4-[(2,4-Dimethyl-1,3-oxazol-5-yl)meth­yl]-4-hydr­oxy-2-methyl­isoquinoline-1,3(2H,4H)-dione

Fun, H.-K.; Goh, J.H.; Yu, H.; Zhang, Y.

doi:10.1107/S1600536810007397

organic compounds

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ISSN: 2056-9890

Volume 66| Part 4| April 2010| Pages o724-o725

doi:10.1107/S1600536810007397

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4-[(2,4-Dimethyl-1,3-oxazol-5-yl)methyl]-4-hydroxy-2-methylisoquinoline-1,3(2H,4H)-dione

Hoong-Kun Fun,^a ^*‡ Jia Hao Goh,^a § Haitao Yu ^b and Yan Zhang ^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 24 February 2010; accepted 26 February 2010; online 3 March 2010)

In the title isoquinolinedione derivative, C₁₆H₁₆N₂O₄, the piperidine ring in the tetrahydroisoquinoline unit adopts a half-boat conformation. The essentially planar oxazole ring [maximum deviation = 0.004 (2) Å] is inclined at a dihedral angle of 36.00 (8)° to the tetrahydroisoquinoline unit. In the crystal structure, pairs of intermolecular C—H⋯O and O—H⋯N interactions link the molecules into chains incorporating R₂²(9) ring motifs. Two neighbouring chains are further interconnected by intermolecular C—H⋯O interactions into chains two molecules wide along the a axis.

Related literature

For general background to and applications of the title isoquinoline compound, see: Chen et al. (2006 ); Hall et al. (1994 ); Malamas & Hohman (1994 ); Mitchell et al. (1995 , 2000 ). For ring conformations, see: Cremer & Pople (1975 ). For hydrogen-bond motifs, see: Bernstein et al. (1995 ). For related structures, see: Subbiah Pandi et al. (2002 ); Wang et al. (2000 ). For bond-length data, see: Allen et al. (1987 ). For the stability of the temperature controller used for the data collection, see: Cosier & Glazer (1986 ).

Experimental

Crystal data

C₁₆H₁₆N₂O₄
M_r = 300.31
Triclinic, $[P \overline 1]$
a = 8.3866 (5) Å
b = 8.8044 (5) Å
c = 10.6734 (7) Å
α = 103.997 (3)°
β = 90.025 (3)°
γ = 112.663 (2)°
V = 701.80 (7) Å³
Z = 2
Mo Kα radiation
μ = 0.10 mm⁻¹
T = 100 K
0.24 × 0.19 × 0.08 mm

Data collection

Bruker SMART APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2009 ) T_min = 0.976, T_max = 0.992
6623 measured reflections
3198 independent reflections
2401 reflections with I > 2σ(I)
R_int = 0.034

Refinement

R[F² > 2σ(F²)] = 0.050
wR(F²) = 0.135
S = 1.04
3198 reflections
263 parameters
All H-atom parameters refined
Δρ_max = 0.40 e Å⁻³
Δρ_min = −0.28 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O3—H1O3⋯N2ⁱ	0.87 (3)	2.04 (3)	2.847 (2)	153 (3)
C16—H16A⋯O1ⁱⁱ	0.96 (3)	2.28 (3)	3.162 (2)	153 (2)
C16—H16B⋯O1ⁱⁱⁱ	1.01 (3)	2.50 (3)	3.270 (2)	132.9 (19)
Symmetry codes: (i) x+1, y, z; (ii) x-1, y, z; (iii) -x+2, -y+1, -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: 10.1107/S1600536810007397/sj2737sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536810007397/sj2737Isup2.hkl

checkCIF report

Comment top

A series of isoquinoline-1,3,4-trione derivatives were identified as novel and potent inhibitors of caspase-3 through structural modification of the original compounds from high-throughput screening (Chen et al., 2006). Moreover, the series of isoquinoline-1,3,4-triones were found to be fast-acting post-emergence herbicides, producing symptoms of desiccation (Mitchell et al., 2000). These redox-active compounds are very potent stimulators of the light-dependent consumption of oxygen at photosystem in isolated chloroplasts (Mitchell et al., 1995). Isoquinoline-1,3,4-trione derivatives have a variety of biological activities and are synthetic precursors for many naturally occuring alkaloids (Hall et al., 1994; Malamas & Hohman, 1994). The crystal structure of the related Z-2-methyl-3'-phenyl-spiro[isoquinoline-4,2'-oxirane]-1,3-dione has been reported (Wang et al., 2000).

In the title isoquinoline-1,3-dione compound (Fig. 1), the piperidine ring (C1/N1/C2/C3/C8/C9) in the 1,2,3,4-tetrahydroisoquinolin moiety adopts a half-boat conformation (Cremer & Pople, 1975) with puckering parameters of Q = 0.3114 (19) Å, θ = 71.4 (3)° and ϕ = 114.9 (4)°. The oxazole ring (C11/C12/N2/C13/O4) is essentially planar with maximum deviation of -0.004 (2) Å at atom C13. The oxazole ring is inclined at a dihedral angle of 36.00 (8)° with the mean plane through 1,2,3,4-tetrahydroisoquinolin moiety. Bond lengths (Allen et al., 1987) and angles are normal and comparable to those related isoquinoline-1,3-dione structures (Wang et al., 2000; Subbiah Pandi et al., 2002).

In the crystal structure (Fig. 2), intermolecular O3—H1O3···N2 and C16—H16A···O1 hydrogen bonds (Table 1) link the molecules into one-dimensional chains along a axis incorporating R²₂(9) ring motifs (Bernstein et al., 1995). Two neighbouring chains are further interconnected by intermolecular C16—H16B···O1 hydrogen bonds into two-molecule-wide chains along the same axis.

Related literature top

For general background to and applications of the title isoquinoline compound, see: Chen et al. (2006); Hall et al. (1994); Malamas & Hohman (1994); Mitchell et al. (1995, 2000). For ring conformations, see: Cremer & Pople (1975). For hydrogen-bond motifs, see: Bernstein et al. (1995). For related structures, see: Subbiah Pandi et al. (2002); Wang et al. (2000). For bond-length data, see: Allen et al. (1987). For the stability of the temperature controller used for the data collection, see: Cosier & Glazer (1986).

Experimental top

The title compound was obtained in the reaction between 1,3,4(2H)-isoquinolinetrione and 2,4,5-trimethyloxazole. The compound was purified by flash column chromatography in ethyl acetate and petroleum ether. X-ray quality single crystals of the title compound were obtained from slow evaporation of a chloroform solution. M.p. 434–436 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 structure of the title compound, showing the atom numbering scheme. Displacement ellipsoids are drawn at the 30% probability level.
	Fig. 2. The crystal structure of the title compound, showing two-molecule-wide chain along the a axis. H atoms not involved in intermolecular interactions (dashed lines) have been omitted for clarity.

4-[(2,4-Dimethyl-1,3-oxazol-5-yl)methyl]-4-hydroxy-2-methylisoquinoline- 1,3(2H,4H)-dione top

Crystal data top

C₁₆H₁₆N₂O₄	Z = 2
M_r = 300.31	F(000) = 316
Triclinic, P1	D_x = 1.421 Mg m⁻³
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 8.3866 (5) Å	Cell parameters from 1833 reflections
b = 8.8044 (5) Å	θ = 4.4–32.7°
c = 10.6734 (7) Å	µ = 0.10 mm⁻¹
α = 103.997 (3)°	T = 100 K
β = 90.025 (3)°	Block, colourless
γ = 112.663 (2)°	0.24 × 0.19 × 0.08 mm
V = 701.80 (7) Å³

Data collection top

Bruker SMART APEXII CCD area-detector diffractometer	3198 independent reflections
Radiation source: fine-focus sealed tube	2401 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.034
ϕ and ω scans	θ_max = 27.5°, θ_min = 2.7°
Absorption correction: multi-scan (SADABS; Bruker, 2009)	h = −10→10
T_min = 0.976, T_max = 0.992	k = −11→11
6623 measured reflections	l = −13→13

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)] = 0.050	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.135	All H-atom parameters refined
S = 1.04	w = 1/[σ²(F_o²) + (0.0731P)² + 0.0844P] where P = (F_o² + 2F_c²)/3
3198 reflections	(Δ/σ)_max < 0.001
263 parameters	Δρ_max = 0.40 e Å⁻³
0 restraints	Δρ_min = −0.28 e Å⁻³

Crystal data top

C₁₆H₁₆N₂O₄	γ = 112.663 (2)°
M_r = 300.31	V = 701.80 (7) Å³
Triclinic, P1	Z = 2
a = 8.3866 (5) Å	Mo Kα radiation
b = 8.8044 (5) Å	µ = 0.10 mm⁻¹
c = 10.6734 (7) Å	T = 100 K
α = 103.997 (3)°	0.24 × 0.19 × 0.08 mm
β = 90.025 (3)°

Data collection top

Bruker SMART APEXII CCD area-detector diffractometer	3198 independent reflections
Absorption correction: multi-scan (SADABS; Bruker, 2009)	2401 reflections with I > 2σ(I)
T_min = 0.976, T_max = 0.992	R_int = 0.034
6623 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.050	0 restraints
wR(F²) = 0.135	All H-atom parameters refined
S = 1.04	Δρ_max = 0.40 e Å⁻³
3198 reflections	Δρ_min = −0.28 e Å⁻³
263 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	1.23014 (16)	0.40877 (16)	0.32581 (13)	0.0234 (3)
O2	0.76462 (17)	0.27268 (17)	0.04028 (14)	0.0269 (3)
O3	1.13932 (17)	0.07862 (17)	0.33591 (13)	0.0224 (3)
O4	0.78937 (15)	0.36205 (15)	0.40053 (12)	0.0185 (3)
N1	0.99911 (18)	0.34315 (18)	0.18332 (15)	0.0175 (3)
N2	0.50707 (18)	0.22071 (19)	0.33559 (15)	0.0186 (3)
C1	1.0928 (2)	0.3023 (2)	0.26656 (17)	0.0175 (4)
C2	0.8503 (2)	0.2243 (2)	0.10092 (18)	0.0187 (4)
C3	0.8116 (2)	0.0419 (2)	0.08846 (17)	0.0175 (4)
C4	0.6900 (2)	−0.0817 (2)	−0.01212 (19)	0.0217 (4)
C5	0.6559 (2)	−0.2517 (3)	−0.0275 (2)	0.0249 (4)
C6	0.7436 (3)	−0.3003 (2)	0.0555 (2)	0.0249 (4)
C7	0.8637 (2)	−0.1782 (2)	0.15593 (19)	0.0209 (4)
C8	0.8972 (2)	−0.0063 (2)	0.17380 (17)	0.0171 (4)
C9	1.0118 (2)	0.1260 (2)	0.29105 (18)	0.0175 (4)
C10	0.8979 (2)	0.1419 (3)	0.40732 (18)	0.0191 (4)
C11	0.7513 (2)	0.1891 (2)	0.38373 (17)	0.0172 (4)
C12	0.5796 (2)	0.1033 (2)	0.34423 (17)	0.0180 (4)
C13	0.6360 (2)	0.3692 (2)	0.36869 (17)	0.0179 (4)
C14	1.0594 (3)	0.5246 (2)	0.1865 (2)	0.0238 (4)
C15	0.4717 (3)	−0.0836 (2)	0.3101 (2)	0.0238 (4)
C16	0.6387 (2)	0.5395 (2)	0.3724 (2)	0.0216 (4)
H1O3	1.243 (4)	0.142 (3)	0.321 (3)	0.054 (8)*
H4A	0.637 (3)	−0.043 (3)	−0.065 (2)	0.033 (6)*
H5A	0.574 (3)	−0.336 (3)	−0.097 (2)	0.031 (6)*
H6A	0.722 (3)	−0.420 (3)	0.045 (2)	0.029 (6)*
H7A	0.924 (3)	−0.208 (2)	0.217 (2)	0.019 (5)*
H10A	0.855 (3)	0.032 (3)	0.430 (2)	0.024 (5)*
H10B	0.979 (3)	0.226 (3)	0.484 (2)	0.024 (5)*
H14A	1.064 (3)	0.595 (3)	0.277 (3)	0.045 (7)*
H14B	0.985 (3)	0.538 (3)	0.127 (3)	0.048 (7)*
H14C	1.175 (4)	0.565 (3)	0.154 (3)	0.052 (8)*
H15A	0.436 (3)	−0.124 (3)	0.215 (3)	0.037 (6)*
H15B	0.530 (3)	−0.148 (3)	0.337 (2)	0.040 (7)*
H15C	0.360 (3)	−0.114 (3)	0.349 (3)	0.047 (7)*
H16A	0.526 (3)	0.529 (3)	0.344 (2)	0.037 (6)*
H16B	0.682 (3)	0.622 (3)	0.461 (3)	0.039 (6)*
H16C	0.718 (4)	0.594 (3)	0.314 (3)	0.053 (8)*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1	0.0134 (6)	0.0238 (7)	0.0300 (8)	0.0053 (5)	−0.0010 (5)	0.0053 (6)
O2	0.0215 (7)	0.0300 (8)	0.0333 (8)	0.0113 (6)	−0.0025 (6)	0.0136 (6)
O3	0.0105 (6)	0.0283 (7)	0.0340 (8)	0.0096 (6)	0.0033 (5)	0.0151 (6)
O4	0.0104 (6)	0.0223 (7)	0.0219 (7)	0.0072 (5)	0.0009 (5)	0.0026 (5)
N1	0.0133 (7)	0.0185 (7)	0.0224 (8)	0.0073 (6)	0.0023 (6)	0.0070 (6)
N2	0.0116 (7)	0.0221 (8)	0.0226 (8)	0.0077 (6)	0.0020 (6)	0.0052 (6)
C1	0.0132 (8)	0.0217 (9)	0.0203 (9)	0.0095 (7)	0.0049 (7)	0.0063 (7)
C2	0.0126 (8)	0.0260 (9)	0.0204 (9)	0.0092 (7)	0.0053 (7)	0.0088 (7)
C3	0.0113 (8)	0.0210 (9)	0.0203 (9)	0.0062 (7)	0.0045 (7)	0.0057 (7)
C4	0.0157 (9)	0.0290 (10)	0.0205 (9)	0.0086 (8)	0.0036 (7)	0.0073 (8)
C5	0.0167 (9)	0.0267 (10)	0.0240 (10)	0.0045 (8)	0.0035 (8)	0.0004 (8)
C6	0.0225 (10)	0.0201 (10)	0.0315 (11)	0.0087 (8)	0.0095 (8)	0.0055 (8)
C7	0.0167 (9)	0.0220 (9)	0.0271 (10)	0.0098 (8)	0.0055 (7)	0.0086 (8)
C8	0.0115 (8)	0.0212 (9)	0.0203 (9)	0.0075 (7)	0.0058 (7)	0.0070 (7)
C9	0.0112 (8)	0.0249 (9)	0.0210 (9)	0.0102 (7)	0.0026 (7)	0.0090 (7)
C10	0.0122 (8)	0.0270 (10)	0.0199 (9)	0.0086 (7)	0.0022 (7)	0.0079 (8)
C11	0.0133 (8)	0.0224 (9)	0.0162 (9)	0.0075 (7)	0.0033 (7)	0.0047 (7)
C12	0.0143 (8)	0.0236 (9)	0.0174 (9)	0.0087 (7)	0.0025 (7)	0.0055 (7)
C13	0.0108 (8)	0.0256 (10)	0.0169 (9)	0.0080 (7)	0.0009 (6)	0.0036 (7)
C14	0.0230 (10)	0.0190 (9)	0.0302 (11)	0.0084 (8)	0.0015 (8)	0.0077 (8)
C15	0.0157 (9)	0.0219 (10)	0.0333 (12)	0.0055 (8)	0.0027 (8)	0.0099 (8)
C16	0.0139 (9)	0.0216 (9)	0.0285 (11)	0.0067 (7)	0.0011 (8)	0.0059 (8)

Geometric parameters (Å, º) top

O1—C1	1.219 (2)	C6—H6A	0.98 (2)
O2—C2	1.219 (2)	C7—C8	1.392 (2)
O3—C9	1.4096 (19)	C7—H7A	0.97 (2)
O3—H1O3	0.87 (3)	C8—C9	1.510 (2)
O4—C13	1.3590 (19)	C9—C10	1.579 (3)
O4—C11	1.395 (2)	C10—C11	1.481 (2)
N1—C1	1.381 (2)	C10—H10A	0.99 (2)
N1—C2	1.405 (2)	C10—H10B	1.00 (2)
N1—C14	1.469 (2)	C11—C12	1.352 (2)
N2—C13	1.300 (2)	C12—C15	1.491 (3)
N2—C12	1.407 (2)	C13—C16	1.481 (3)
C1—C9	1.524 (2)	C14—H14A	1.01 (3)
C2—C3	1.482 (2)	C14—H14B	0.94 (3)
C3—C8	1.395 (2)	C14—H14C	0.99 (3)
C3—C4	1.398 (3)	C15—H15A	1.00 (3)
C4—C5	1.379 (3)	C15—H15B	0.97 (2)
C4—H4A	0.91 (2)	C15—H15C	0.99 (3)
C5—C6	1.391 (3)	C16—H16A	0.95 (2)
C5—H5A	0.96 (2)	C16—H16B	1.01 (3)
C6—C7	1.388 (3)	C16—H16C	0.98 (3)

C9—O3—H1O3	111.7 (18)	C1—C9—C10	106.39 (14)
C13—O4—C11	105.09 (13)	C11—C10—C9	115.98 (15)
C1—N1—C2	124.28 (14)	C11—C10—H10A	110.1 (12)
C1—N1—C14	116.33 (15)	C9—C10—H10A	106.9 (13)
C2—N1—C14	119.36 (14)	C11—C10—H10B	111.0 (12)
C13—N2—C12	105.17 (14)	C9—C10—H10B	106.8 (12)
O1—C1—N1	120.67 (16)	H10A—C10—H10B	105.3 (17)
O1—C1—C9	121.09 (15)	C12—C11—O4	107.30 (14)
N1—C1—C9	118.01 (15)	C12—C11—C10	135.61 (17)
O2—C2—N1	120.21 (16)	O4—C11—C10	117.05 (15)
O2—C2—C3	123.36 (17)	C11—C12—N2	108.95 (15)
N1—C2—C3	116.36 (14)	C11—C12—C15	129.76 (17)
C8—C3—C4	120.28 (16)	N2—C12—C15	121.29 (15)
C8—C3—C2	120.80 (16)	N2—C13—O4	113.49 (15)
C4—C3—C2	118.91 (16)	N2—C13—C16	129.41 (16)
C5—C4—C3	119.75 (18)	O4—C13—C16	117.08 (15)
C5—C4—H4A	123.9 (14)	N1—C14—H14A	110.5 (14)
C3—C4—H4A	116.4 (14)	N1—C14—H14B	109.2 (15)
C4—C5—C6	120.24 (18)	H14A—C14—H14B	112 (2)
C4—C5—H5A	119.7 (13)	N1—C14—H14C	110.9 (15)
C6—C5—H5A	120.0 (13)	H14A—C14—H14C	110 (2)
C7—C6—C5	120.25 (18)	H14B—C14—H14C	104 (2)
C7—C6—H6A	118.6 (13)	C12—C15—H15A	108.7 (13)
C5—C6—H6A	121.1 (13)	C12—C15—H15B	112.9 (14)
C6—C7—C8	120.05 (18)	H15A—C15—H15B	111 (2)
C6—C7—H7A	122.2 (12)	C12—C15—H15C	113.7 (15)
C8—C7—H7A	117.7 (12)	H15A—C15—H15C	104 (2)
C7—C8—C3	119.42 (17)	H15B—C15—H15C	106 (2)
C7—C8—C9	120.71 (16)	C13—C16—H16A	110.0 (14)
C3—C8—C9	119.63 (15)	C13—C16—H16B	112.3 (13)
O3—C9—C8	112.25 (14)	H16A—C16—H16B	111 (2)
O3—C9—C1	111.38 (14)	C13—C16—H16C	112.0 (16)
C8—C9—C1	111.91 (14)	H16A—C16—H16C	106 (2)
O3—C9—C10	105.32 (14)	H16B—C16—H16C	105 (2)
C8—C9—C10	109.17 (14)

C2—N1—C1—O1	172.69 (16)	C3—C8—C9—C1	−29.7 (2)
C14—N1—C1—O1	−9.2 (3)	C7—C8—C9—C10	−86.56 (19)
C2—N1—C1—C9	−12.7 (2)	C3—C8—C9—C10	87.76 (19)
C14—N1—C1—C9	165.40 (16)	O1—C1—C9—O3	−27.0 (2)
C1—N1—C2—O2	172.40 (17)	N1—C1—C9—O3	158.35 (15)
C14—N1—C2—O2	−5.6 (3)	O1—C1—C9—C8	−153.60 (16)
C1—N1—C2—C3	−10.5 (2)	N1—C1—C9—C8	31.8 (2)
C14—N1—C2—C3	171.54 (16)	O1—C1—C9—C10	87.24 (19)
O2—C2—C3—C8	−170.30 (17)	N1—C1—C9—C10	−87.39 (18)
N1—C2—C3—C8	12.7 (2)	O3—C9—C10—C11	−179.26 (15)
O2—C2—C3—C4	11.0 (3)	C8—C9—C10—C11	−58.5 (2)
N1—C2—C3—C4	−166.05 (16)	C1—C9—C10—C11	62.40 (19)
C8—C3—C4—C5	−0.6 (3)	C13—O4—C11—C12	−0.42 (18)
C2—C3—C4—C5	178.13 (17)	C13—O4—C11—C10	177.85 (15)
C3—C4—C5—C6	−0.8 (3)	C9—C10—C11—C12	95.1 (3)
C4—C5—C6—C7	1.1 (3)	C9—C10—C11—O4	−82.6 (2)
C5—C6—C7—C8	−0.1 (3)	O4—C11—C12—N2	0.00 (19)
C6—C7—C8—C3	−1.3 (3)	C10—C11—C12—N2	−177.81 (19)
C6—C7—C8—C9	173.05 (17)	O4—C11—C12—C15	178.81 (18)
C4—C3—C8—C7	1.6 (3)	C10—C11—C12—C15	1.0 (4)
C2—C3—C8—C7	−177.07 (16)	C13—N2—C12—C11	0.4 (2)
C4—C3—C8—C9	−172.78 (16)	C13—N2—C12—C15	−178.48 (17)
C2—C3—C8—C9	8.5 (3)	C12—N2—C13—O4	−0.7 (2)
C7—C8—C9—O3	29.8 (2)	C12—N2—C13—C16	177.28 (19)
C3—C8—C9—O3	−155.84 (15)	C11—O4—C13—N2	0.75 (19)
C7—C8—C9—C1	155.93 (16)	C11—O4—C13—C16	−177.54 (16)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O3—H1O3···N2ⁱ	0.87 (3)	2.04 (3)	2.847 (2)	153 (3)
C16—H16A···O1ⁱⁱ	0.96 (3)	2.28 (3)	3.162 (2)	153 (2)
C16—H16B···O1ⁱⁱⁱ	1.01 (3)	2.50 (3)	3.270 (2)	132.9 (19)

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

Experimental details

Crystal data
Chemical formula	C₁₆H₁₆N₂O₄
M_r	300.31
Crystal system, space group	Triclinic, P1
Temperature (K)	100
a, b, c (Å)	8.3866 (5), 8.8044 (5), 10.6734 (7)
α, β, γ (°)	103.997 (3), 90.025 (3), 112.663 (2)
V (Å³)	701.80 (7)
Z	2
Radiation type	Mo Kα
µ (mm⁻¹)	0.10
Crystal size (mm)	0.24 × 0.19 × 0.08

Data collection
Diffractometer	Bruker SMART APEXII CCD area-detector diffractometer
Absorption correction	Multi-scan (SADABS; Bruker, 2009)
T_min, T_max	0.976, 0.992
No. of measured, independent and observed [I > 2σ(I)] reflections	6623, 3198, 2401
R_int	0.034
(sin θ/λ)_max (Å⁻¹)	0.650

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.050, 0.135, 1.04
No. of reflections	3198
No. of parameters	263
H-atom treatment	All H-atom parameters refined
Δρ_max, Δρ_min (e Å⁻³)	0.40, −0.28

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
O3—H1O3···N2ⁱ	0.87 (3)	2.04 (3)	2.847 (2)	153 (3)
C16—H16A···O1ⁱⁱ	0.96 (3)	2.28 (3)	3.162 (2)	153 (2)
C16—H16B···O1ⁱⁱⁱ	1.01 (3)	2.50 (3)	3.270 (2)	132.9 (19)

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

Footnotes

‡Thomson Reuters ResearcherID: A-3561-2009.

§Thomson Reuters ResearcherID: C-7576-2009.

Acknowledgements

Financial support from the Ministry of Science and Technology of China of the Austria–China Cooperation project (2007DFA41590) is acknowledged. HKF and JHG thank Universiti Sains Malaysia (USM) for the Research University Golden Goose grant (No. 1001/PFIZIK/811012). JHG also thanks USM for the award of a USM fellowship.

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