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Ethyl (E)-2-(2,7-di­methyl-5-oxo-4H,5H-pyrano[4,3-b]pyran-4-yl­­idene)acetate

aLaboratoire de Chimie Organique et Analytique, Université Sultan Moulay Slimane, Faculté des Sciences et Techniques, Béni-Mellal, BP 523, Morocco, and bLaboratoire de Chimie du Solide Appliquée, Faculty of Sciences, Mohammed V University in Rabat, Avenue Ibn Battouta, BP 1014, Rabat, Morocco
*Correspondence e-mail: o_bassou@yahoo.com

Edited by H. Stoeckli-Evans, University of Neuchâtel, Switzerland (Received 25 January 2017; accepted 8 February 2017; online 14 February 2017)

In the title compound, C14H14O5, the two heterocyclic rings are coplanar (r.m.s. deviation = 0.008 Å), with the largest deviation from the mean plane being 0.012 (1) Å. The mean plane through the acetate group is inclined slightly with respect to the oxo­pyrano[4,3-b]pyran-4-yl system, as indicated by the dihedral angle of 1.70 (7)° between them. Two intra­molecular hydrogen bonds, completing S(6) ring motifs, are observed in the mol­ecule. In the crystal, mol­ecules are linked by weak C—H⋯O hydrogen bonds involving the same acceptor atom, forming chains propagating along the c-axis direction and enclosing R21(6) ring motifs. The chains are linked via offset ππ inter­actions [inter­centroid distance = 3.622 (1) Å], involving inversion-related oxo­pyrano[4,3-b]pyran-4-yl ring systems, forming slabs parallel to the bc plane.

3D view (loading...)
[Scheme 3D1]
Chemical scheme
[Scheme 1]

Structure description

Pyrones are among the most important heterocyclic structures in medicinal chemistry and specifically, 2-pyrones can be found in a wide range of medicinally significant natural products (Lee et al., 2000[Lee, Y. S., Kim, S. N., Lee, Y. S., Lee, J. Y., Lee, C.-K., Kim, H. S. & Park, H. (2000). Arch. Pharm. Pharm. Med. Chem. 333, 319-322.]; Fairlamb et al., 2004[Fairlamb, I. J. S., Marrison, L. R., Dickinson, J. M., Lu, F.-J. & Schmidt, J. P. (2004). Bioorg. Med. Chem. 12, 4285-4299.]; McGlacken & Fairlamb, 2005[McGlacken, G. P. & Fairlamb, I. J. S. (2005). Nat. Prod. Rep. 22, 369-385.]; Perchellet et al., 1998[Perchellet, E. M., Ladesich, J. B., Chen, Y., Sin, H.-S., Hua, D. H., Kraft, S. L. & Perchellet, J.-P. (1998). Anticancer Drugs, 9, 565-576.]; Defant et al., 2015[Defant, A., Mancini, I., Tomazzolli, R. & Balzarini, J. (2015). Arch. Pharm. Chem. Life Sci. 348, 23-33.]). As heterocyclic aromatic enols, they have a high acidity and dense functionality, which leads to a diverse reactivity profile. This means that 4-hy­droxy-2-pyrones are also useful precursors to a number of other structural units and versatile inter­mediates in organic synthesis (Burns et al., 2014[Burns, M. J., Ronson, T. O., Taylor, R. J. K. & Fairlamb, I. J. S. (2014). Beilstein J. Org. Chem. 10, 1159-1165.]; Aggarwal et al., 2013[Aggarwal, R., Rani, C., Kumar, R., Garg, G. & Sharmab, J. (2013). ARKIVOC, II, 120-134.]).

The mol­ecule of the title compound is build up from a bicyclic oxo­pyrano[4,3-b]pyran-4-yl­idene ring system linked to two methyl groups and one acetate group, as shown in Fig. 1[link]. The fused heterocyclic rings are virtually coplanar with the maximum deviation from the mean plane being 0.012 (2) Å for atom C9. The oxo­pyrano[4,3-b]pyran-4-yl system makes a dihedral angle of 1.70 (7)° with the mean plane through the acetate group. Two intra­molecular C—H⋯O contacts, enclosing S(6) ring motifs, are observed in the mol­ecule (Fig. 1[link] and Table 1[link]).

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
C4—H4⋯O4 0.93 2.20 2.883 (2) 130
C6—H6⋯O2 0.93 2.24 2.894 (2) 127
C12—H12⋯O4i 0.93 2.59 3.283 (2) 132
C13—H13C⋯O4i 0.96 2.59 3.398 (2) 143
Symmetry code: (i) [x, -y+{\script{1\over 2}}, z-{\script{1\over 2}}].
[Figure 1]
Figure 1
A view of the mol­ecular structure of the title compound, showing the atom labelling. Displacement ellipsoids are drawn at the 50% probability level. The intra­molecular C—H⋯O contacts are shown as dashed lines (see Table 1[link]).

In the crystal, mol­ecules are linked by weak C—H⋯O hydrogen bonds involving the same acceptor atom (see Table 1[link]), forming chains propagating along the c-axis direction and enclosing [R_{2}^{1}](6) ring motifs (Fig. 2[link]). The chains are linked via offset ππ inter­actions involving inversion-related oxo­pyrano[4,3-b]pyran-4-yl ring systems, [inter­centroid distance = 3.622 (1) Å], forming slabs parallel to the bc plane (Fig. 3[link]).

[Figure 2]
Figure 2
A partial view, normal to (110), of the crystal packing for the title compound, with hydrogen bonds shown as dashed lines (see Table 1[link]; only H atoms H4, H6, H12 and H13C have been included).
[Figure 3]
Figure 3
A view along the c axis of the crystal packing for the title compound, with the hydrogen bonds shown as dashed lines (see Table 1[link]; only H atoms H4, H6, H12 and H13C have been included).

Synthesis and crystallization

To a solution of 6-amino­uracil (1 mmol) in 25 ml of ethanol, 4-hy­droxy-6-methyl-2-pyrone (1.1 mmol) and drops of tri­ethyl­amine were added. The mixture was refluxed for 8 h. After cooling to room temperature, the solvent was removed under reduced pressure. The crude product was purified on silica gel using hexa­ne:ethyl acetate (2/8) as eluent. The title compound was recrystallized from ethanol giving colourless block-like crystals (yield: 54%, m.p. 376 K). It should be noted that in the reaction of 6-aminouracil with 4-hydroxy-6-methyl-2-pyrone, under reflux of ethanol in the presence of Et3N, we observed another competitive reaction between two molecules of 4-hydroxy-6 -methyl-2-pyrone, this reaction is kinetically favored over the first reaction. Details are given in the Supporting information.

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2[link].

Table 2
Experimental details

Crystal data
Chemical formula C14H14O5
Mr 262.25
Crystal system, space group Monoclinic, P21/c
Temperature (K) 296
a, b, c (Å) 9.5679 (12), 11.4330 (13), 12.7993 (15)
β (°) 108.257 (4)
V3) 1329.6 (3)
Z 4
Radiation type Mo Kα
μ (mm−1) 0.10
Crystal size (mm) 0.32 × 0.26 × 0.21
 
Data collection
Diffractometer Bruker X8 APEX
Absorption correction Multi-scan (SADABS; Krause et al., 2015[Krause, L., Herbst-Irmer, R., Sheldrick, G. M. & Stalke, D. (2015). J. Appl. Cryst. 48, 3-10.])
Tmin, Tmax 0.663, 0.746
No. of measured, independent and observed [I > 2σ(I)] reflections 16353, 2939, 1909
Rint 0.037
(sin θ/λ)max−1) 0.641
 
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.043, 0.137, 1.03
No. of reflections 2939
No. of parameters 180
H-atom treatment H-atom parameters constrained
Δρmax, Δρmin (e Å−3) 0.17, −0.15
Computer programs: APEX2 and SAINT (Bruker, 2009[Bruker (2009). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]), SHELXT2014 (Sheldrick, 2015a[Sheldrick, G. M. (2015a). Acta Cryst. A71, 3-8.]), SHELXL2014 (Sheldrick, 2015b[Sheldrick, G. M. (2015b). Acta Cryst. C71, 3-8.]), ORTEP-3 for Windows (Farrugia, 2012[Farrugia, L. J. (2012). J. Appl. Cryst. 45, 849-854.]), Mercury (Macrae et al., 2008[Macrae, C. F., Bruno, I. J., Chisholm, J. A., Edgington, P. R., McCabe, P., Pidcock, E., Rodriguez-Monge, L., Taylor, R., van de Streek, J. & Wood, P. A. (2008). J. Appl. Cryst. 41, 466-470.]), PLATON (Spek, 2009[Spek, A. L. (2009). Acta Cryst. D65, 148-155.]) and publCIF (Westrip, 2010[Westrip, S. P. (2010). J. Appl. Cryst. 43, 920-925.]).

Structural data


Computing details top

Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT (Bruker, 2009); program(s) used to solve structure: SHELXT2014 (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015b); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012) and Mercury (Macrae et al., 2008); software used to prepare material for publication: PLATON (Spek, 2009) and publCIF (Westrip, 2010).

Ethyl (E)-2-(2,7-dimethyl-5-oxo-4H,5H-pyrano[4,3-b]pyran-4-ylidene)acetate top
Crystal data top
C14H14O5Dx = 1.310 Mg m3
Mr = 262.25Melting point: 376 K
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
a = 9.5679 (12) ÅCell parameters from 2939 reflections
b = 11.4330 (13) Åθ = 2.5–27.1°
c = 12.7993 (15) ŵ = 0.10 mm1
β = 108.257 (4)°T = 296 K
V = 1329.6 (3) Å3Block, colourless
Z = 40.32 × 0.26 × 0.21 mm
F(000) = 552
Data collection top
Bruker X8 APEX
diffractometer
2939 independent reflections
Radiation source: fine-focus sealed tube1909 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.037
φ and ω scansθmax = 27.1°, θmin = 2.5°
Absorption correction: multi-scan
(SADABS; Krause et al., 2015)
h = 1212
Tmin = 0.663, Tmax = 0.746k = 1414
16353 measured reflectionsl = 1316
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.043Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.137H-atom parameters constrained
S = 1.03 w = 1/[σ2(Fo2) + (0.0699P)2 + 0.1184P]
where P = (Fo2 + 2Fc2)/3
2939 reflections(Δ/σ)max < 0.001
180 parametersΔρmax = 0.17 e Å3
0 restraintsΔρmin = 0.15 e Å3
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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
C10.7176 (3)0.4822 (2)1.10578 (18)0.1053 (9)
H1A0.78960.50341.17420.158*
H1B0.63840.53761.08840.158*
H1C0.68010.40551.11220.158*
C20.7864 (2)0.4820 (2)1.01765 (16)0.0901 (7)
H2A0.82500.55901.01050.108*
H2B0.86700.42631.03450.108*
C30.7183 (2)0.43027 (15)0.82769 (14)0.0584 (5)
C40.59172 (17)0.40172 (14)0.73274 (13)0.0523 (4)
H40.50000.39880.74330.063*
C50.59770 (16)0.37903 (12)0.62997 (12)0.0442 (4)
C60.73205 (17)0.38065 (13)0.60097 (14)0.0496 (4)
H60.81980.39600.65630.060*
C70.73778 (16)0.36155 (14)0.50021 (14)0.0508 (4)
C80.48137 (16)0.33460 (12)0.43348 (13)0.0453 (4)
C90.46732 (15)0.35306 (12)0.53543 (12)0.0420 (4)
C100.31964 (17)0.34808 (14)0.54336 (13)0.0488 (4)
C110.22563 (17)0.30720 (14)0.34851 (13)0.0515 (4)
C120.35992 (17)0.31137 (14)0.33862 (14)0.0519 (4)
H120.37390.29930.27070.062*
C130.08513 (19)0.2864 (2)0.26002 (16)0.0752 (6)
H13A0.02810.35710.24610.130 (10)*
H13B0.03100.22590.28240.109 (8)*
H13C0.10520.26270.19420.100 (7)*
C140.8690 (2)0.36234 (18)0.46180 (18)0.0702 (6)
H14A0.88130.28650.43380.109 (8)*
H14B0.95480.38150.52220.100 (7)*
H14C0.85580.41960.40460.102 (8)*
O10.67347 (14)0.44936 (12)0.91578 (10)0.0756 (4)
O20.84654 (14)0.43692 (14)0.83266 (11)0.0822 (5)
O30.61171 (11)0.33840 (10)0.41328 (9)0.0557 (3)
O40.28225 (13)0.36313 (13)0.62435 (10)0.0714 (4)
O50.20544 (11)0.32427 (10)0.44793 (9)0.0546 (3)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.110 (2)0.129 (2)0.0675 (13)0.0096 (16)0.0138 (14)0.0315 (14)
C20.0758 (15)0.1147 (18)0.0611 (12)0.0024 (13)0.0055 (11)0.0259 (12)
C30.0485 (11)0.0619 (11)0.0556 (10)0.0028 (8)0.0030 (8)0.0001 (8)
C40.0406 (9)0.0584 (10)0.0531 (10)0.0007 (7)0.0079 (7)0.0046 (7)
C50.0348 (8)0.0411 (8)0.0515 (9)0.0014 (6)0.0061 (7)0.0063 (6)
C60.0318 (8)0.0524 (9)0.0573 (10)0.0009 (6)0.0034 (7)0.0027 (7)
C70.0304 (8)0.0516 (9)0.0676 (11)0.0000 (6)0.0111 (8)0.0013 (8)
C80.0329 (8)0.0445 (8)0.0577 (10)0.0009 (6)0.0132 (7)0.0020 (7)
C90.0326 (8)0.0417 (8)0.0484 (9)0.0006 (6)0.0079 (7)0.0046 (6)
C100.0350 (8)0.0586 (10)0.0495 (9)0.0038 (7)0.0084 (8)0.0085 (7)
C110.0386 (9)0.0580 (10)0.0532 (9)0.0056 (7)0.0075 (7)0.0067 (7)
C120.0400 (9)0.0636 (10)0.0510 (9)0.0047 (7)0.0125 (7)0.0103 (7)
C130.0416 (10)0.1101 (17)0.0657 (12)0.0123 (11)0.0050 (9)0.0200 (11)
C140.0401 (10)0.0861 (15)0.0874 (14)0.0025 (9)0.0243 (10)0.0080 (12)
O10.0609 (8)0.1019 (10)0.0552 (7)0.0007 (7)0.0055 (6)0.0196 (7)
O20.0457 (8)0.1220 (12)0.0674 (9)0.0020 (7)0.0014 (7)0.0103 (8)
O30.0336 (6)0.0732 (8)0.0607 (7)0.0042 (5)0.0151 (5)0.0125 (5)
O40.0439 (7)0.1199 (11)0.0522 (7)0.0059 (7)0.0176 (6)0.0078 (7)
O50.0321 (6)0.0744 (8)0.0546 (7)0.0077 (5)0.0097 (5)0.0009 (5)
Geometric parameters (Å, º) top
C1—C21.473 (3)C7—C141.485 (2)
C1—H1A0.9600C8—O31.3513 (18)
C1—H1B0.9600C8—C91.369 (2)
C1—H1C0.9600C8—C121.418 (2)
C2—O11.458 (2)C9—C101.449 (2)
C2—H2A0.9700C10—O41.2102 (19)
C2—H2B0.9700C10—O51.3869 (18)
C3—O21.211 (2)C11—C121.331 (2)
C3—O11.344 (2)C11—O51.3596 (19)
C3—C41.459 (2)C11—C131.481 (2)
C4—C51.359 (2)C12—H120.9300
C4—H40.9300C13—H13A0.9600
C5—C61.446 (2)C13—H13B0.9600
C5—C91.471 (2)C13—H13C0.9600
C6—C71.326 (2)C14—H14A0.9600
C6—H60.9300C14—H14B0.9600
C7—O31.3864 (18)C14—H14C0.9600
C2—C1—H1A109.5C9—C8—C12123.09 (14)
C2—C1—H1B109.5C8—C9—C10116.72 (14)
H1A—C1—H1B109.5C8—C9—C5120.27 (13)
C2—C1—H1C109.5C10—C9—C5123.00 (14)
H1A—C1—H1C109.5O4—C10—O5114.81 (14)
H1B—C1—H1C109.5O4—C10—C9127.65 (15)
O1—C2—C1107.53 (19)O5—C10—C9117.54 (14)
O1—C2—H2A110.2C12—C11—O5120.55 (14)
C1—C2—H2A110.2C12—C11—C13127.24 (17)
O1—C2—H2B110.2O5—C11—C13112.20 (14)
C1—C2—H2B110.2C11—C12—C8118.81 (16)
H2A—C2—H2B108.5C11—C12—H12120.6
O2—C3—O1122.03 (16)C8—C12—H12120.6
O2—C3—C4128.38 (18)C11—C13—H13A109.5
O1—C3—C4109.59 (15)C11—C13—H13B109.5
C5—C4—C3124.97 (16)H13A—C13—H13B109.5
C5—C4—H4117.5C11—C13—H13C109.5
C3—C4—H4117.5H13A—C13—H13C109.5
C4—C5—C6123.81 (14)H13B—C13—H13C109.5
C4—C5—C9123.55 (14)C7—C14—H14A109.5
C6—C5—C9112.62 (14)C7—C14—H14B109.5
C7—C6—C5123.96 (15)H14A—C14—H14B109.5
C7—C6—H6118.0C7—C14—H14C109.5
C5—C6—H6118.0H14A—C14—H14C109.5
C6—C7—O3121.42 (14)H14B—C14—H14C109.5
C6—C7—C14128.16 (16)C3—O1—C2116.73 (16)
O3—C7—C14110.42 (15)C8—O3—C7118.41 (12)
O3—C8—C9123.32 (14)C11—O5—C10123.28 (13)
O3—C8—C12113.58 (14)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C4—H4···O40.932.202.883 (2)130
C6—H6···O20.932.242.894 (2)127
C12—H12···O4i0.932.593.283 (2)132
C13—H13C···O4i0.962.593.398 (2)143
Symmetry code: (i) x, y+1/2, z1/2.
 

Acknowledgements

The authors thank the Unit of Support for Technical and Scientific Research (UATRS, CNRST) for the X-ray measurements.

Funding information

Funding for this research was provided by: University Sultan Moulay Slimane, Beni-Mellal, Morocco

References

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