research communications
E)-furan-2-carbaldehyde O-benzoyloxime
of (aDepartment of Chemistry and Earth Sciences, Qatar University, PO Box 2713, Doha, Qatar, and bQatar Environment and Energy Research Institute, Hamad Bin Khalifa University, Qatar Foundation, PO Box 34110, Doha, Qatar
*Correspondence e-mail: yousef.hijji@qu.edu.qa, hyahia@qf.org.qa
In the title compound, C12H9NO3, the benzoate and furan rings are almost coplanar, making a dihedral angle of 11.68 (9)°. The twist angle between the –COO group and the benzene ring is only 2.79 (16)°. In the crystal, molecules are linked by C—H⋯O hydrogen bonds, forming chains along [100]. The molecules stack in a herringbone fashion and inversion-related chains are linked by offset π–π interactions [intercentroid distance = 3.931 (1) Å], forming ribbons propagating along the a-axis direction.
Keywords: crystal structure; oxime; 2-furanaldoxime; benzoyloxime ester; hydrogen bonding.
CCDC reference: 1549733
1. Chemical context
Oxime et al., 2013, 2006). These compounds are good antioxidants and are used in pharmaceutical compositions for their anti-microbial activity (Liu et al., 2008; Harini et al., 2012; Ahluwalia et al., 2017). In view of this interest, we have synthesized the title oxime ester derivative and report herein on its crystal structure.
have shown potencies for inhibiting lipoprotein-associated phospholipase A2 (Lp-PLA2) activity. Their derivatives are used for the prevention and treatment of cardiovascular disease (Jeong2. Structural commentary
The molecular structure of the title compound is shown in Fig. 1. An intramolecular short contact (C8—H8⋯O2) is present (Table 1), which may prevent the –COO group from tilting, since the twist angle between the –C6/O2/O3 unit and the benzene ring (C7–C12) is only 2.79 (16)°. This also might be the reason why the molecule is almost planar. The dihedral angle between the furan (O1/C1–C4) ring and the benzene ring is 11.68 (9)°. The C6—O2 and C6=O3 distances of 1.352 (2) and 1.195 (2) Å, respectively, are typical values for single and double C-O bonds. This overall geometry is very similar to that observed for E-benzaldehyde O-benzoyloxime (Altinbas et al., 2004). Within the five-membered furan ring, the interatomic O1—C1 and O1—C4 distances of 1.369 (2) and 1.367 (2) Å, respectively, are typical values for O—Csp2 bonds. The short C4—C3 and C1—C2 bond lengths of 1.324 (4) and 1.347 (3) Å, respectively, and the stretched C2—C3 bond distance of 1.408 (2) Å are typical values observed for double C=C and single C—C bonds, respectively. The –C5/N1/O2 group is twisted by 4.40 (13) ° with respect to the furan ring. The N1—O2 distance of 1.444 (1) Å is only slightly longer than reported in other oxime compounds (Wetherington & Moncrief, 1973), whereas the C=N—O angle of 106.73 (11)° is slightly smaller.
3. Supramolecular features
In the crystal, molecules are linked by C—H⋯O hydrogen bonds, forming chains along the a-axis direction (Table 1 and Fig. 2). The molecules stack in a herringbone fashion and inversion-related chains are linked by offset π–π interactions [Cg1⋯Cg1i = 3.931 (1) Å, interplanar distance = 3.574 (1) Å, slippage = 1.64 Å, α = 0.03 (7)°, Cg1 is the centroid of the benzene ring (C7–C12); symmetry code: (i) −x + 1, −y + 2, −z], forming ribbons propagating along the a-axis direction (Fig. 3).
4. Database survey
A search of the Cambridge Structural Database (Version 5.38, update May 2017; Groom et al., 2016) for the furan-2-carbaldehyde oxime gave 20 hits, while for formaldehyde O-benzoyloxime there were 24 hits. The O—N distances vary from ca 1.38 to 1.45 Å, while the N=C distances vary from ca 1.25 to 1.32 Å. In the title compound, these distances are N1—O2 = 1.444 (1) Å and N1=C5 is 1.270 (2) Å, within the limits observed. In the majority of the formaldehyde O-benzoyloxime structures, the dihedral angle between the plane of the –COO group and the benzene ring is <10 °. In the title compound, this dihedral angle is 2.79 (16)°.
5. Synthesis and crystallization
Synthesis of 2-furanaldoxime: A mixture of 5.0 g of furfuraldehyde (without further purification), 1.5 equiv. of NH2OH·HCl and 1 mmol of pyridine was stirred for 3 h at rt until the NH2OH·HCl was completely solubilized. The reaction mixture was then quenched in water and the furanaldoxime precipitated out. This solid was filtered and recrystallized from diethyl ether to give colourless needle-like crystals (yield 4.268 g, 74%; m.p. 349–351 K). FT–IR spectrum showed two peaks at 3166 and 1634 cm−1. Elemental analysis: analysis calculated for C5H5NO2 (111.10 g mol−1): C, 54.05; H, 4.54; N, 12.61; O, 28.80%. Found: C, 53.13; H, 4.45; N, 12.99; O, 29.43%. 1H NMR (DMSO-d6): δ (ppm): 6.64 (dd, J = 3.42Hz, 0.49 Hz, 1H), 7.20 (d, J = 3.42Hz, 1H), 7.52 (s, 1H), 7.76 (s, 1H), 11.80 (s, 1H). 13C NMR (DMSO-d6): δ (ppm) = 145.85, 143.80, 135.92, 116.89, 112.67.
Preparation of the O-benzoyl ester of furanaldoxime: Benzoyl chloride (5.01 mmol) was added dropwise under stirring to 4.55 mmol of furanaldoxime. Since the reaction was vigorous and exothermic the mixture was placed in an ice bath for 30 min. The reaction mixture was then quenched in ice–water, and then extracted with EtOAc. The organic layer was separated and washed with 1M NaOH solution to remove the benzoic acid and HCl that had formed as by products. The EtOAc layer was passed through anhydrous Na2SO4 and dried in vacuo to give the title compound as a light-brown solid (0.9806 g). Recrystallization of the title compound from ethanol–EtOAc gave colourless needle-like crystals (yield 50%, m.p. 410–412 K). Elemental analysis: analysis calculated for C12H9NO3 (215.20 g mol−1): C, 66.97; H, 4.22; N, 6.51; O, 22.30%. Found: C, 67.00; H, 4.19; N, 6.40; O, 22.41%. 1H NMR (DMSO-d6): δ (ppm): 6.74–6.75 (dd, J = 3.67Hz,1.96Hz, 1H), 7.18 (d, J = 3.42Hz, 1H), 7.60 (t, J = 8.04 Hz, 2H), 7.73 (t, J = 7.58Hz, 1H), 8.01 (s, 1H), 8.07 (dd, J = 8.56 Hz,1.22 Hz 2H), 8.82 (s, 1H). 13C NMR (DMSO-d6): δ ppm: 163.55, 148.05, 147.65, 145.28, 134.35, 129.77, 129.48, 128.52, 119.14, 113.07.
6. Refinement
Crystal data, data collection and structure . The H atoms were located from difference-Fourier maps and freely refined.
details are summarized in Table 2Supporting information
CCDC reference: 1549733
https://doi.org/10.1107/S2056989017011562/gw2156sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2056989017011562/gw2156Isup2.hkl
Supporting information file. DOI: https://doi.org/10.1107/S2056989017011562/gw2156Isup3.cml
Data collection: APEX3 (Bruker, 2015); cell
SAINT (Bruker, 2015); data reduction: SAINT (Bruker, 2015); program(s) used to solve structure: SIR2002 (Burla et al. 2003); program(s) used to refine structure: JANA2006 (Petricek et al., 2014); molecular graphics: DIAMOND (Brandenburg & Berndt, 1999) and Mercury (Macrae et al., 2008); software used to prepare material for publication: JANA2006 (Petricek et al., 2014).C12H9NO3 | F(000) = 448 |
Mr = 215.2 | Dx = 1.368 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71069 Å |
Hall symbol: -P 2ybc | Cell parameters from 19019 reflections |
a = 6.3414 (3) Å | θ = 2.3–27.9° |
b = 9.1268 (5) Å | µ = 0.1 mm−1 |
c = 18.1423 (9) Å | T = 293 K |
β = 95.634 (2)° | Needle, colourless |
V = 1044.94 (9) Å3 | 0.19 × 0.06 × 0.04 mm |
Z = 4 |
D8 venture diffractometer | 1245 reflections with I > 3σ(I) |
Radiation source: X-ray tube | Rint = 0.061 |
ω and π scans | θmax = 27.9°, θmin = 2.3° |
Absorption correction: multi-scan (SADABS; Bruker, 2015) | h = −7→8 |
Tmin = 0.87, Tmax = 0.89 | k = −12→12 |
19019 measured reflections | l = −23→23 |
2480 independent reflections |
Refinement on F2 | All H-atom parameters refined |
R[F > 3σ(F)] = 0.037 | Weighting scheme based on measured s.u.'s w = 1/(σ2(I) + 0.001936I2) |
wR(F) = 0.101 | (Δ/σ)max = 0.002 |
S = 1.05 | Δρmax = 0.24 e Å−3 |
2480 reflections | Δρmin = −0.19 e Å−3 |
182 parameters | Extinction correction: B–C type 1 Gaussian isotropic (Becker & Coppens, 1974) |
0 restraints | Extinction coefficient: 8600 (1100) |
0 constraints |
x | y | z | Uiso*/Ueq | ||
O1 | 0.30081 (17) | 0.35070 (10) | 0.20660 (6) | 0.0583 (4) | |
O2 | 0.40886 (16) | 0.65844 (10) | 0.04205 (5) | 0.0509 (4) | |
O3 | 0.76174 (18) | 0.66965 (13) | 0.06946 (6) | 0.0708 (5) | |
N1 | 0.4062 (2) | 0.55510 (12) | 0.10223 (6) | 0.0514 (5) | |
C1 | 0.1492 (3) | 0.42685 (14) | 0.16340 (8) | 0.0476 (5) | |
C2 | −0.0453 (3) | 0.39050 (16) | 0.18114 (10) | 0.0599 (7) | |
H2 | −0.177 (3) | 0.4294 (17) | 0.1589 (9) | 0.071 (5)* | |
C3 | −0.0152 (4) | 0.28632 (18) | 0.23844 (10) | 0.0695 (8) | |
H3 | −0.120 (3) | 0.2372 (18) | 0.2617 (9) | 0.076 (5)* | |
C4 | 0.1916 (4) | 0.26537 (18) | 0.25172 (10) | 0.0682 (8) | |
H4 | 0.279 (3) | 0.2027 (17) | 0.2837 (9) | 0.074 (5)* | |
C5 | 0.2128 (3) | 0.52772 (15) | 0.10928 (8) | 0.0468 (5) | |
H5 | 0.099 (3) | 0.5716 (15) | 0.0768 (8) | 0.060 (4)* | |
C6 | 0.6056 (2) | 0.70645 (15) | 0.03182 (8) | 0.0448 (5) | |
C7 | 0.6002 (2) | 0.81086 (13) | −0.03072 (7) | 0.0402 (5) | |
C8 | 0.4156 (3) | 0.84781 (16) | −0.07375 (8) | 0.0505 (6) | |
H8 | 0.290 (2) | 0.8040 (15) | −0.0630 (7) | 0.058 (4)* | |
C9 | 0.4214 (3) | 0.94724 (17) | −0.13070 (10) | 0.0600 (7) | |
H9 | 0.295 (3) | 0.9700 (17) | −0.1605 (9) | 0.073 (5)* | |
C10 | 0.6096 (3) | 1.01023 (18) | −0.14491 (9) | 0.0596 (7) | |
H10 | 0.617 (3) | 1.0760 (16) | −0.1852 (9) | 0.069 (5)* | |
C11 | 0.7926 (3) | 0.97388 (18) | −0.10261 (9) | 0.0619 (7) | |
H11 | 0.922 (3) | 1.0175 (17) | −0.1118 (9) | 0.072 (5)* | |
C12 | 0.7884 (3) | 0.87486 (17) | −0.04569 (9) | 0.0521 (6) | |
H12 | 0.917 (3) | 0.8530 (15) | −0.0176 (9) | 0.067 (5)* |
U11 | U22 | U33 | U12 | U13 | U23 | |
O1 | 0.0656 (9) | 0.0566 (6) | 0.0511 (6) | −0.0020 (5) | −0.0023 (5) | 0.0048 (5) |
O2 | 0.0418 (7) | 0.0557 (6) | 0.0551 (6) | 0.0011 (5) | 0.0037 (5) | 0.0127 (5) |
O3 | 0.0408 (8) | 0.0946 (8) | 0.0751 (8) | 0.0062 (6) | −0.0033 (6) | 0.0227 (6) |
N1 | 0.0521 (10) | 0.0499 (7) | 0.0518 (8) | 0.0018 (6) | 0.0026 (6) | 0.0090 (6) |
C1 | 0.0539 (11) | 0.0431 (7) | 0.0458 (9) | 0.0023 (7) | 0.0056 (7) | −0.0043 (6) |
C2 | 0.0589 (13) | 0.0498 (9) | 0.0740 (11) | 0.0015 (8) | 0.0217 (10) | 0.0002 (8) |
C3 | 0.0903 (18) | 0.0522 (9) | 0.0718 (12) | −0.0055 (10) | 0.0368 (12) | −0.0006 (9) |
C4 | 0.1016 (19) | 0.0539 (10) | 0.0491 (11) | −0.0050 (11) | 0.0081 (10) | 0.0044 (8) |
C5 | 0.0443 (11) | 0.0464 (8) | 0.0498 (9) | 0.0024 (7) | 0.0052 (7) | −0.0011 (7) |
C6 | 0.0350 (10) | 0.0488 (7) | 0.0506 (9) | 0.0034 (6) | 0.0043 (7) | −0.0060 (7) |
C7 | 0.0347 (9) | 0.0416 (7) | 0.0447 (8) | 0.0012 (6) | 0.0061 (6) | −0.0067 (6) |
C8 | 0.0385 (11) | 0.0556 (8) | 0.0577 (10) | −0.0016 (7) | 0.0067 (8) | 0.0046 (8) |
C9 | 0.0482 (13) | 0.0682 (10) | 0.0627 (11) | 0.0040 (8) | 0.0019 (9) | 0.0134 (8) |
C10 | 0.0586 (13) | 0.0624 (10) | 0.0592 (11) | −0.0018 (9) | 0.0134 (9) | 0.0103 (8) |
C11 | 0.0516 (13) | 0.0694 (10) | 0.0668 (11) | −0.0138 (9) | 0.0171 (9) | 0.0000 (9) |
C12 | 0.0373 (11) | 0.0643 (9) | 0.0544 (10) | −0.0023 (8) | 0.0032 (8) | −0.0035 (8) |
O1—C1 | 1.3688 (17) | C5—H5 | 0.970 (15) |
O1—C4 | 1.367 (2) | C6—C7 | 1.4795 (19) |
O2—N1 | 1.4441 (14) | C7—C8 | 1.383 (2) |
O2—C6 | 1.3523 (19) | C7—C12 | 1.379 (2) |
O3—C6 | 1.1945 (18) | C8—H8 | 0.927 (16) |
N1—C5 | 1.270 (2) | C8—C9 | 1.378 (2) |
C1—C2 | 1.347 (3) | C9—H9 | 0.944 (17) |
C1—C5 | 1.433 (2) | C9—C10 | 1.372 (3) |
C2—H2 | 0.957 (17) | C10—H10 | 0.950 (16) |
C2—C3 | 1.408 (2) | C10—C11 | 1.368 (2) |
C3—H3 | 0.936 (18) | C11—H11 | 0.943 (17) |
C3—C4 | 1.324 (4) | C11—C12 | 1.374 (2) |
C4—H4 | 0.952 (16) | C12—H12 | 0.941 (16) |
C1—O1—C4 | 105.29 (14) | O3—C6—C7 | 125.11 (14) |
N1—O2—C6 | 113.27 (10) | C6—C7—C8 | 122.99 (13) |
O2—N1—C5 | 106.73 (11) | C6—C7—C12 | 117.92 (13) |
O1—C1—C2 | 110.27 (13) | C8—C7—C12 | 119.09 (13) |
O1—C1—C5 | 119.30 (14) | C7—C8—H8 | 118.1 (8) |
C2—C1—C5 | 130.42 (15) | C7—C8—C9 | 120.00 (15) |
C1—C2—H2 | 126.0 (10) | H8—C8—C9 | 121.9 (9) |
C1—C2—C3 | 106.37 (18) | C8—C9—H9 | 119.4 (10) |
H2—C2—C3 | 127.6 (10) | C8—C9—C10 | 120.31 (16) |
C2—C3—H3 | 127.2 (10) | H9—C9—C10 | 120.2 (10) |
C2—C3—C4 | 107.0 (2) | C9—C10—H10 | 121.1 (10) |
H3—C3—C4 | 125.7 (10) | C9—C10—C11 | 119.92 (16) |
O1—C4—C3 | 111.09 (16) | H10—C10—C11 | 118.9 (10) |
O1—C4—H4 | 114.1 (11) | C10—C11—H11 | 120.3 (9) |
C3—C4—H4 | 134.8 (11) | C10—C11—C12 | 120.21 (17) |
N1—C5—C1 | 122.35 (14) | H11—C11—C12 | 119.5 (10) |
N1—C5—H5 | 121.6 (9) | C7—C12—C11 | 120.48 (15) |
C1—C5—H5 | 116.0 (9) | C7—C12—H12 | 121.7 (10) |
O2—C6—O3 | 123.68 (13) | C11—C12—H12 | 117.8 (10) |
O2—C6—C7 | 111.21 (12) |
D—H···A | D—H | H···A | D···A | D—H···A |
C8—H8···O2 | 0.93 (2) | 2.384 (13) | 2.724 (2) | 102 (1) |
C5—H5···O3i | 0.97 (2) | 2.312 (16) | 3.159 (2) | 145 (1) |
Symmetry code: (i) x−1, y, z. |
Acknowledgements
We are grateful to Mr Ahmed Abdelsalam Ali Easa of the Central Laboratory Unit, Qatar University, for the elemental analysis, and to Mr Ziad Sarah from the American University of Sharjah for measuring the NMR data.
Funding information
Funding for this research was provided by: Qatar National Research Fund (award No. NPRP-7-495-1-094).
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