (2)
C8—N1—C17	126.9 (2)	O2—C15—H15A	110.4
C7—N2—C13	104.5 (2)	C16—C15—H15A	110.4
C6—C1—C2	121.9 (2)	O2—C15—H15B	110.4
C6—C1—H1A	119.0	C16—C15—H15B	110.4
C2—C1—H1A	119.0	H15A—C15—H15B	108.6
C3—C2—C1	119.3 (2)	C15—C16—H16A	109.5
C3—C2—H2A	120.3	C15—C16—H16B	109.5
C1—C2—H2A	120.3	H16A—C16—H16B	109.5
O3—C3—C4	116.4 (2)	C15—C16—H16C	109.5
O3—C3—C2	124.0 (3)	H16A—C16—H16C	109.5
C4—C3—C2	119.6 (3)	H16B—C16—H16C	109.5
C5—C4—C3	120.5 (3)	N1—C17—C20	111.8 (2)
C5—C4—H4A	119.7	N1—C17—C18	111.4 (2)
C3—C4—H4A	119.7	C20—C17—C18	114.3 (2)
C4—C5—C6	121.0 (3)	N1—C17—H17A	106.2
C4—C5—H5A	119.5	C20—C17—H17A	106.2
C6—C5—H5A	119.5	C18—C17—H17A	106.2
C1—C6—C5	117.6 (2)	C19—C18—C17	114.9 (2)
C1—C6—C7	120.1 (2)	C19—C18—H18A	108.5
C5—C6—C7	122.3 (2)	C17—C18—H18A	108.5
N2—C7—N1	113.3 (2)	C19—C18—H18B	108.5
N2—C7—C6	124.3 (2)	C17—C18—H18B	108.5
N1—C7—C6	122.4 (2)	H18A—C18—H18B	107.5
N1—C8—C9	133.5 (2)	C18—C19—H19A	109.5
N1—C8—C13	105.1 (2)	C18—C19—H19B	109.5
C9—C8—C13	121.4 (2)	H19A—C19—H19B	109.5
C10—C9—C8	117.2 (2)	C18—C19—H19C	109.5
C10—C9—H9A	121.4	H19A—C19—H19C	109.5
C8—C9—H9A	121.4	H19B—C19—H19C	109.5
C9—C10—C11	122.4 (2)	C17—C20—H20A	109.5
C9—C10—H10A	118.8	C17—C20—H20B	109.5
C11—C10—H10A	118.8	H20A—C20—H20B	109.5
C12—C11—C10	120.2 (2)	C17—C20—H20C	109.5
C12—C11—C14	121.5 (2)	H20A—C20—H20C	109.5
C10—C11—C14	118.3 (2)	H20B—C20—H20C	109.5
C11—C12—C13	118.2 (2)	O3—C21—H21A	109.5
C11—C12—H12A	120.9	O3—C21—H21B	109.5
C13—C12—H12A	120.9	H21A—C21—H21B	109.5
N2—C13—C12	128.7 (2)	O3—C21—H21C	109.5
N2—C13—C8	110.8 (2)	H21A—C21—H21C	109.5
C12—C13—C8	120.5 (2)	H21B—C21—H21C	109.5

C6—C1—C2—C3	−0.6 (4)	C13—C8—C9—C10	2.4 (4)
C21—O3—C3—C4	178.6 (2)	C8—C9—C10—C11	−0.8 (4)
C21—O3—C3—C2	−2.9 (4)	C9—C10—C11—C12	−0.8 (4)
C1—C2—C3—O3	−178.0 (2)	C9—C10—C11—C14	177.5 (2)
C1—C2—C3—C4	0.5 (4)	C10—C11—C12—C13	0.9 (3)
O3—C3—C4—C5	178.6 (3)	C14—C11—C12—C13	−177.3 (2)
C2—C3—C4—C5	0.0 (4)	C7—N2—C13—C12	−178.3 (2)
C3—C4—C5—C6	−0.4 (4)	C7—N2—C13—C8	0.8 (3)
C2—C1—C6—C5	0.2 (4)	C11—C12—C13—N2	179.7 (2)
C2—C1—C6—C7	178.8 (2)	C11—C12—C13—C8	0.6 (3)
C4—C5—C6—C1	0.3 (4)	N1—C8—C13—N2	−0.6 (3)
C4—C5—C6—C7	−178.3 (3)	C9—C8—C13—N2	178.5 (2)
C13—N2—C7—N1	−0.7 (3)	N1—C8—C13—C12	178.6 (2)
C13—N2—C7—C6	−179.7 (2)	C9—C8—C13—C12	−2.3 (4)
C8—N1—C7—N2	0.3 (3)	C15—O2—C14—O1	−1.6 (4)
C17—N1—C7—N2	168.1 (2)	C15—O2—C14—C11	178.4 (2)
C8—N1—C7—C6	179.4 (2)	C12—C11—C14—O1	−179.9 (2)
C17—N1—C7—C6	−12.9 (4)	C10—C11—C14—O1	1.9 (4)
C1—C6—C7—N2	−66.1 (3)	C12—C11—C14—O2	0.1 (3)
C5—C6—C7—N2	112.4 (3)	C10—C11—C14—O2	−178.1 (2)
C1—C6—C7—N1	114.9 (3)	C14—O2—C15—C16	170.8 (2)
C5—C6—C7—N1	−66.5 (3)	C7—N1—C17—C20	120.4 (3)
C7—N1—C8—C9	−178.8 (3)	C8—N1—C17—C20	−74.4 (3)
C17—N1—C8—C9	13.8 (4)	C7—N1—C17—C18	−110.3 (3)
C7—N1—C8—C13	0.2 (2)	C8—N1—C17—C18	54.9 (3)
C17—N1—C8—C13	−167.3 (2)	N1—C17—C18—C19	53.6 (3)
N1—C8—C9—C10	−178.9 (2)	C20—C17—C18—C19	−178.5 (3)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C21—H21C···O1ⁱ	0.96	2.47	3.389 (4)	161

Symmetry code: (i) −x, y−1/2, −z+1/2.

Experimental details

Crystal data
Chemical formula	C₂₁H₂₄N₂O₃
M_r	352.42
Crystal system, space group	Monoclinic, P2₁/c
Temperature (K)	296
a, b, c (Å)	10.5815 (3), 12.1079 (3), 15.1050 (3)
β (°)	93.678 (2)
V (Å³)	1931.26 (8)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.08
Crystal size (mm)	0.40 × 0.31 × 0.07

Data collection
Diffractometer	Bruker SMART APEXII CCD area-detector diffractometer
Absorption correction	Multi-scan (SADABS; Bruker, 2009)
T_min, T_max	0.968, 0.994
No. of measured, independent and observed [I > 2s(I)] reflections	19216, 4437, 2266
R_int	0.065
(sin θ/λ)_max (Å⁻¹)	0.650

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.066, 0.150, 1.04
No. of reflections	4437
No. of parameters	235
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.13, −0.18

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
C21—H21C···O1ⁱ	0.9600	2.4700	3.389 (4)	161.00

Symmetry code: (i) −x, y−1/2, −z+1/2.

Footnotes

‡Additional correspondence author, e-mail: aisyah@usm.my.

§Thomson Reuters ResearcherID: A-3561-2009.

Acknowledgements

NA, ASAR and HO are grateful to Universiti Sains Malaysia (USM) for funding the synthetic chemistry research under the USM Research University grant (1001/PFARMASI/815026). NA thanks USM for the award of postdoctoral fellowship. HKF and MH thank the Malaysian Government and USM for the Research University Golden Goose grant No. 1001/PFIZIK/811012. MH also thanks USM for a post-doctoral research fellowship.

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