organic compounds
Ethyl 2,2-dimethyl-4-oxo-6-phenyl-3,4-dihydro-2H-pyran-5-carboxylate
aPG & Research Department of Physics, National College (Autonomous), Tiruchirappalli 620 001, Tamilnadu, India, bSchool of Chemistry, Bharathidasan University, Palkalaiperur, Tiruchirappalli 620 024, Tamilnadu, India, and cLaboratorio de Políimeros, Centro de Química Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla (BUAP), Complejo de Ciencias, ICUAP, Edif. 103H, 22 Sur y San Claudio, C.P. 72570 Puebla, Puebla, Mexico
*Correspondence e-mail: sunvag@gmail.com
The title compound, C16H18O4, is a derivative of 3,4-dihydro-2H-pyran-4-one. The plane of the pyranone ring system forms a dihedral angle of 42.76 (10)° with that of the phenyl group. The is stabilized by C—H⋯O interactions that enclose an R21(6) ring motif and link the molecules into chains along the c axis. A short intramolecular O⋯O contact [2.942 (3) Å] gives rise to an S(5) motif.
Keywords: crystal structure; pyran; hydrogen bonding.
CCDC reference: 1520376
Structure description
Derivatives of the 4H-pyran-4-one heterocyclic system, also known as 4-pyrones or γ-pyrones, are usually quite stable crystalline compounds (Joule et al., 1995). They are reported as compounds acting as melanocortin receptors showing fungicidal, insecticidal, acaricidal, antiviral and anticonvulsant activities (Wang et al., 2006, and references therein). As part of our interest in the structural investigations of 4H-pyran-4-one derivatives, we report herein on the determination and the geometry optimization of the title compound ethyl 2,2-dimethyl-4-oxo-6-phenyl-3,4-dihydro-2H-pyran-5-carboxylate, (I). Theoretical calculations of the molecular structure, carried out using MOPAC2012's PM7 geometry optimization algorithm (Stewart, 2012; Maia et al., 2012), are in satisfactory agreement with the results of the X-ray analysis.
A perspective view of (I), with the atomic numbering scheme, is illustrated in Fig. 1. The 3,4-dihydro-2H-pyran-4-one moiety (atoms C7–C11/O1/O2) forms a dihedral angle of 42.76 (10)° with the plane of the phenyl group. The phenyl group is almost planar, with an r.m.s. deviation of the fitted atoms of 0.006 Å, whereas the pyran and 3,4-dihydro-2H-pyran-4-one moieties are not planar (r.m.s deviations = 0.179 and 0.194 Å, respectively).
The corresponding bond lengths in the pyran ring are in good agreement with those reported in the literature (Dinçer et al., 2004), except for the O1—C8 and C8—C9 bond lengths [1.476 (2) and 1.519 (3) Å, respectively], which have larger values when compared to the corresponding positions in the related structure (1.367 and 1.342 Å; Dinçer et al., 2004). This is due to the fact that the reported structure is a dihydropyran with two methyl substitutions at C8 of the pyran ring, while the related structure is a tetra-substituted pyran. It could also be evidenced from the fragment overlay (Gans & Shalloway, 2001) of 3,4-dihydro-2H-pyran-4-one moieties of (I) with the corresponding moiety in 3,5-bis(4-methylbenzoyl)-2,6-bis(4-methylphenyl)-4H-pyran-4-one, (II) (Dinçer et al., 2004) (r.m.s deviation = 1.072 Å). The corresponding positions in (I) is also superimposed with 4-(4-fluorophenyl)-6-methylamino-5-nitro-2-phenyl-4H-pyran-3-carbonitrile, (III) (Vishnupriya et al., 2013), gave an r.m.s deviation of 1.401 Å (Fig. 2).
Also, the pyran ring of (I) is puckered (puckering parameters: Q = 0.439 (2) Å, q2 = 0.348 (2) Å, q3 = 0.269 (2) Å θ = 52.3 (3)° and φ = 271.6 (4)°, with atom C8 deviating by 0.576 (2) Å from the C7/C9–C11/O1 plane; the ring is in a half-chair conformation. The relative conformation about the bond joining the 3,4-dihydro-2H-pyran-4-one moiety with the benzyl group of (I), defined by the C1—C6—C7—O1 and C5—C6—C7—C11 torsion angles, is (−)synclinal in both the [−42.0 (3) and −43.3 (3)°] and the optimized structure (−51.06 and −50.41°). Whereas the C1—C6—C7—C11 and C5—C6—C7—O1 torsion angles are (+)anticlinal in both the [138.6 (2) and 136.1 (2)°] and the optimized structure (129.70 and 128.83°).
A geometry optimization of (I) with a Parameterized Model 7 computation was performed using MOPAC2012. Hartree–Fock closed-shell (restricted) wavefunctions were used for calculations. The HOMO and LUMO energy levels were found to be −9.734 and −0.800 eV, respectively. The total energy and ).
of the title molecules are −3389.77227 eV and 5.358 Debye, respectively. In the geometry-optimized structure of (I), it was observed that the O1—C8 bond length decreased to 1.456 Å (1.476 Å in the crystal structure). Also, the C6—C7 bond length in the geometry-optimized structure increased to 1.468 Å (1.483 Å in the crystal structure). The O1—C7—C6 bond angle decreased from 110.42 to 109.81° and the O1—C8—C9 bond angle increased from 108.85 to 110.75°. A superimposed fit of (I) with its energy-minimized molecule gives an r.m.s. deviation of 0.452 Å (Fig. 3The interaction between C9—O2 and C15—O2 via atoms H9B and H15A, Table 1, enclosing an (6) ring motif, form a chain of molecules along the c axis (Fig. 4). A short intramolecular contact is also found between the atoms O2 and O4 [2.942 (3) Å], giving rise to an S(5) motif.
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When compared with a similar pyran derivative, i.e. 4-(4-fluorophenyl)-6-methylamino-5-nitro-2-phenyl-4H-pyran-3-carbonitrile (Vishnupriya et al., 2013), the six-membered central pyran ring adopts a boat conformation in the related structure, whereas it is in a half-chair conformation in (I). The variation in conformation between the two structures is also reflected in the dihedral angle between the central pyran ring and the phenyl ring at atom C7 [49.22 (2)° in the related structure and 39.39 (10)° in (I)].
Synthesis and crystallization
To a solution of ethyl benzoylacetate (192 mg, 1.0 mmol), CaCl2 (11 mg, 0.1 mmol), triethylamine (278 µl, 2.0 mmol) in dichloromethane (4 ml) was added senecioyl chloride (systematic name: 3-methylbut-2-enoyl chloride) (112 µl, 1.0 mmol) dropwise at 283 K. After completion of the addition, the reaction mixture was stirred at room temperature for 6 h. The progress of the reaction was monitored by (TLC). The reaction mixture was quenched with water, neutralized with dilute HCl, extracted with CH2Cl2 (2 × 8 ml) and washed with brine. The organic layer was separated, dried over anhydrous Na2SO4 and concentrated under reduced pressure. The crude product was purified by silica-gel (EtOAc/hexane = 2:8 v/v as eluent). The title compound was obtained as a colourless solid (yield 80%, 219 mg) which was crystallized from hexane/EtOAc (m.p. 351–353 K).
Refinement
Crystal data, data collection and structure .
details are summarized in Table 2Structural data
CCDC reference: 1520376
https://doi.org/10.1107/S2414314616019246/bv4006sup1.cif
contains datablock I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2414314616019246/bv4006Isup2.hkl
Supporting information file. DOI: https://doi.org/10.1107/S2414314616019246/bv4006Isup3.cml
Data collection: SMART (Bruker, 2008); cell
SAINT (Bruker, 2008); data reduction: SAINT (Bruker, 2008); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015); molecular graphics: QMOL (Gans & Shalloway, 2001), Mercury (Macrae et al., 2008), ORTEPIII (Burnett & Johnson, 1996) and MOPAC (Stewart, 2012); software used to prepare material for publication: WinGX (Farrugia, 2012) and PLATON (Spek, 2009).C16H18O4 | Dx = 1.204 Mg m−3 |
Mr = 274.30 | Melting point: 353 K |
Monoclinic, P21 | Mo Kα radiation, λ = 0.71073 Å |
a = 10.4566 (2) Å | Cell parameters from 4503 reflections |
b = 5.9821 (1) Å | θ = 2.8–27.1° |
c = 12.2040 (3) Å | µ = 0.09 mm−1 |
β = 97.460 (1)° | T = 296 K |
V = 756.93 (3) Å3 | Prism, colourless |
Z = 2 | 0.18 × 0.16 × 0.10 mm |
F(000) = 292 |
Bruker SMART CCD area detector diffractometer | 2956 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.022 |
Graphite monochromator | θmax = 31.3°, θmin = 1.7° |
φ and ω scans | h = −14→13 |
9344 measured reflections | k = −8→8 |
4067 independent reflections | l = −17→15 |
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.042 | H-atom parameters constrained |
wR(F2) = 0.122 | w = 1/[σ2(Fo2) + (0.0573P)2 + 0.0653P] where P = (Fo2 + 2Fc2)/3 |
S = 1.05 | (Δ/σ)max < 0.001 |
4067 reflections | Δρmax = 0.17 e Å−3 |
181 parameters | Δρmin = −0.18 e Å−3 |
1 restraint | Absolute structure: Flack x determined using 1007 quotients [(I+)-(I-)]/[(I+)+(I-)] (Parsons et al., 2013) |
Primary atom site location: structure-invariant direct methods | Absolute structure parameter: 0.3 (4) |
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. |
x | y | z | Uiso*/Ueq | ||
O1 | 0.12555 (13) | 0.2273 (3) | 0.39523 (11) | 0.0489 (4) | |
O2 | 0.50752 (14) | 0.2713 (4) | 0.37581 (15) | 0.0755 (6) | |
O3 | 0.3243 (2) | 0.3359 (4) | 0.10399 (14) | 0.0881 (8) | |
O4 | 0.40770 (18) | 0.6100 (4) | 0.21193 (13) | 0.0752 (6) | |
C1 | −0.0461 (2) | 0.2348 (5) | 0.20244 (19) | 0.0561 (5) | |
H1 | −0.0462 | 0.1011 | 0.2413 | 0.067* | |
C2 | −0.1503 (2) | 0.2900 (6) | 0.1253 (2) | 0.0729 (8) | |
H2 | −0.2191 | 0.1912 | 0.1111 | 0.087* | |
C3 | −0.1528 (3) | 0.4892 (5) | 0.0698 (2) | 0.0674 (7) | |
H3 | −0.2235 | 0.5261 | 0.0187 | 0.081* | |
C4 | −0.0512 (3) | 0.6335 (5) | 0.08947 (19) | 0.0627 (6) | |
H4 | −0.0532 | 0.7691 | 0.0520 | 0.075* | |
C5 | 0.0551 (2) | 0.5787 (4) | 0.16510 (18) | 0.0541 (5) | |
H5 | 0.1244 | 0.6769 | 0.1777 | 0.065* | |
C6 | 0.05799 (18) | 0.3777 (4) | 0.22179 (15) | 0.0424 (4) | |
C7 | 0.16819 (18) | 0.3149 (4) | 0.30515 (15) | 0.0423 (4) | |
C8 | 0.2174 (2) | 0.1069 (4) | 0.47652 (17) | 0.0530 (5) | |
C9 | 0.3435 (2) | 0.2362 (4) | 0.49400 (17) | 0.0528 (5) | |
H9A | 0.3300 | 0.3770 | 0.5302 | 0.063* | |
H9B | 0.4070 | 0.1512 | 0.5420 | 0.063* | |
C10 | 0.3938 (2) | 0.2810 (4) | 0.38704 (18) | 0.0521 (5) | |
C11 | 0.29465 (19) | 0.3414 (4) | 0.29526 (16) | 0.0459 (5) | |
C12 | 0.3405 (2) | 0.4251 (5) | 0.19222 (17) | 0.0547 (6) | |
C13 | 0.4738 (3) | 0.6981 (8) | 0.1238 (2) | 0.0963 (13) | |
H13A | 0.5113 | 0.5760 | 0.0865 | 0.116* | |
H13B | 0.4125 | 0.7746 | 0.0701 | 0.116* | |
C14 | 0.5723 (3) | 0.8489 (8) | 0.1667 (3) | 0.1034 (13) | |
H14A | 0.6150 | 0.9056 | 0.1075 | 0.155* | |
H14B | 0.5349 | 0.9707 | 0.2027 | 0.155* | |
H14C | 0.6336 | 0.7725 | 0.2191 | 0.155* | |
C15 | 0.2348 (3) | −0.1253 (5) | 0.4300 (3) | 0.0783 (9) | |
H15A | 0.2942 | −0.2090 | 0.4808 | 0.117* | |
H15B | 0.1531 | −0.2007 | 0.4192 | 0.117* | |
H15C | 0.2681 | −0.1128 | 0.3605 | 0.117* | |
C16 | 0.1518 (3) | 0.1011 (8) | 0.5791 (2) | 0.0875 (10) | |
H16A | 0.2058 | 0.0246 | 0.6369 | 0.131* | |
H16B | 0.1367 | 0.2511 | 0.6023 | 0.131* | |
H16C | 0.0710 | 0.0239 | 0.5638 | 0.131* |
U11 | U22 | U33 | U12 | U13 | U23 | |
O1 | 0.0441 (7) | 0.0547 (9) | 0.0467 (7) | 0.0023 (7) | 0.0011 (6) | 0.0116 (7) |
O2 | 0.0423 (8) | 0.1023 (16) | 0.0785 (11) | −0.0052 (10) | −0.0048 (7) | −0.0141 (11) |
O3 | 0.0995 (14) | 0.115 (2) | 0.0519 (9) | −0.0407 (14) | 0.0162 (9) | −0.0276 (11) |
O4 | 0.0920 (13) | 0.0859 (14) | 0.0504 (8) | −0.0423 (12) | 0.0197 (8) | −0.0099 (9) |
C1 | 0.0504 (11) | 0.0567 (14) | 0.0589 (12) | −0.0055 (11) | −0.0020 (9) | 0.0120 (11) |
C2 | 0.0513 (12) | 0.080 (2) | 0.0815 (17) | −0.0104 (13) | −0.0140 (11) | 0.0144 (16) |
C3 | 0.0580 (13) | 0.0758 (19) | 0.0637 (14) | 0.0122 (13) | −0.0104 (11) | 0.0126 (13) |
C4 | 0.0772 (16) | 0.0557 (15) | 0.0529 (12) | 0.0123 (13) | −0.0002 (11) | 0.0138 (11) |
C5 | 0.0625 (12) | 0.0468 (13) | 0.0516 (11) | −0.0038 (11) | 0.0021 (9) | 0.0065 (10) |
C6 | 0.0434 (10) | 0.0437 (11) | 0.0397 (9) | 0.0029 (9) | 0.0035 (7) | 0.0003 (8) |
C7 | 0.0465 (10) | 0.0401 (11) | 0.0396 (9) | −0.0008 (9) | 0.0027 (7) | −0.0020 (8) |
C8 | 0.0549 (11) | 0.0503 (13) | 0.0498 (10) | −0.0030 (11) | −0.0086 (9) | 0.0126 (10) |
C9 | 0.0562 (11) | 0.0478 (12) | 0.0495 (11) | −0.0008 (11) | −0.0115 (9) | −0.0011 (10) |
C10 | 0.0460 (10) | 0.0511 (14) | 0.0565 (11) | −0.0084 (10) | −0.0042 (9) | −0.0112 (11) |
C11 | 0.0448 (10) | 0.0484 (13) | 0.0437 (9) | −0.0061 (9) | 0.0024 (8) | −0.0055 (9) |
C12 | 0.0472 (11) | 0.0685 (17) | 0.0479 (11) | −0.0093 (11) | 0.0042 (9) | −0.0089 (11) |
C13 | 0.097 (2) | 0.142 (4) | 0.0517 (13) | −0.052 (2) | 0.0141 (13) | 0.0076 (17) |
C14 | 0.106 (2) | 0.127 (3) | 0.0813 (19) | −0.042 (2) | 0.0285 (18) | 0.006 (2) |
C15 | 0.0798 (17) | 0.0445 (14) | 0.100 (2) | −0.0041 (13) | −0.0282 (16) | 0.0054 (14) |
C16 | 0.0816 (17) | 0.122 (3) | 0.0569 (14) | −0.016 (2) | 0.0003 (12) | 0.0320 (17) |
O1—C7 | 1.345 (2) | C8—C9 | 1.519 (3) |
O1—C8 | 1.476 (2) | C8—C15 | 1.521 (4) |
O2—C10 | 1.216 (2) | C9—C10 | 1.493 (3) |
O3—C12 | 1.194 (3) | C9—H9A | 0.9700 |
O4—C12 | 1.316 (3) | C9—H9B | 0.9700 |
O4—C13 | 1.452 (3) | C10—C11 | 1.469 (3) |
C1—C6 | 1.380 (3) | C11—C12 | 1.489 (3) |
C1—C2 | 1.384 (3) | C13—C14 | 1.417 (5) |
C1—H1 | 0.9300 | C13—H13A | 0.9700 |
C2—C3 | 1.369 (4) | C13—H13B | 0.9700 |
C2—H2 | 0.9300 | C14—H14A | 0.9600 |
C3—C4 | 1.366 (4) | C14—H14B | 0.9600 |
C3—H3 | 0.9300 | C14—H14C | 0.9600 |
C4—C5 | 1.389 (3) | C15—H15A | 0.9600 |
C4—H4 | 0.9300 | C15—H15B | 0.9600 |
C5—C6 | 1.386 (3) | C15—H15C | 0.9600 |
C5—H5 | 0.9300 | C16—H16A | 0.9600 |
C6—C7 | 1.483 (3) | C16—H16B | 0.9600 |
C7—C11 | 1.353 (3) | C16—H16C | 0.9600 |
C8—C16 | 1.505 (3) | ||
C7—O1—C8 | 118.91 (15) | H9A—C9—H9B | 108.0 |
C12—O4—C13 | 117.7 (2) | O2—C10—C11 | 122.0 (2) |
C6—C1—C2 | 120.2 (2) | O2—C10—C9 | 123.4 (2) |
C6—C1—H1 | 119.9 | C11—C10—C9 | 114.65 (17) |
C2—C1—H1 | 119.9 | C7—C11—C10 | 120.29 (18) |
C3—C2—C1 | 120.4 (3) | C7—C11—C12 | 122.69 (18) |
C3—C2—H2 | 119.8 | C10—C11—C12 | 117.00 (17) |
C1—C2—H2 | 119.8 | O3—C12—O4 | 123.4 (2) |
C4—C3—C2 | 119.9 (2) | O3—C12—C11 | 126.0 (2) |
C4—C3—H3 | 120.0 | O4—C12—C11 | 110.56 (18) |
C2—C3—H3 | 120.0 | C14—C13—O4 | 110.5 (2) |
C3—C4—C5 | 120.3 (2) | C14—C13—H13A | 109.6 |
C3—C4—H4 | 119.8 | O4—C13—H13A | 109.6 |
C5—C4—H4 | 119.8 | C14—C13—H13B | 109.6 |
C6—C5—C4 | 120.0 (2) | O4—C13—H13B | 109.6 |
C6—C5—H5 | 120.0 | H13A—C13—H13B | 108.1 |
C4—C5—H5 | 120.0 | C13—C14—H14A | 109.5 |
C1—C6—C5 | 119.12 (19) | C13—C14—H14B | 109.5 |
C1—C6—C7 | 119.06 (19) | H14A—C14—H14B | 109.5 |
C5—C6—C7 | 121.8 (2) | C13—C14—H14C | 109.5 |
O1—C7—C11 | 123.38 (17) | H14A—C14—H14C | 109.5 |
O1—C7—C6 | 110.42 (15) | H14B—C14—H14C | 109.5 |
C11—C7—C6 | 126.20 (17) | C8—C15—H15A | 109.5 |
O1—C8—C16 | 104.07 (19) | C8—C15—H15B | 109.5 |
O1—C8—C9 | 108.85 (18) | H15A—C15—H15B | 109.5 |
C16—C8—C9 | 112.1 (2) | C8—C15—H15C | 109.5 |
O1—C8—C15 | 107.07 (18) | H15A—C15—H15C | 109.5 |
C16—C8—C15 | 112.3 (3) | H15B—C15—H15C | 109.5 |
C9—C8—C15 | 112.0 (2) | C8—C16—H16A | 109.5 |
C10—C9—C8 | 111.47 (17) | C8—C16—H16B | 109.5 |
C10—C9—H9A | 109.3 | H16A—C16—H16B | 109.5 |
C8—C9—H9A | 109.3 | C8—C16—H16C | 109.5 |
C10—C9—H9B | 109.3 | H16A—C16—H16C | 109.5 |
C8—C9—H9B | 109.3 | H16B—C16—H16C | 109.5 |
C6—C1—C2—C3 | −1.8 (4) | C15—C8—C9—C10 | 64.4 (3) |
C1—C2—C3—C4 | 0.8 (4) | C8—C9—C10—O2 | −140.8 (3) |
C2—C3—C4—C5 | 0.4 (4) | C8—C9—C10—C11 | 40.0 (3) |
C3—C4—C5—C6 | −0.6 (4) | O1—C7—C11—C10 | −2.2 (3) |
C2—C1—C6—C5 | 1.6 (4) | C6—C7—C11—C10 | 177.1 (2) |
C2—C1—C6—C7 | 179.8 (2) | O1—C7—C11—C12 | 176.0 (2) |
C4—C5—C6—C1 | −0.4 (3) | C6—C7—C11—C12 | −4.7 (3) |
C4—C5—C6—C7 | −178.6 (2) | O2—C10—C11—C7 | 169.0 (2) |
C8—O1—C7—C11 | −14.6 (3) | C9—C10—C11—C7 | −11.7 (3) |
C8—O1—C7—C6 | 165.99 (18) | O2—C10—C11—C12 | −9.3 (4) |
C1—C6—C7—O1 | −42.0 (3) | C9—C10—C11—C12 | 169.9 (2) |
C5—C6—C7—O1 | 136.1 (2) | C13—O4—C12—O3 | −5.2 (4) |
C1—C6—C7—C11 | 138.6 (2) | C13—O4—C12—C11 | 172.1 (3) |
C5—C6—C7—C11 | −43.3 (3) | C7—C11—C12—O3 | −62.4 (4) |
C7—O1—C8—C16 | 161.9 (2) | C10—C11—C12—O3 | 115.9 (3) |
C7—O1—C8—C9 | 42.2 (3) | C7—C11—C12—O4 | 120.3 (2) |
C7—O1—C8—C15 | −79.0 (2) | C10—C11—C12—O4 | −61.4 (3) |
O1—C8—C9—C10 | −53.7 (3) | C12—O4—C13—C14 | −161.2 (3) |
C16—C8—C9—C10 | −168.3 (3) |
D—H···A | D—H | H···A | D···A | D—H···A |
C9—H9B···O2i | 0.97 | 2.60 | 3.470 (3) | 150 |
C15—H15A···O2i | 0.96 | 2.54 | 3.406 (3) | 151 |
Symmetry code: (i) −x+1, y−1/2, −z+1. |
Acknowledgements
NS thanks Professor A. Ilangovan, School of Chemistry, Bharathidasan University, Tiruchirappalli, Tamilnadu, India, for kind help with the data collection.
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