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Acta Cryst. (2008). E64, o854    [ doi:10.1107/S1600536808005990 ]

Methyl 9H-xanthene-9-carboxylate

P. M. Dean, J. Turanjanin and D. R. MacFarlane

Abstract top

The title compound, C15H12O3, was obtained unintentionally as the by-product of an attempted recrystallization from methanol of propantheline bromide, an antimuscarinic drug. The xanthone unit is folded, with a dihedral angle of 24.81 (9)° between the benzene rings. The ester substituent adopts a trans staggered conformation, with a C-C-O-C torsion angle of 178.4 (1)°. The molecules pack in distinct layers, facilitated by C-H...[pi] and weak [pi]-[pi] ring interactions. A weak C-H...O interaction also occurs; however, no classical hydrogen bonding is observed.

Comment top

It was found that propantheline bromide (George et al., 2007) undergoes facile transesterification by methanol to produce the by-product 9H-xanthene-9-carboxylic acid methyl ester (Avdovich et al., 1986). Surprisingly, the structural elucidation of this analogue (Fig. 1) has not been reported in the literature until now. Now the structural determination and analysis is briefly described.

The xanthone unit is bent, with the aromatic planes oriented to each other by an interplanar angle of 24.81 (9)°. The ester substituent adopts a trans staggered conformation with a C7—C14—O3—C15 torsion angle of 178.4 (1)°. Additionally, as is typical of an ester, the O3—C14 distance is 1.326 (2) Å and the O3—C15 distance is 1.448 (2) Å, indicating the sp2 hybridization of C14.

The overall packing is shown in Fig. 2. Molecules are related by centres of symmetry, resulting in a head-to-head arrangement, that packs in aromatic and non-aromatic layers lying parallel to the (100) plane. Fig. 2 displays the orientation of the molecules, facilitating the weak C—H···O hydrogen bonding between the methyl and carbonyl groups (distance: C15—H15C···O2i (i = x,y - 1,z) 3.407 (2) Å - see Table 1) and the C—H···π and weak π···π ring interactions (Table 2). A short range contact, 2.683 (2) Å, also occurs between the aromatic C4—H4 and the carbonyl oxygen O2 (distance: C4—H4···O2ii (ii = x,1 - y,-1/2 + z).

Related literature top

For details of the first spectroscopic evidence of the transesterification of propantheline bromide by methanol to 9H-xanthene-9-carboxylic acid methyl ester, see: Avdovich et al. (1986). For a description of the comparative effectiveness of propantheline bromide for the treatment of neurogenic detrusor overactivity, see: George et al. (2007).

Experimental top

The title compound was obtained unintentionally as the product of an attempted recrystallization of propantheline bromide (50 mg) in methanol (2 ml) at room temperature. Crystals resulted after 6 days; these were coated with Paratone N oil (Exxon Chemical Co., TX, USA) immediately after isolation and cooled in a stream of nitrogen vapour on the diffractometer. Melting point: 360.7 K.

Refinement top

All H atoms were observed in difference syntheses and were then placed in geometrically idealized positions and constrained to ride on their parent atoms with C—H distances in the range 0.95–1.00 Å. Uiso(H) = xUeq(C), where x = 1.5 for methyl and 1.2 for all other C atoms.

Computing details top

Data collection: APEX2 (Bruker, 2005); cell refinement: APEX2 (Bruker, 2005); data reduction: APEX2 (Bruker, 2005); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: POV-RAY for Windows (Persistence of Vision, 1999); software used to prepare material for publication: PLATON (Spek, 2003).

Figures top
[Figure 1] Fig. 1. The molecular structure of the title compound, with displacement ellipsoids drawn at the 50% probability level and hydrogen atoms as spheres of arbitrary radius.
[Figure 2] Fig. 2. A ball-and-stick representation of the unit-cell contents, viewed down the b axis.
Methyl 9H-xanthene-9-carboxylate top
Crystal data top
C15H12O3F000 = 1008
Mr = 240.25Dx = 1.372 Mg m−3
Monoclinic, C2/cMelting point: 360.7 K
Hall symbol: -C 2ycMo Kα radiation
λ = 0.71073 Å
a = 25.6601 (16) ÅCell parameters from 1829 reflections
b = 5.7624 (3) Åθ = 2.6–25.8º
c = 15.7578 (9) ŵ = 0.10 mm−1
β = 92.933 (4)ºT = 123 (2) K
V = 2327.0 (2) Å3Prismatic, colourless
Z = 80.50 × 0.50 × 0.50 mm
Data collection top
Bruker KappaAPEXII
diffractometer		2672 independent reflections
Radiation source: fine-focus sealed tube1985 reflections with I > 2σ(I)
Monochromator: graphiteRint = 0.050
T = 123(2) Kθmax = 27.5º
0.5° frames in φ and ω scansθmin = 1.6º
Absorption correction: multi-scan
(SADABS; Bruker, 2005)		h = −33→33
Tmin = 0.932, Tmax = 0.954k = −7→7
11906 measured reflectionsl = −20→20
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.050H-atom parameters constrained
wR(F2) = 0.106  w = 1/[σ2(Fo2) + (0.0212P)2 + 2.7981P]
where P = (Fo2 + 2Fc2)/3
S = 1.06(Δ/σ)max < 0.001
2672 reflectionsΔρmax = 0.20 e Å−3
166 parametersΔρmin = −0.21 e Å−3
Primary atom site location: structure-invariant direct methodsExtinction correction: none
Crystal data top
C15H12O3V = 2327.0 (2) Å3
Mr = 240.25Z = 8
Monoclinic, C2/cMo Kα
a = 25.6601 (16) ŵ = 0.10 mm−1
b = 5.7624 (3) ÅT = 123 (2) K
c = 15.7578 (9) Å0.50 × 0.50 × 0.50 mm
β = 92.933 (4)º
Data collection top
Bruker KappaAPEXII
diffractometer		2672 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 2005)		1985 reflections with I > 2σ(I)
Tmin = 0.932, Tmax = 0.954Rint = 0.050
11906 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.050166 parameters
wR(F2) = 0.106H-atom parameters constrained
S = 1.06Δρmax = 0.20 e Å−3
2672 reflectionsΔρmin = −0.21 e Å−3
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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
O10.33199 (5)−0.0433 (2)0.46758 (8)0.0291 (4)
O30.44741 (5)0.1331 (2)0.55663 (8)0.0317 (4)
C10.35919 (6)0.0509 (3)0.40209 (11)0.0246 (4)
O20.46182 (5)0.5104 (2)0.57999 (10)0.0460 (5)
C50.41061 (7)0.3418 (3)0.33969 (11)0.0296 (5)
H50.42850.48600.34320.036*
C80.34065 (6)0.3209 (3)0.54356 (11)0.0270 (5)
C140.43644 (7)0.3568 (3)0.54706 (11)0.0269 (4)
C90.32151 (7)0.4651 (4)0.60572 (11)0.0340 (5)
H90.33740.61170.61660.041*
C40.40994 (7)0.2167 (4)0.26464 (12)0.0344 (5)
H40.42750.27440.21740.041*
C20.35812 (7)−0.0765 (3)0.32741 (11)0.0296 (5)
H20.3400−0.22020.32360.036*
C120.27490 (7)0.0372 (4)0.57561 (11)0.0320 (5)
H120.2591−0.10990.56530.038*
C100.27969 (7)0.3977 (4)0.65182 (12)0.0404 (6)
H100.26680.49830.69360.048*
C110.25674 (7)0.1837 (4)0.63695 (12)0.0383 (6)
H110.22820.13690.66910.046*
C30.38359 (7)0.0071 (4)0.25876 (12)0.0336 (5)
H30.3831−0.07920.20740.040*
C60.38552 (6)0.2600 (3)0.41010 (11)0.0255 (4)
C70.38629 (7)0.3930 (3)0.49288 (11)0.0265 (5)
H70.38280.56220.47960.032*
C130.31655 (6)0.1086 (3)0.52950 (11)0.0266 (4)
C150.49380 (7)0.0797 (4)0.60921 (12)0.0349 (5)
H15A0.49110.15050.66540.052*
H15B0.52450.14150.58250.052*
H15C0.4972−0.08890.61540.052*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O10.0329 (7)0.0252 (7)0.0294 (7)0.0015 (5)0.0027 (5)−0.0008 (5)
O30.0293 (7)0.0257 (7)0.0385 (8)0.0029 (6)−0.0121 (5)−0.0011 (6)
C10.0234 (8)0.0252 (10)0.0251 (9)0.0051 (7)−0.0011 (7)−0.0002 (7)
O20.0419 (8)0.0328 (8)0.0611 (10)−0.0017 (7)−0.0166 (7)−0.0116 (7)
C50.0264 (9)0.0298 (10)0.0324 (10)0.0028 (8)−0.0027 (7)0.0057 (8)
C80.0260 (9)0.0296 (10)0.0248 (9)0.0088 (7)−0.0044 (7)−0.0016 (7)
C140.0281 (9)0.0249 (10)0.0276 (9)0.0000 (8)0.0010 (7)−0.0043 (8)
C90.0329 (10)0.0396 (12)0.0284 (10)0.0133 (9)−0.0089 (8)−0.0074 (8)
C40.0309 (10)0.0457 (13)0.0267 (10)0.0086 (9)0.0019 (7)0.0050 (9)
C20.0288 (9)0.0280 (10)0.0314 (10)0.0060 (8)−0.0048 (7)−0.0042 (8)
C120.0286 (9)0.0384 (11)0.0285 (10)0.0052 (8)−0.0038 (7)0.0087 (8)
C100.0360 (10)0.0603 (15)0.0245 (10)0.0203 (10)−0.0028 (8)−0.0072 (9)
C110.0298 (10)0.0604 (15)0.0246 (10)0.0124 (10)0.0005 (7)0.0091 (9)
C30.0321 (10)0.0426 (12)0.0254 (10)0.0111 (9)−0.0044 (7)−0.0061 (8)
C60.0248 (8)0.0244 (10)0.0267 (9)0.0050 (7)−0.0040 (7)0.0002 (7)
C70.0310 (9)0.0204 (9)0.0277 (9)0.0051 (7)−0.0037 (7)−0.0015 (7)
C130.0279 (9)0.0303 (10)0.0210 (9)0.0082 (8)−0.0030 (7)0.0017 (7)
C150.0261 (9)0.0417 (12)0.0361 (11)0.0036 (8)−0.0071 (8)0.0010 (9)
Geometric parameters (Å, °) top
O1—C131.384 (2)C4—C31.385 (3)
O1—C11.386 (2)C4—H40.9500
O3—C141.326 (2)C2—C31.379 (3)
O3—C151.448 (2)C2—H20.9500
C1—C61.384 (2)C12—C111.382 (3)
C1—C21.386 (2)C12—C131.385 (2)
O2—C141.201 (2)C12—H120.9500
C5—C41.384 (3)C10—C111.381 (3)
C5—C61.393 (2)C10—H100.9500
C5—H50.9500C11—H110.9500
C8—C131.384 (3)C3—H30.9500
C8—C91.393 (2)C6—C71.512 (2)
C8—C71.509 (2)C7—H71.0000
C14—C71.522 (2)C15—H15A0.9800
C9—C101.382 (3)C15—H15B0.9800
C9—H90.9500C15—H15C0.9800
C13—O1—C1116.79 (14)C11—C10—H10120.1
C14—O3—C15115.78 (14)C9—C10—H10120.1
C6—C1—O1122.37 (15)C10—C11—C12120.52 (18)
C6—C1—C2121.80 (16)C10—C11—H11119.7
O1—C1—C2115.83 (16)C12—C11—H11119.7
C4—C5—C6121.21 (18)C2—C3—C4120.11 (17)
C4—C5—H5119.4C2—C3—H3119.9
C6—C5—H5119.4C4—C3—H3119.9
C13—C8—C9117.98 (17)C1—C6—C5117.73 (16)
C13—C8—C7120.76 (15)C1—C6—C7120.31 (16)
C9—C8—C7121.26 (17)C5—C6—C7121.95 (16)
O2—C14—O3124.06 (17)C8—C7—C6109.91 (15)
O2—C14—C7124.42 (16)C8—C7—C14108.79 (14)
O3—C14—C7111.45 (15)C6—C7—C14112.80 (14)
C10—C9—C8120.9 (2)C8—C7—H7108.4
C10—C9—H9119.6C6—C7—H7108.4
C8—C9—H9119.6C14—C7—H7108.4
C5—C4—C3119.72 (18)C8—C13—O1122.03 (15)
C5—C4—H4120.1C8—C13—C12121.96 (17)
C3—C4—H4120.1O1—C13—C12116.00 (17)
C3—C2—C1119.42 (18)O3—C15—H15A109.5
C3—C2—H2120.3O3—C15—H15B109.5
C1—C2—H2120.3H15A—C15—H15B109.5
C11—C12—C13118.81 (19)O3—C15—H15C109.5
C11—C12—H12120.6H15A—C15—H15C109.5
C13—C12—H12120.6H15B—C15—H15C109.5
C11—C10—C9119.83 (18)
C13—O1—C1—C621.8 (2)C13—C8—C7—C622.5 (2)
C13—O1—C1—C2−157.71 (15)C9—C8—C7—C6−157.52 (16)
C15—O3—C14—O2−1.3 (3)C13—C8—C7—C14−101.48 (18)
C15—O3—C14—C7−178.43 (14)C9—C8—C7—C1478.5 (2)
C13—C8—C9—C100.0 (3)C1—C6—C7—C8−22.1 (2)
C7—C8—C9—C10179.99 (16)C5—C6—C7—C8157.52 (16)
C6—C5—C4—C30.5 (3)C1—C6—C7—C1499.48 (19)
C6—C1—C2—C3−0.5 (3)C5—C6—C7—C14−80.9 (2)
O1—C1—C2—C3179.03 (15)O2—C14—C7—C8−105.6 (2)
C8—C9—C10—C110.6 (3)O3—C14—C7—C871.48 (18)
C9—C10—C11—C12−0.7 (3)O2—C14—C7—C6132.14 (19)
C13—C12—C11—C100.1 (3)O3—C14—C7—C6−50.7 (2)
C1—C2—C3—C40.0 (3)C9—C8—C13—O1178.26 (15)
C5—C4—C3—C20.0 (3)C7—C8—C13—O1−1.7 (2)
O1—C1—C6—C5−178.53 (15)C9—C8—C13—C12−0.6 (3)
C2—C1—C6—C51.0 (2)C7—C8—C13—C12179.41 (16)
O1—C1—C6—C71.1 (2)C1—O1—C13—C8−21.5 (2)
C2—C1—C6—C7−179.37 (15)C1—O1—C13—C12157.43 (15)
C4—C5—C6—C1−1.0 (2)C11—C12—C13—C80.5 (3)
C4—C5—C6—C7179.39 (16)C11—C12—C13—O1−178.37 (15)
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
C15—H15C···O2i0.982.533.407 (3)149
C3—H3···Cg2ii0.952.953.668 (2)133
C11—H11···Cg1iii0.953.183.825 (2)127
C15—H15B···Cg1iv0.983.063.432 (2)104
C15—H15C···Cg1iv0.983.113.432 (2)101
Symmetry codes: (i) x, y−1, z; (ii) x, −y, z−1/2; (iii) −x+1/2, −y+1/2, −z+1; (iv) −x+1, −y, −z+1.
Table 1
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
C15—H15C···O2i0.982.533.407 (3)149
C3—H3···Cg2ii0.952.953.668 (2)133
C11—H11···Cg1iii0.953.183.825 (2)127
C15—H15B···Cg1iv0.983.063.432 (2)104
C15—H15C···Cg1iv0.983.113.432 (2)101
Symmetry codes: (i) x, y−1, z; (ii) x, −y, z−1/2; (iii) −x+1/2, −y+1/2, −z+1; (iv) −x+1, −y, −z+1.
Table 2
Geometrical parameters (Å, °) of the inter-ring π—π interactions. α is the dihedral angle between planes I and J, CgI is the centroid of plane I and CgJ the centroid of plane J. top
CgICgJCg···CgαSymmetry position of CgJ
Cg1Cg25.590 (1)59.44x,1-y,-1/2+z
Cg1Cg24.944 (1)24.811/2-x,1/2-y,1-z
Cg2Cg14.863 (1)59.44x,-y,1/2+z
Cg2Cg23.684 (1)0.031/2-x,1/2-y,1-z
Notes: Cg1 is the centroid of ring C1/C6; Cg2 is the centroid of ring C8/C13.
Acknowledgements top

PMD is grateful to Monash University for the Monash Graduate Scholarship and Monash International Postgraduate Research Scholarship, and to Monash University, School of Chemistry for funding for JT.

references
References top

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Bruker (2005). APEX2. Bruker AXS Inc., Madison, Wisconsin, USA.

George, J., Tharion, G., Richard, J., Macaden, A. S., Thomas, R. & Bhattacharji, S. (2007). The Scientific World Journal, 7, 1683–1690.

Persistence of Vision (1999). POV-RAY for Windows. Persistence of Vision Development Team, Victoria, Australia.

Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122.

Spek, A. L. (2003). J. Appl. Cryst. 36, 7–13.