A 3,5-dinitro­benzoyl derivative of a stereoisomer of glycerol menthonide

Kiessling, A.; Campana, C.; Kastner, M.E.

doi:10.1107/S1600536809020960

organic compounds

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ISSN: 2056-9890

Volume 65| Part 7| July 2009| Page o1540

doi:10.1107/S1600536809020960

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A 3,5-dinitrobenzoyl derivative of a stereoisomer of glycerol menthonide

Anthony Kiessling,^a ^* Charles Campana ^b and Margaret E. Kastner ^c

^aDepartment of Chemistry and Physics, Mansfield University, Mansfield, PA 16933, USA, ^bSenior Scientist, Single CrystalDiffraction, Bruker AXS Inc., 5465 East Cheryl Parkway, Madison, WI 53711-5373, USA, and ^cDepartment of Chemistry, Bucknell University, Lewisburg, PA 17837, USA
^*Correspondence e-mail: akiessli@mansfield.edu

(Received 19 May 2009; accepted 3 June 2009; online 10 June 2009)

The title compound, [(2S,5R,6S,9R)-6-isopropyl-9-methyl-1,4-dioxaspiro[4.5]dec-2-yl]methyl 3,5-dinitrobenzoate, C₂₀H₂₆N₂O₈, was synthesized as part of a study of three-carbon stereochemical systems. The crystallographic assignment of the absolute stereochemistry is consistent with having started with (−)-menthone, the acetal carbon is R and the secondary alcohol is S. This brings the dinitrobenzoate into approximately the same plane as the menthyl ring and anti to the isopropyl group. Close intermolecular C=O⋯NO₂ contacts between neighboring molecules [2.8341 (16) Å] contribute to the packing arrangement. The structure was refined as a pseudo-merohedral twin (monoclinic space group P2₁ emulating the orthorhombic space group C222₁). Application of the twin law 100, 0 $[\overline{1}]$ 0, $[\overline{1}]$ 0 $[\overline{1}]$ gave a 2:1 ratio of twin moieties [refined BASF value = 0.3790 (7)].

Related literature

For the synthesis of glycerol menthonide, see: Greenberg (1999 ). For the synthesis and NMR spectra of the title compound, see: Kiessling et al. (2009 ). Glidewell et al. (2003 ) report a related structure with a very short C=O ⋯ NO₂ distance. Allen et al. (1998 ) discuss intermolecular C=O ⋯ C=O interactions. For a description of the Cambridge Crystallographic Database, see: Allen (2002 ).

Experimental

Crystal data

C₂₀H₂₆N₂O₈
M_r = 422.43
Monoclinic, P 2₁
a = 9.4396 (5) Å
b = 5.8825 (3) Å
c = 19.6719 (10) Å
β = 103.923 (3)°
V = 1060.26 (9) Å³
Z = 2
Cu Kα radiation
μ = 0.87 mm⁻¹
T = 100 K
0.38 × 0.09 × 0.02 mm

Data collection

Bruker SMART APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2008 ) T_min = 0.602, T_max = 0.977
16481 measured reflections
3275 independent reflections
3254 reflections with I > 2σ(I)
R_int = 0.025

Refinement

R[F² > 2σ(F²)] = 0.018
wR(F²) = 0.045
S = 1.06
3275 reflections
276 parameters
1 restraint
H-atom parameters constrained
Δρ_max = 0.10 e Å⁻³
Δρ_min = −0.11 e Å⁻³
Absolute structure: Flack (1983 ), 1131 Friedel pairs
Flack parameter: 0.03 (13)

Data collection: APEX2 (Bruker, 2008); cell refinement: SAINT (Bruker, 2008); 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.

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536809020960/zl2211sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536809020960/zl2211Isup2.hkl

checkCIF report

Comment top

The title structure was synthesized as part of a study of 3-carbon stereochemical moieties, specifically tri-substituted glycerol. Here menthone serves as a chiral auxiliary, freezing two carbons into a specific stereochemistry and influencing the stereochemistry of the third owing to the steric bulk of the menthone.

The starting material, glycerol menthonide, was originally prepared as an additive to spearmint gum by reaction of menthone with glycerol under acid catalysis. (Greenberg, 1999) No further chemical analysis of the menthonide has been reported in the literature.

Glycerol menthonide exists in as many as six isomers which are difficult to separate. However, conversion of the hydroxy group to an ester by reaction with 4-bromobenzoyl chloride yields a mixture of esters that are separable by flash chromatography.

One stereochemically pure ester was hydrolyzed back to the free alcohol then converted to the 3,5-dinitrobenzoate. The crystallographic assignment of the absolute stereochemistry is consistent with having started with (-)-menthone, and provides the stereochemistry of the acetal carbon and the esterified secondary alcohol of the glycerol chain. Specifically, the acetal carbon, C5, is R and the secondary alcohol, C2, is S. This brings the dinitrobenzoate into approximately the same plane as the menthyl ring and anti to the isopropyl group.

There is a close contact between the carbonyl oxygen, O25, and one of the nitro groups on a 2₁ screw-related molecule, specifically N28 in the molecule at (1 - x, -0.5, 2 - z). The orientation of the carbonyl group is nearly perpendicular to the plane of the nitro group and the O25 ··· N28 distance is 2.8341 (16) Å. A search of the Cambridge Structural Database (Allen, 2002) for intermolecular C=O ··· NO₂-benzene groups found 360 observations for C=O ··· NO₂ distances of 3.07 or less. Of these, only seventeen observations were shorter than that reported here, and each of these had a similar perpendicular orientation. The simplest structure in this set is that of 3-nitrophthalic acid (Glidewell et al., 2003) wherein the C=O ··· NO₂ distance was reported as 2.807 (2) Å, which the authors attributed to the electrostatic interaction between the partially negative oxygen of the carbonyl and the partially positive nitrogen of the nitro group and analogous to the short intermolecular C=O ··· C=O contacts frequently found between carbonyl groups.

In a study (Allen, et al., 1998) of these intermolecular C=O ··· C=O interactions based on a combination of a detailed analysis of structures from the Cambridge Structural Database as well as ab initio molecular-orbital calculations the authors conclude that, although these intermolecular forces are only a fraction of that of hydrogen bonds, they are significant contributors to the stabilization of the solid state structures. It appears a similar argument could be made for C=O ··· NO₂ interactions.

Related literature top

For the synthesis of glycerol menthonide, see: Greenberg (1999). For the synthesis and NMR spectra of the title compound, see: Kiessling et al. (2009). Glidewell et al. (2003) report a releted structure with a very short C=O ··· NO₂ distance. Allen et al. (1998) report on intermolecular C=O ··· C=O interactions. For a description of the Cambridge Crystallographic Database, see: Allen (2002).

Experimental top

Details on the synthesis of the title compound and its NMR spectra have been published separately. (Kiessling et al., 2009)

Computing details top

Data collection: APEX2 (Bruker, 2008); cell refinement: SAINT (Bruker, 2008); data reduction: SAINT (Bruker, 2008); 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).

Figures top

	Fig. 1. The title compound, C₂₀H₂₆N₂O₈, showing 50% probability displacement ellipsoids and the atom-numbering scheme.
	Fig. 2. A packing diagram of the title compound. The close intermolecular C═O···NO₂ contact is shown by the dotted lines.

[(2S,5R,6S,9R)-6-isopropyl-9-methyl-1,4- dioxaspiro[4.5]dec-2-yl]methyl 3,5-dinitrobenzoate top

Crystal data top

C₂₀H₂₆N₂O₈	F(000) = 448
M_r = 422.43	D_x = 1.323 Mg m⁻³
Monoclinic, P2₁	Melting point: 368 K
Hall symbol: P 2yb	Cu Kα radiation, λ = 1.54178 Å
a = 9.4396 (5) Å	Cell parameters from 9947 reflections
b = 5.8825 (3) Å	θ = 2.3–68.2°
c = 19.6719 (10) Å	µ = 0.87 mm⁻¹
β = 103.923 (3)°	T = 100 K
V = 1060.26 (9) Å³	Needle, colourless
Z = 2	0.38 × 0.09 × 0.02 mm

Data collection top

Bruker SMART APEXII CCD area-detector diffractometer	3275 independent reflections
Radiation source: fine-focus sealed tube	3254 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.025
ϕ and ω scans	θ_max = 68.2°, θ_min = 2.3°
Absorption correction: multi-scan (SADABS; Bruker, 2008)	h = −11→11
T_min = 0.602, T_max = 0.977	k = −6→5
16481 measured reflections	l = −23→23

Refinement top

Refinement on F²	Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: full	H-atom parameters constrained
R[F² > 2σ(F²)] = 0.018	w = 1/[σ²(F_o²) + (0.0245P)² + 0.0832P] where P = (F_o² + 2F_c²)/3
wR(F²) = 0.045	(Δ/σ)_max = 0.001
S = 1.06	Δρ_max = 0.10 e Å⁻³
3275 reflections	Δρ_min = −0.11 e Å⁻³
276 parameters	Extinction correction: SHELXTL (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc²λ³/sin(2θ)]^-1/4
1 restraint	Extinction coefficient: 0.0009 (2)
Primary atom site location: structure-invariant direct methods	Absolute structure: Flack (1983), 1131 Friedel pairs
Secondary atom site location: difference Fourier map	Absolute structure parameter: 0.03 (13)

Crystal data top

C₂₀H₂₆N₂O₈	V = 1060.26 (9) Å³
M_r = 422.43	Z = 2
Monoclinic, P2₁	Cu Kα radiation
a = 9.4396 (5) Å	µ = 0.87 mm⁻¹
b = 5.8825 (3) Å	T = 100 K
c = 19.6719 (10) Å	0.38 × 0.09 × 0.02 mm
β = 103.923 (3)°

Data collection top

Bruker SMART APEXII CCD area-detector diffractometer	3275 independent reflections
Absorption correction: multi-scan (SADABS; Bruker, 2008)	3254 reflections with I > 2σ(I)
T_min = 0.602, T_max = 0.977	R_int = 0.025
16481 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.018	H-atom parameters constrained
wR(F²) = 0.045	Δρ_max = 0.10 e Å⁻³
S = 1.06	Δρ_min = −0.11 e Å⁻³
3275 reflections	Absolute structure: Flack (1983), 1131 Friedel pairs
276 parameters	Absolute structure parameter: 0.03 (13)
1 restraint

Special details top

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'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. The structure was refined as a pseudo-merohedral twin (monoclinic space group P2₁ emulating orthorhombic space group C222₁); Twin law 1 0 0 0 - 1 0 - 1 0 - 1; Refined ratio (BASF) 0.3790 (7).

Hydrogen positions were calculated and refined using a riding model using the following C—H distances: methyne 1.000 Å, methylene 0.990 Å, methyl 0.980Å and aromatic 0.950 Å. The isotropic U values for the H atoms were set at 50% above that of bonded carbon for methyl H atoms and 20% above that of the bonded carbon for all other H atoms.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
O1	0.72662 (12)	−0.12929 (19)	0.71101 (5)	0.0258 (3)
C2	0.81610 (17)	−0.1291 (3)	0.78046 (7)	0.0227 (3)
H2	0.9171	−0.1783	0.7796	0.027*
C3	0.81810 (17)	0.1200 (3)	0.80073 (8)	0.0222 (3)
H3A	0.7329	0.1589	0.8196	0.027*
H3B	0.9088	0.1591	0.8359	0.027*
O4	0.81137 (12)	0.23300 (19)	0.73591 (5)	0.0227 (2)
C5	0.72348 (19)	0.0946 (3)	0.68212 (8)	0.0232 (3)
C6	0.78923 (18)	0.0943 (3)	0.61799 (8)	0.0266 (4)
H6	0.7245	−0.0053	0.5824	0.032*
C7	0.7763 (2)	0.3330 (3)	0.58613 (8)	0.0329 (4)
H7A	0.8359	0.4400	0.6202	0.039*
H7B	0.8154	0.3319	0.5437	0.039*
C8	0.6194 (2)	0.4149 (4)	0.56676 (8)	0.0365 (4)
H8A	0.5619	0.3166	0.5293	0.044*
H8B	0.6163	0.5717	0.5482	0.044*
C9	0.54978 (19)	0.4117 (3)	0.62943 (8)	0.0308 (4)
H9	0.6041	0.5223	0.6649	0.037*
C10	0.56642 (18)	0.1768 (3)	0.66303 (8)	0.0270 (4)
H10A	0.5289	0.1811	0.7059	0.032*
H10B	0.5063	0.0670	0.6302	0.032*
C11	0.3900 (2)	0.4850 (4)	0.60923 (11)	0.0461 (5)
H11A	0.3347	0.3813	0.5736	0.069*
H11B	0.3831	0.6400	0.5904	0.069*
H11C	0.3497	0.4809	0.6507	0.069*
C12	0.9428 (2)	−0.0117 (4)	0.63175 (9)	0.0344 (4)
H12	0.9459	−0.1414	0.6649	0.041*
C13	0.9717 (2)	−0.1084 (4)	0.56378 (9)	0.0400 (5)
H13A	0.9693	0.0152	0.5301	0.060*
H13B	0.8964	−0.2206	0.5439	0.060*
H13C	1.0678	−0.1814	0.5740	0.060*
C14	1.0663 (2)	0.1510 (5)	0.66460 (13)	0.0633 (8)
H14A	1.1582	0.0664	0.6782	0.095*
H14B	1.0452	0.2222	0.7061	0.095*
H14C	1.0748	0.2687	0.6306	0.095*
C15	0.75391 (17)	−0.2914 (3)	0.82456 (8)	0.0241 (3)
H15A	0.7341	−0.4403	0.8007	0.029*
H15B	0.8241	−0.3148	0.8703	0.029*
O16	0.61928 (12)	−0.19409 (19)	0.83493 (5)	0.0219 (3)
C17	0.55649 (16)	−0.3039 (3)	0.87874 (7)	0.0204 (3)
C18	0.43170 (16)	−0.1728 (3)	0.89389 (7)	0.0195 (3)
C19	0.36462 (15)	−0.2611 (3)	0.94374 (7)	0.0207 (3)
H19	0.3984	−0.3989	0.9673	0.025*
C20	0.24814 (16)	−0.1456 (3)	0.95844 (7)	0.0196 (3)
C21	0.19642 (16)	0.0567 (3)	0.92634 (7)	0.0197 (3)
H21	0.1167	0.1350	0.9373	0.024*
C22	0.26696 (16)	0.1397 (3)	0.87730 (8)	0.0203 (3)
C23	0.38314 (16)	0.0311 (3)	0.86020 (8)	0.0196 (3)
H23	0.4288	0.0936	0.8264	0.024*
O24	0.59532 (12)	−0.4860 (2)	0.90476 (6)	0.0267 (3)
N25	0.21586 (14)	0.3563 (2)	0.84164 (6)	0.0219 (3)
O26	0.28039 (12)	0.4291 (2)	0.79908 (5)	0.0270 (3)
O27	0.11232 (11)	0.4517 (2)	0.85721 (6)	0.0275 (3)
N28	0.17654 (13)	−0.2454 (3)	1.01017 (6)	0.0222 (3)
O29	0.07569 (12)	−0.1400 (2)	1.02463 (6)	0.0299 (3)
O30	0.22049 (12)	−0.4300 (2)	1.03556 (6)	0.0271 (3)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1	0.0394 (6)	0.0178 (6)	0.0215 (5)	−0.0057 (5)	0.0101 (5)	−0.0007 (4)
C2	0.0236 (7)	0.0238 (9)	0.0229 (7)	0.0038 (7)	0.0097 (6)	0.0018 (7)
C3	0.0224 (7)	0.0251 (10)	0.0197 (7)	−0.0025 (7)	0.0061 (6)	−0.0017 (7)
O4	0.0302 (5)	0.0196 (6)	0.0189 (5)	−0.0046 (5)	0.0068 (4)	−0.0012 (5)
C5	0.0325 (8)	0.0158 (9)	0.0218 (7)	−0.0054 (7)	0.0075 (7)	−0.0010 (6)
C6	0.0348 (9)	0.0263 (10)	0.0196 (7)	−0.0092 (8)	0.0083 (7)	−0.0040 (7)
C7	0.0457 (11)	0.0308 (11)	0.0237 (7)	−0.0144 (8)	0.0114 (7)	0.0002 (8)
C8	0.0484 (11)	0.0313 (11)	0.0249 (8)	−0.0089 (9)	−0.0011 (7)	0.0060 (7)
C9	0.0340 (9)	0.0238 (11)	0.0299 (8)	−0.0050 (8)	−0.0013 (7)	0.0004 (7)
C10	0.0279 (8)	0.0261 (10)	0.0266 (7)	−0.0081 (7)	0.0057 (6)	−0.0018 (7)
C11	0.0405 (11)	0.0406 (14)	0.0503 (11)	0.0012 (10)	−0.0023 (9)	0.0048 (10)
C12	0.0388 (10)	0.0405 (12)	0.0272 (8)	−0.0038 (9)	0.0144 (8)	−0.0053 (8)
C13	0.0560 (12)	0.0388 (12)	0.0327 (8)	−0.0020 (10)	0.0253 (9)	0.0000 (8)
C14	0.0360 (11)	0.093 (2)	0.0638 (13)	−0.0085 (12)	0.0177 (10)	−0.0370 (15)
C15	0.0248 (8)	0.0232 (10)	0.0266 (7)	0.0072 (7)	0.0110 (6)	0.0023 (7)
O16	0.0232 (5)	0.0213 (7)	0.0236 (5)	0.0020 (4)	0.0102 (4)	0.0035 (5)
C17	0.0229 (7)	0.0205 (9)	0.0169 (6)	−0.0020 (6)	0.0034 (6)	−0.0026 (6)
C18	0.0196 (7)	0.0211 (9)	0.0172 (6)	−0.0025 (6)	0.0031 (6)	−0.0007 (6)
C19	0.0204 (8)	0.0217 (9)	0.0181 (6)	−0.0002 (7)	0.0007 (6)	0.0010 (6)
C20	0.0200 (7)	0.0222 (9)	0.0163 (6)	−0.0051 (7)	0.0036 (5)	−0.0024 (6)
C21	0.0162 (7)	0.0218 (9)	0.0208 (7)	−0.0004 (6)	0.0037 (5)	−0.0041 (6)
C22	0.0203 (7)	0.0193 (9)	0.0198 (6)	−0.0037 (6)	0.0019 (6)	−0.0015 (6)
C23	0.0206 (7)	0.0202 (9)	0.0184 (7)	−0.0032 (6)	0.0052 (6)	−0.0010 (6)
O24	0.0283 (6)	0.0241 (7)	0.0291 (5)	0.0049 (5)	0.0100 (5)	0.0089 (5)
N25	0.0209 (6)	0.0193 (8)	0.0236 (6)	−0.0027 (6)	0.0017 (5)	−0.0011 (6)
O26	0.0296 (6)	0.0245 (7)	0.0277 (5)	−0.0002 (5)	0.0083 (5)	0.0060 (5)
O27	0.0217 (5)	0.0223 (7)	0.0379 (6)	0.0024 (5)	0.0060 (5)	0.0005 (5)
N28	0.0194 (6)	0.0283 (9)	0.0186 (6)	−0.0040 (6)	0.0043 (5)	−0.0008 (6)
O29	0.0245 (6)	0.0357 (7)	0.0328 (5)	0.0008 (6)	0.0137 (5)	0.0043 (6)
O30	0.0278 (6)	0.0276 (7)	0.0263 (5)	−0.0007 (5)	0.0074 (5)	0.0068 (5)

Geometric parameters (Å, º) top

O1—C2	1.4230 (17)	C12—C13	1.537 (2)
O1—C5	1.432 (2)	C12—H12	1.0000
C2—C15	1.501 (2)	C13—H13A	0.9800
C2—C3	1.518 (2)	C13—H13B	0.9800
C2—H2	1.0000	C13—H13C	0.9800
C3—O4	1.4259 (18)	C14—H14A	0.9800
C3—H3A	0.9900	C14—H14B	0.9800
C3—H3B	0.9900	C14—H14C	0.9800
O4—C5	1.4310 (19)	C15—O16	1.4523 (18)
C5—C10	1.518 (2)	C15—H15A	0.9900
C5—C6	1.534 (2)	C15—H15B	0.9900
C6—C7	1.531 (3)	O16—C17	1.3257 (19)
C6—C12	1.541 (2)	C17—O24	1.206 (2)
C6—H6	1.0000	C17—C18	1.497 (2)
C7—C8	1.517 (3)	C18—C19	1.390 (2)
C7—H7A	0.9900	C18—C23	1.393 (2)
C7—H7B	0.9900	C19—C20	1.381 (2)
C8—C9	1.530 (2)	C19—H19	0.9500
C8—H8A	0.9900	C20—C21	1.380 (2)
C8—H8B	0.9900	C20—N28	1.4726 (19)
C9—C10	1.523 (3)	C21—C22	1.386 (2)
C9—C11	1.526 (3)	C21—H21	0.9500
C9—H9	1.0000	C22—C23	1.379 (2)
C10—H10A	0.9900	C22—N25	1.478 (2)
C10—H10B	0.9900	C23—H23	0.9500
C11—H11A	0.9800	N25—O26	1.2253 (17)
C11—H11B	0.9800	N25—O27	1.2280 (17)
C11—H11C	0.9800	N28—O30	1.2254 (18)
C12—C14	1.526 (3)	N28—O29	1.2256 (18)

C2—O1—C5	109.35 (12)	H11A—C11—H11C	109.5
O1—C2—C15	109.28 (13)	H11B—C11—H11C	109.5
O1—C2—C3	102.70 (13)	C14—C12—C13	108.84 (16)
C15—C2—C3	116.37 (13)	C14—C12—C6	114.26 (18)
O1—C2—H2	109.4	C13—C12—C6	110.70 (15)
C15—C2—H2	109.4	C14—C12—H12	107.6
C3—C2—H2	109.4	C13—C12—H12	107.6
O4—C3—C2	102.72 (12)	C6—C12—H12	107.6
O4—C3—H3A	111.2	C12—C13—H13A	109.5
C2—C3—H3A	111.2	C12—C13—H13B	109.5
O4—C3—H3B	111.2	H13A—C13—H13B	109.5
C2—C3—H3B	111.2	C12—C13—H13C	109.5
H3A—C3—H3B	109.1	H13A—C13—H13C	109.5
C3—O4—C5	106.81 (11)	H13B—C13—H13C	109.5
O4—C5—O1	106.07 (11)	C12—C14—H14A	109.5
O4—C5—C10	111.08 (13)	C12—C14—H14B	109.5
O1—C5—C10	108.47 (14)	H14A—C14—H14B	109.5
O4—C5—C6	109.35 (13)	C12—C14—H14C	109.5
O1—C5—C6	110.57 (14)	H14A—C14—H14C	109.5
C10—C5—C6	111.17 (13)	H14B—C14—H14C	109.5
C7—C6—C5	109.12 (14)	O16—C15—C2	107.91 (13)
C7—C6—C12	114.98 (15)	O16—C15—H15A	110.1
C5—C6—C12	113.93 (14)	C2—C15—H15A	110.1
C7—C6—H6	106.0	O16—C15—H15B	110.1
C5—C6—H6	106.0	C2—C15—H15B	110.1
C12—C6—H6	106.0	H15A—C15—H15B	108.4
C8—C7—C6	111.77 (15)	C17—O16—C15	116.25 (13)
C8—C7—H7A	109.3	O24—C17—O16	124.84 (15)
C6—C7—H7A	109.3	O24—C17—C18	123.15 (14)
C8—C7—H7B	109.3	O16—C17—C18	112.00 (14)
C6—C7—H7B	109.3	C19—C18—C23	120.27 (14)
H7A—C7—H7B	107.9	C19—C18—C17	117.49 (15)
C7—C8—C9	112.11 (14)	C23—C18—C17	122.24 (13)
C7—C8—H8A	109.2	C20—C19—C18	118.97 (15)
C9—C8—H8A	109.2	C20—C19—H19	120.5
C7—C8—H8B	109.2	C18—C19—H19	120.5
C9—C8—H8B	109.2	C21—C20—C19	122.72 (14)
H8A—C8—H8B	107.9	C21—C20—N28	119.29 (14)
C10—C9—C11	111.20 (15)	C19—C20—N28	117.99 (15)
C10—C9—C8	109.96 (15)	C20—C21—C22	116.46 (14)
C11—C9—C8	112.06 (15)	C20—C21—H21	121.8
C10—C9—H9	107.8	C22—C21—H21	121.8
C11—C9—H9	107.8	C23—C22—C21	123.38 (15)
C8—C9—H9	107.8	C23—C22—N25	118.12 (13)
C5—C10—C9	112.88 (14)	C21—C22—N25	118.50 (13)
C5—C10—H10A	109.0	C22—C23—C18	118.20 (14)
C9—C10—H10A	109.0	C22—C23—H23	120.9
C5—C10—H10B	109.0	C18—C23—H23	120.9
C9—C10—H10B	109.0	O26—N25—O27	124.54 (14)
H10A—C10—H10B	107.8	O26—N25—C22	117.82 (13)
C9—C11—H11A	109.5	O27—N25—C22	117.64 (12)
C9—C11—H11B	109.5	O30—N28—O29	124.03 (13)
H11A—C11—H11B	109.5	O30—N28—C20	117.93 (13)
C9—C11—H11C	109.5	O29—N28—C20	118.03 (14)

C5—O1—C2—C15	145.19 (13)	C5—C6—C12—C13	153.37 (16)
C5—O1—C2—C3	21.05 (15)	O1—C2—C15—O16	−70.24 (16)
O1—C2—C3—O4	−33.31 (15)	C3—C2—C15—O16	45.44 (18)
C15—C2—C3—O4	−152.61 (12)	C2—C15—O16—C17	−173.43 (12)
C2—C3—O4—C5	33.85 (16)	C15—O16—C17—O24	−7.2 (2)
C3—O4—C5—O1	−21.48 (16)	C15—O16—C17—C18	171.59 (12)
C3—O4—C5—C10	96.20 (14)	O24—C17—C18—C19	4.1 (2)
C3—O4—C5—C6	−140.74 (14)	O16—C17—C18—C19	−174.70 (13)
C2—O1—C5—O4	−0.87 (16)	O24—C17—C18—C23	−176.18 (15)
C2—O1—C5—C10	−120.27 (13)	O16—C17—C18—C23	5.01 (19)
C2—O1—C5—C6	117.59 (14)	C23—C18—C19—C20	1.0 (2)
O4—C5—C6—C7	−66.69 (17)	C17—C18—C19—C20	−179.32 (13)
O1—C5—C6—C7	176.87 (13)	C18—C19—C20—C21	−1.0 (2)
C10—C5—C6—C7	56.32 (18)	C18—C19—C20—N28	178.53 (13)
O4—C5—C6—C12	63.30 (19)	C19—C20—C21—C22	0.6 (2)
O1—C5—C6—C12	−53.14 (19)	N28—C20—C21—C22	−178.93 (13)
C10—C5—C6—C12	−173.69 (15)	C20—C21—C22—C23	−0.1 (2)
C5—C6—C7—C8	−56.89 (18)	C20—C21—C22—N25	−179.81 (12)
C12—C6—C7—C8	173.69 (14)	C21—C22—C23—C18	0.2 (2)
C6—C7—C8—C9	56.6 (2)	N25—C22—C23—C18	179.83 (13)
C7—C8—C9—C10	−53.50 (19)	C19—C18—C23—C22	−0.6 (2)
C7—C8—C9—C11	−177.71 (18)	C17—C18—C23—C22	179.73 (14)
O4—C5—C10—C9	65.68 (16)	C23—C22—N25—O26	−0.60 (19)
O1—C5—C10—C9	−178.11 (12)	C21—C22—N25—O26	179.08 (14)
C6—C5—C10—C9	−56.33 (18)	C23—C22—N25—O27	179.99 (13)
C11—C9—C10—C5	178.43 (15)	C21—C22—N25—O27	−0.33 (19)
C8—C9—C10—C5	53.72 (17)	C21—C20—N28—O30	176.82 (13)
C7—C6—C12—C14	43.7 (2)	C19—C20—N28—O30	−2.68 (19)
C5—C6—C12—C14	−83.3 (2)	C21—C20—N28—O29	−2.41 (19)
C7—C6—C12—C13	−79.62 (19)	C19—C20—N28—O29	178.08 (13)

Experimental details

Crystal data
Chemical formula	C₂₀H₂₆N₂O₈
M_r	422.43
Crystal system, space group	Monoclinic, P2₁
Temperature (K)	100
a, b, c (Å)	9.4396 (5), 5.8825 (3), 19.6719 (10)
β (°)	103.923 (3)
V (Å³)	1060.26 (9)
Z	2
Radiation type	Cu Kα
µ (mm⁻¹)	0.87
Crystal size (mm)	0.38 × 0.09 × 0.02

Data collection
Diffractometer	Bruker SMART APEXII CCD area-detector diffractometer
Absorption correction	Multi-scan (SADABS; Bruker, 2008)
T_min, T_max	0.602, 0.977
No. of measured, independent and observed [I > 2σ(I)] reflections	16481, 3275, 3254
R_int	0.025
(sin θ/λ)_max (Å⁻¹)	0.602

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.018, 0.045, 1.06
No. of reflections	3275
No. of parameters	276
No. of restraints	1
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.10, −0.11
Absolute structure	Flack (1983), 1131 Friedel pairs
Absolute structure parameter	0.03 (13)

Computer programs: APEX2 (Bruker, 2008), SAINT (Bruker, 2008), SHELXTL (Sheldrick, 2008).

Acknowledgements

We would like to thank the Mansfield University Foundation for supporting this research.

References

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