5-Meth­oxy-1,2′,3-trimethyl-4,6-dioxa-2-aza­spiro­[bicyclo­[3.2.0]hept-2-ene-7,4′-isoquinoline]-1′,3′(2′H,4′H)-dione

Fun, H.-K.; Quah, C.K.; Huang, C.; Yu, H.

doi:10.1107/S1600536811016266

organic compounds

CRYSTALLOGRAPHIC
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ISSN: 2056-9890

Volume 67| Part 6| June 2011| Pages o1340-o1341

doi:10.1107/S1600536811016266

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5-Methoxy-1,2′,3-trimethyl-4,6-dioxa-2-azaspiro[bicyclo[3.2.0]hept-2-ene-7,4′-isoquinoline]-1′,3′(2′H,4′H)-dione

Hoong-Kun Fun,^a ^*‡ Ching Kheng Quah,^a § Chengmei Huang ^b and Haitao Yu ^b

^aX-ray Crystallography Unit, School of Physics, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia, and ^bSchool of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, People's Republic of China
^*Correspondence e-mail: hkfun@usm.my

(Received 21 April 2011; accepted 29 April 2011; online 7 May 2011)

In the isoquinoline ring system of the title molecule, C₁₆H₁₆N₂O₅, the N-heterocyclic ring is in a half-boat conformation. The dioxaazaspiro ring is essentially planar [maximum deviation = 0.022 (1) Å] and forms a dihedral angle of 24.56 (4)° with the benzene ring.

Related literature

For general background to and the potential biological activity of the title compound, see: Du et al. (2008 ); Chen et al. (2006 ); Yu et al. (2010 ); Harris et al. (2005 ); Zhang et al. (2004 ); Wang et al. (2010 ); Huang et al. (2011 ). For the stability of the temperature controller used in the data collection, see: Cosier & Glazer (1986 ). For standard bond-length data, see: Allen et al. (1987 ). For ring conformations, see: Cremer & Pople (1975 ). For related structures, see: Fun et al. (2011a ,b ,c ).

Experimental

Crystal data

C₁₆H₁₆N₂O₅
M_r = 316.31
Monoclinic, P 2₁ /c
a = 7.3643 (1) Å
b = 29.8703 (6) Å
c = 6.7802 (1) Å
β = 105.294 (1)°
V = 1438.65 (4) Å³
Z = 4
Mo Kα radiation
μ = 0.11 mm⁻¹
T = 100 K
0.46 × 0.31 × 0.27 mm

Data collection

Bruker SMART APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2009 ) T_min = 0.951, T_max = 0.971
44501 measured reflections
8265 independent reflections
6842 reflections with I > 2σ(I)
R_int = 0.033

Refinement

R[F² > 2σ(F²)] = 0.049
wR(F²) = 0.126
S = 1.08
8265 reflections
212 parameters
H-atom parameters constrained
Δρ_max = 0.50 e Å⁻³
Δρ_min = −0.37 e Å⁻³

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/S1600536811016266/lh5241sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536811016266/lh5241Isup2.hkl

Supporting information file. DOI: 10.1107/S1600536811016266/lh5241Isup3.cml

checkCIF report

Comment top

Isoquinoline-1,3,4-trione derivatives have been reported to be a type of small molecular inhibitor against caspase-3 which can promote apoptosis of the cells (Du et al., 2008; Chen et al., 2006). Photoreactions of isoquinoline-1,3,4-trione could lead to structurally important motifs (Yu et al., 2010). Oxazole ring is found in some bioactive natural products such as Annuloline and Ostreogrycin A. Oxazoles can be used to inhibit the activity of malignant tumors (Harris et al., 2005). Since a lot of natural products especially the alkaloids containing isoquinoline or oxazole ring are bioactive, convenient method to construct such moieties is of current research interest (Zhang et al., 2004; Wang et al., 2010). The title compound which was derived from isoquinoline-1,3,4-trione and oxazoles (Huang et al., 2011) may has a potential use in biochemical and pharmaceutical fields. We report in this paper the crystal structure of the title compound with a relative configuration of (1S^*, 4'S^*, 5R^*).

In the title racemic compound, Fig. 1, atoms C9, C10 and C12 are the stereo centers. The isoquinoline ring system (N1/C1-C9) is not completely planar, the N-heterocyclic ring (N1/C1-C3/C8/C9) being distorted towards a half-boat conformation with atom C9 deviating by 0.231 (1) Å from the mean plane through the remaining atoms, puckering parameters (Cremer & Pople, 1975) Q = 0.3501 (8) Å, Θ = 112.83 (13)° and ϕ = 282.17 (13)°. The dioxa-2-azaspiro ring (N2/O4/C10-C12) is essentially planar [maximum deviation of 0.022 (1) Å at atom C10] and it inclines at a dihedral angle of 24.56 (4)° with the benzene ring (C3-C8). Bond lengths (Allen et al., 1987) and angles are within normal ranges and comparable to related structures (Fun et al., 2011a,b,c). In the crystal of the title compound, unlike in our previously determined structures mentioned above, there are no significant intermolecular hydrogen bonds.

Related literature top

For general background to and the potential biological activity of the title compound, see: Du et al. (2008); Chen et al. (2006); Yu et al. (2010); Harris et al. (2005); Zhang et al. (2004); Wang et al. (2010); Huang et al. (2011). For the stability of the temperature controller used in the data collection, see: Cosier & Glazer (1986). For standard bond-length data, see: Allen et al. (1987). For ring conformations, see: Cremer & Pople (1975). For related structures, see: Fun et al. (2011a,b,c).

Experimental top

The title compound was the main product from the photoreaction between isoquinoline-1,3,4-trione and 4-methyl-5-methoxy-2-methyloxazole. The compound was purified by flash column chromatography with ethyl acetate/petroleum ether (1:3) as eluents. X-ray quality crystals of the title compound was obtained from slow evaporation of an acetone and petroleum ether solution (1:4) (m.p. 437-439 K).

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 the title compound showing 50% probability displacement ellipsoids for non-H atoms.

5-Methoxy-1,2',3-trimethyl-4,6-dioxa-2-azaspiro[bicyclo[3.2.0]hept-2-ene- 7,4'-isoquinoline]-1',3'(2'H,4'H)-dione top

Crystal data top

C₁₆H₁₆N₂O₅	F(000) = 664
M_r = 316.31	D_x = 1.460 Mg m⁻³
Monoclinic, P2₁/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 9541 reflections
a = 7.3643 (1) Å	θ = 2.7–38.9°
b = 29.8703 (6) Å	µ = 0.11 mm⁻¹
c = 6.7802 (1) Å	T = 100 K
β = 105.294 (1)°	Block, colourless
V = 1438.65 (4) Å³	0.46 × 0.31 × 0.27 mm
Z = 4

Data collection top

Bruker SMART APEXII CCD area-detector diffractometer	8265 independent reflections
Radiation source: fine-focus sealed tube	6842 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.033
ϕ and ω scans	θ_max = 39.1°, θ_min = 2.7°
Absorption correction: multi-scan (SADABS; Bruker, 2009)	h = −13→11
T_min = 0.951, T_max = 0.971	k = −52→52
44501 measured reflections	l = −10→12

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)] = 0.049	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.126	H-atom parameters constrained
S = 1.08	w = 1/[σ²(F_o²) + (0.0561P)² + 0.4048P] where P = (F_o² + 2F_c²)/3
8265 reflections	(Δ/σ)_max = 0.001
212 parameters	Δρ_max = 0.50 e Å⁻³
0 restraints	Δρ_min = −0.37 e Å⁻³

Crystal data top

C₁₆H₁₆N₂O₅	V = 1438.65 (4) Å³
M_r = 316.31	Z = 4
Monoclinic, P2₁/c	Mo Kα radiation
a = 7.3643 (1) Å	µ = 0.11 mm⁻¹
b = 29.8703 (6) Å	T = 100 K
c = 6.7802 (1) Å	0.46 × 0.31 × 0.27 mm
β = 105.294 (1)°

Data collection top

Bruker SMART APEXII CCD area-detector diffractometer	8265 independent reflections
Absorption correction: multi-scan (SADABS; Bruker, 2009)	6842 reflections with I > 2σ(I)
T_min = 0.951, T_max = 0.971	R_int = 0.033
44501 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.049	0 restraints
wR(F²) = 0.126	H-atom parameters constrained
S = 1.08	Δρ_max = 0.50 e Å⁻³
8265 reflections	Δρ_min = −0.37 e Å⁻³
212 parameters

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	0.98692 (10)	0.07763 (2)	1.21672 (11)	0.01961 (12)
O2	0.97185 (10)	0.22835 (2)	1.29761 (11)	0.02036 (12)
O3	0.64272 (8)	0.074342 (18)	0.93351 (9)	0.01245 (10)
O4	0.80974 (8)	0.037356 (19)	0.72911 (9)	0.01405 (10)
O5	0.50850 (8)	0.06418 (2)	0.59672 (9)	0.01442 (10)
N1	0.99366 (9)	0.15373 (2)	1.23860 (10)	0.01288 (11)
N2	0.98329 (9)	0.10159 (2)	0.78175 (11)	0.01329 (11)
C1	0.91387 (11)	0.11323 (3)	1.15734 (11)	0.01266 (12)
C2	0.89437 (11)	0.19420 (3)	1.22005 (11)	0.01288 (12)
C3	0.68983 (10)	0.19200 (2)	1.11676 (11)	0.01123 (11)
C4	0.57505 (11)	0.22751 (2)	1.14283 (12)	0.01418 (12)
H4A	0.6279	0.2526	1.2171	0.017*
C5	0.38157 (12)	0.22526 (3)	1.05764 (13)	0.01604 (13)
H5A	0.3048	0.2489	1.0743	0.019*
C6	0.30314 (11)	0.18742 (3)	0.94723 (12)	0.01532 (13)
H6A	0.1739	0.1860	0.8893	0.018*
C7	0.41660 (11)	0.15171 (3)	0.92290 (11)	0.01323 (12)
H7A	0.3630	0.1264	0.8506	0.016*
C8	0.61080 (10)	0.15391 (2)	1.00719 (10)	0.01055 (11)
C9	0.73909 (10)	0.11699 (2)	0.97884 (11)	0.01041 (11)
C10	0.67607 (10)	0.07134 (2)	0.73762 (11)	0.01101 (11)
C11	0.98054 (11)	0.05895 (3)	0.76219 (12)	0.01374 (12)
C12	0.79021 (10)	0.11558 (2)	0.76495 (11)	0.01075 (11)
C13	0.72971 (12)	0.15463 (3)	0.62183 (12)	0.01482 (13)
H13A	0.7495	0.1475	0.4909	0.022*
H13B	0.8025	0.1806	0.6771	0.022*
H13C	0.5986	0.1607	0.6063	0.022*
C14	1.18102 (12)	0.15176 (3)	1.38319 (13)	0.01961 (15)
H14A	1.2585	0.1311	1.3338	0.029*
H14B	1.1695	0.1420	1.5143	0.029*
H14C	1.2376	0.1809	1.3961	0.029*
C15	0.51787 (13)	0.05535 (3)	0.39061 (13)	0.02037 (15)
H15A	0.3927	0.0530	0.3024	0.031*
H15B	0.5840	0.0278	0.3874	0.031*
H15C	0.5831	0.0794	0.3447	0.031*
C16	1.14282 (12)	0.02931 (3)	0.76728 (17)	0.02177 (17)
H16A	1.2575	0.0462	0.8101	0.033*
H16B	1.1314	0.0173	0.6333	0.033*
H16C	1.1448	0.0053	0.8618	0.033*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1	0.0194 (3)	0.0141 (2)	0.0220 (3)	0.0030 (2)	−0.0004 (2)	0.0036 (2)
O2	0.0186 (3)	0.0147 (3)	0.0249 (3)	−0.0053 (2)	0.0006 (2)	−0.0044 (2)
O3	0.0150 (2)	0.0102 (2)	0.0132 (2)	−0.00369 (17)	0.00555 (17)	−0.00184 (17)
O4	0.0112 (2)	0.0101 (2)	0.0215 (3)	−0.00064 (17)	0.00536 (18)	−0.00282 (18)
O5	0.0113 (2)	0.0169 (2)	0.0144 (2)	−0.00187 (18)	0.00209 (17)	−0.00453 (19)
N1	0.0106 (2)	0.0138 (3)	0.0126 (2)	−0.00073 (19)	0.00022 (18)	−0.0006 (2)
N2	0.0113 (2)	0.0118 (2)	0.0179 (3)	−0.00080 (19)	0.0059 (2)	−0.0016 (2)
C1	0.0126 (3)	0.0126 (3)	0.0121 (3)	0.0000 (2)	0.0022 (2)	0.0005 (2)
C2	0.0132 (3)	0.0125 (3)	0.0123 (3)	−0.0019 (2)	0.0022 (2)	−0.0002 (2)
C3	0.0124 (3)	0.0104 (3)	0.0106 (2)	−0.0008 (2)	0.0026 (2)	0.0001 (2)
C4	0.0174 (3)	0.0106 (3)	0.0146 (3)	0.0006 (2)	0.0044 (2)	−0.0004 (2)
C5	0.0169 (3)	0.0143 (3)	0.0176 (3)	0.0039 (2)	0.0058 (2)	0.0005 (2)
C6	0.0117 (3)	0.0175 (3)	0.0164 (3)	0.0022 (2)	0.0031 (2)	0.0001 (2)
C7	0.0113 (3)	0.0146 (3)	0.0133 (3)	0.0000 (2)	0.0022 (2)	−0.0016 (2)
C8	0.0114 (3)	0.0107 (3)	0.0095 (2)	−0.0003 (2)	0.00277 (19)	−0.0006 (2)
C9	0.0110 (3)	0.0094 (2)	0.0107 (2)	−0.0013 (2)	0.00248 (19)	−0.0008 (2)
C10	0.0104 (3)	0.0102 (3)	0.0127 (3)	−0.0006 (2)	0.0035 (2)	−0.0015 (2)
C11	0.0116 (3)	0.0123 (3)	0.0183 (3)	−0.0008 (2)	0.0056 (2)	−0.0020 (2)
C12	0.0112 (3)	0.0098 (3)	0.0117 (3)	−0.0006 (2)	0.0040 (2)	−0.0009 (2)
C13	0.0187 (3)	0.0124 (3)	0.0145 (3)	0.0010 (2)	0.0064 (2)	0.0021 (2)
C14	0.0131 (3)	0.0241 (4)	0.0178 (3)	−0.0014 (3)	−0.0026 (2)	0.0012 (3)
C15	0.0215 (4)	0.0237 (4)	0.0149 (3)	−0.0007 (3)	0.0030 (3)	−0.0056 (3)
C16	0.0140 (3)	0.0152 (3)	0.0374 (5)	0.0019 (3)	0.0092 (3)	−0.0041 (3)

Geometric parameters (Å, º) top

O1—C1	1.2116 (10)	C6—C7	1.3914 (11)
O2—C2	1.2183 (9)	C6—H6A	0.9300
O3—C10	1.4158 (9)	C7—C8	1.3946 (10)
O3—C9	1.4512 (9)	C7—H7A	0.9300
O4—C11	1.3784 (9)	C8—C9	1.4972 (10)
O4—C10	1.4257 (9)	C9—C12	1.5921 (10)
O5—C10	1.3636 (9)	C10—C12	1.5508 (10)
O5—C15	1.4416 (10)	C11—C16	1.4804 (11)
N1—C1	1.3933 (10)	C12—C13	1.5075 (10)
N1—C2	1.4012 (10)	C13—H13A	0.9600
N1—C14	1.4679 (10)	C13—H13B	0.9600
N2—C11	1.2799 (10)	C13—H13C	0.9600
N2—C12	1.4574 (10)	C14—H14A	0.9600
C1—C9	1.5206 (10)	C14—H14B	0.9600
C2—C3	1.4857 (10)	C14—H14C	0.9600
C3—C4	1.3961 (10)	C15—H15A	0.9600
C3—C8	1.3990 (10)	C15—H15B	0.9600
C4—C5	1.3907 (12)	C15—H15C	0.9600
C4—H4A	0.9300	C16—H16A	0.9600
C5—C6	1.3941 (12)	C16—H16B	0.9600
C5—H5A	0.9300	C16—H16C	0.9600

C10—O3—C9	93.33 (5)	O5—C10—O4	111.53 (6)
C11—O4—C10	105.68 (6)	O3—C10—O4	112.06 (6)
C10—O5—C15	116.23 (6)	O5—C10—C12	125.39 (6)
C1—N1—C2	123.91 (6)	O3—C10—C12	93.25 (5)
C1—N1—C14	116.97 (7)	O4—C10—C12	104.67 (6)
C2—N1—C14	118.08 (7)	N2—C11—O4	118.12 (7)
C11—N2—C12	106.79 (6)	N2—C11—C16	127.02 (7)
O1—C1—N1	121.77 (7)	O4—C11—C16	114.85 (7)
O1—C1—C9	122.53 (7)	N2—C12—C13	112.88 (6)
N1—C1—C9	115.52 (6)	N2—C12—C10	104.58 (6)
O2—C2—N1	120.65 (7)	C13—C12—C10	121.57 (6)
O2—C2—C3	122.79 (7)	N2—C12—C9	113.37 (6)
N1—C2—C3	116.38 (6)	C13—C12—C9	117.72 (6)
C4—C3—C8	120.27 (7)	C10—C12—C9	83.13 (5)
C4—C3—C2	118.63 (7)	C12—C13—H13A	109.5
C8—C3—C2	120.95 (6)	C12—C13—H13B	109.5
C5—C4—C3	119.93 (7)	H13A—C13—H13B	109.5
C5—C4—H4A	120.0	C12—C13—H13C	109.5
C3—C4—H4A	120.0	H13A—C13—H13C	109.5
C4—C5—C6	119.74 (7)	H13B—C13—H13C	109.5
C4—C5—H5A	120.1	N1—C14—H14A	109.5
C6—C5—H5A	120.1	N1—C14—H14B	109.5
C7—C6—C5	120.57 (7)	H14A—C14—H14B	109.5
C7—C6—H6A	119.7	N1—C14—H14C	109.5
C5—C6—H6A	119.7	H14A—C14—H14C	109.5
C6—C7—C8	119.88 (7)	H14B—C14—H14C	109.5
C6—C7—H7A	120.1	O5—C15—H15A	109.5
C8—C7—H7A	120.1	O5—C15—H15B	109.5
C7—C8—C3	119.60 (7)	H15A—C15—H15B	109.5
C7—C8—C9	121.75 (6)	O5—C15—H15C	109.5
C3—C8—C9	118.62 (6)	H15A—C15—H15C	109.5
O3—C9—C8	112.58 (6)	H15B—C15—H15C	109.5
O3—C9—C1	111.58 (6)	C11—C16—H16A	109.5
C8—C9—C1	112.49 (6)	C11—C16—H16B	109.5
O3—C9—C12	90.22 (5)	H16A—C16—H16B	109.5
C8—C9—C12	116.44 (6)	C11—C16—H16C	109.5
C1—C9—C12	111.66 (6)	H16A—C16—H16C	109.5
O5—C10—O3	108.56 (6)	H16B—C16—H16C	109.5

C2—N1—C1—O1	−161.40 (8)	O1—C1—C9—C12	−81.94 (9)
C14—N1—C1—O1	6.68 (11)	N1—C1—C9—C12	93.26 (7)
C2—N1—C1—C9	23.35 (10)	C15—O5—C10—O3	−173.45 (6)
C14—N1—C1—C9	−168.56 (7)	C15—O5—C10—O4	−49.51 (9)
C1—N1—C2—O2	178.82 (8)	C15—O5—C10—C12	78.38 (9)
C14—N1—C2—O2	10.86 (11)	C9—O3—C10—O5	−126.97 (6)
C1—N1—C2—C3	3.52 (10)	C9—O3—C10—O4	109.41 (6)
C14—N1—C2—C3	−164.44 (7)	C9—O3—C10—C12	2.15 (6)
O2—C2—C3—C4	−12.66 (11)	C11—O4—C10—O5	142.09 (6)
N1—C2—C3—C4	162.54 (7)	C11—O4—C10—O3	−95.97 (7)
O2—C2—C3—C8	171.75 (7)	C11—O4—C10—C12	3.77 (7)
N1—C2—C3—C8	−13.05 (10)	C12—N2—C11—O4	0.91 (9)
C8—C3—C4—C5	−0.74 (11)	C12—N2—C11—C16	179.69 (8)
C2—C3—C4—C5	−176.36 (7)	C10—O4—C11—N2	−3.21 (9)
C3—C4—C5—C6	0.27 (12)	C10—O4—C11—C16	177.86 (7)
C4—C5—C6—C7	0.53 (12)	C11—N2—C12—C13	−132.59 (7)
C5—C6—C7—C8	−0.85 (12)	C11—N2—C12—C10	1.60 (8)
C6—C7—C8—C3	0.38 (11)	C11—N2—C12—C9	90.33 (7)
C6—C7—C8—C9	−177.87 (7)	O5—C10—C12—N2	−133.99 (7)
C4—C3—C8—C7	0.41 (10)	O3—C10—C12—N2	110.46 (6)
C2—C3—C8—C7	175.93 (7)	O4—C10—C12—N2	−3.35 (7)
C4—C3—C8—C9	178.71 (7)	O5—C10—C12—C13	−4.83 (10)
C2—C3—C8—C9	−5.77 (10)	O3—C10—C12—C13	−120.39 (7)
C10—O3—C9—C8	116.84 (6)	O4—C10—C12—C13	125.81 (7)
C10—O3—C9—C1	−115.57 (6)	O5—C10—C12—C9	113.59 (7)
C10—O3—C9—C12	−2.09 (5)	O3—C10—C12—C9	−1.97 (5)
C7—C8—C9—O3	−23.21 (9)	O4—C10—C12—C9	−115.78 (6)
C3—C8—C9—O3	158.52 (6)	O3—C9—C12—N2	−101.04 (6)
C7—C8—C9—C1	−150.32 (7)	C8—C9—C12—N2	143.45 (6)
C3—C8—C9—C1	31.42 (9)	C1—C9—C12—N2	12.37 (8)
C7—C8—C9—C12	78.99 (8)	O3—C9—C12—C13	124.09 (7)
C3—C8—C9—C12	−99.28 (7)	C8—C9—C12—C13	8.58 (9)
O1—C1—C9—O3	17.35 (10)	C1—C9—C12—C13	−122.51 (7)
N1—C1—C9—O3	−167.44 (6)	O3—C9—C12—C10	1.92 (5)
O1—C1—C9—C8	144.99 (8)	C8—C9—C12—C10	−113.59 (6)
N1—C1—C9—C8	−39.81 (9)	C1—C9—C12—C10	115.32 (6)

Experimental details

Crystal data
Chemical formula	C₁₆H₁₆N₂O₅
M_r	316.31
Crystal system, space group	Monoclinic, P2₁/c
Temperature (K)	100
a, b, c (Å)	7.3643 (1), 29.8703 (6), 6.7802 (1)
β (°)	105.294 (1)
V (Å³)	1438.65 (4)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.11
Crystal size (mm)	0.46 × 0.31 × 0.27

Data collection
Diffractometer	Bruker SMART APEXII CCD area-detector diffractometer
Absorption correction	Multi-scan (SADABS; Bruker, 2009)
T_min, T_max	0.951, 0.971
No. of measured, independent and observed [I > 2σ(I)] reflections	44501, 8265, 6842
R_int	0.033
(sin θ/λ)_max (Å⁻¹)	0.887

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.049, 0.126, 1.08
No. of reflections	8265
No. of parameters	212
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.50, −0.37

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

Footnotes

‡Thomson Reuters ResearcherID: A-3561-2009.

§Thomson Reuters ResearcherID: A-5525-2009.

Acknowledgements

HKF and CKQ thank Universiti Sains Malaysia for the Research University Grant (No. 1001/PFIZIK/811160). Financial support from the Program for New Century Excellent Talents in Universities (NCET-08-0271) of China is also acknowledged.

References

Allen, F. H., Kennard, O., Watson, D. G., Brammer, L., Orpen, A. G. & Taylor, R. (1987). J. Chem. Soc. Perkin Trans. 2, pp. S1–19. CrossRef Web of Science Google Scholar
Bruker (2009). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Chen, Y.-H., Zhang, Y.-H., Zhang, H.-J., Liu, D.-Z., Gu, M., Li, J.-Y., Wu, F., Zhu, X.-Z., Li, J. & Nan, F.-J. (2006). J. Med. Chem. 49, 1613–1623. Web of Science CrossRef PubMed CAS Google Scholar
Cosier, J. & Glazer, A. M. (1986). J. Appl. Cryst. 19, 105–107. CrossRef CAS Web of Science IUCr Journals Google Scholar
Cremer, D. & Pople, J. A. (1975). J. Am. Chem. Soc. 97, 1354–1358. CrossRef CAS Web of Science Google Scholar
Du, J.-Q., Wu, J., Zhang, H.-J., Zhang, Y.-H., Qiu, B.-Y., Wu, F., Chen, Y.-H., Li, J.-Y., Nan, F.-J., Ding, J.-P. & Li, J. (2008). Biol. Chem. 283, 30205–30215. CrossRef CAS Google Scholar
Fun, H.-K., Quah, C. K., Huang, C. & Yu, H. (2011a). Acta Cryst. E67, o1271–o1272. Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
Fun, H.-K., Quah, C. K., Huang, C. & Yu, H. (2011b). Acta Cryst. E67, o1272–o1273. Google Scholar
Fun, H.-K., Quah, C. K., Huang, C. & Yu, H. (2011c). Acta Cryst. E67, o1311–o1312. Web of Science CSD CrossRef IUCr Journals Google Scholar
Harris, P. A., Cheung, M., Hunter, R. N., Brown, M. L., Veal, J. M., Nolte, R. T., Wang, L., Liu, W., Crosby, R. M., Johnson, J. H., Epperly, A. H., Kumar, R., Luttrell, D. K. & Stafford, J. A. (2005). J. Med. Chem. 48, 1610–1619. Web of Science CrossRef PubMed CAS Google Scholar
Huang, C., Yu, H., Miao, Z., Zhou, J., Wang, S., Fun, H.-K., Xu, J. & Zhang, Y. (2011). Org. Biomol. Chem. 9 3629–3631. Web of Science CSD CrossRef CAS PubMed Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Spek, A. L. (2009). Acta Cryst. D65, 148–155. Web of Science CrossRef CAS IUCr Journals Google Scholar
Wang, L., Huang, Y. C., Liu, Y., Fun, H.-K., Zhang, Y. & Xu, J. H. (2010). J. Org. Chem. 75, 7757–7768. Web of Science CSD CrossRef CAS PubMed Google Scholar
Yu, H., Li, J., Kou, Z., Du, X., Wei, Y., Fun, H.-K., Xu, J. & Zhang, Y. (2010). J. Org. Chem. 75, 2989–3001. Web of Science CSD CrossRef CAS PubMed Google Scholar
Zhang, Y., Wang, L., Zhang, M., Fun, H.-K. & Xu, J.-X. (2004). Org. Lett. 6, 4893–4895. Web of Science CSD CrossRef PubMed CAS Google Scholar

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