Synthesis and Crystal Structures of Two New Oxaspirocyclic Compounds
MicroScale Science Institute, Department of Chemistry, Chemical Engineering and Environmental Engineering, Weifang University, Weifang 261061, China
*
Author to whom correspondence should be addressed.
Crystals 2016, 6(10), 134; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst6100134
Submission received: 3 August 2016
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Revised: 19 September 2016
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Accepted: 6 October 2016
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Published: 18 October 2016
Abstract
:Two new oxaspirocyclic compounds, 8-(4-(dimethylamino)benzylidene)-6,10-dioxaspiro[4.5]decane-7,9-dione (1) and 8-(4-hydroxybenzylidene)-6,10-dioxaspiro[4.5]decane-7,9-dione (2) have been synthesized and their structures determined by single crystal X-ray crystallography. Compound 1, C17H19NO4, belongs to the monoclinic system, space group P21/c with a = 6.2554(13) Å, b = 14.605(3) Å, c = 16.265(3) Å, β = 95.97(3)°, V = 1477.9(5) Å3, Z = 4, Dc = 1.354 g/cm3, F(000) = 640, μ(MoKa) = 0.097 mm−1, the final R = 0.0570 and wR = 0.1667. Compound 2, C15H14O5, is also of the monoclinic system, space group P21/c with a = 10.739(2) Å, b = 18.348(4) Å, c = 6.7799(14) Å, β = 104.20(3)°, V = 1295.1(5) Å3, Z = 4, Dc = 1.407 g/cm3, F(000) = 608, μ(MoKa) = 0.106 mm−1, the final R = 0.0568 and wR = 0.1739. Some C–H···O intra- and intermolecular hydrogen bonds and π··· π stacking interactions are both observed in the two lattice structures. The difference between them is that one type of C–H···π supramolecular interaction (1) and one type of O–H···O intermolecular hydrogen bond (2) are observed.
1. Introduction
In recent years, many efforts have been devoted to the preparation and characterization of spiro compounds due to diverse industrial and biomedical applications in medicine [1,2,3], catalysis [4], 18F-radiolabeling [5] and optical material [6,7,8]. The asymmetric characteristic of the molecules, owing to the chiral spiro carbon, is one of the important criteria of the biological activities. Also, it has been found that the selectivities and activities of spiro compounds will be stronger by inducting an oxygen atom. The presence of oxaspirocyclic compounds in various natural products has also emerged, increasing interest due to their important biological activities, such as antimicrobial [9,10], antitumor [11] ,antiproliferative [12], antiviral [13], antiplasmodial [14] and antihistamic [15] activity etc. Based on these reasons, our group began to synthesize various oxaspirocyclic compounds and study their chemical properties [16,17,18,19]. In addition, to the best of our knowledge, oxaspirocyclic compounds derived from 6,10-dioxaspiro[4.5]decane-7,9-dione are very rare. In this paper, we describe the synthesis of two new oxaspirocyclic compounds: 8-(4-(dimethylamino) benzylidene)-6,10-dioxaspiro[4.5] decane-7,9-dione 1 and -6,10-dioxaspiro[4.5]decane-7,9-dione 2. Their structures are also characterized by elemental analysis, IR, NMR and single-crystal X-ray diffraction.
2. Results and Discussion
2.1. Crystal Structures
Selected bond lengths and angles of the two compounds are listed in Table 1. The molecular structures of 1 and 2 are shown in Figure 1. The packing arrangements in the unit cell of 1 and 2 are illustrated in Figure 2, respectively.
The two compounds both consist of a phenyl ring and 6,10-dioxaspiro[4.5]decane-7,9-dione group which connects a five-membered cyclopentane ring with the other O-containing six-membered ring by a C spiro atom (Figure 1). The selected bond lengths and bond angles of compound 1 are similar to those of 2 correspondingly.
As can be seen from the Table 1, the C(7)–C(9)–C(15) bond angle of 137.76(2)° (1), 129.67(2)° (2) is likewise in agreement with those reported earlier (136.78(18)°, 136.5(2)°) [18]. The C9–C7 bond length of 1.373(3) Å (1), 1.356(3) Å (2) is indicative of the considerable double-bond character, while the C9–C15 bond length of 1.428(3) Å (1), 1.447(3) Å (2) is the typical C–C single bond. The 1,3-dioxane rings of the two compounds are both in a distorted envelope conformation with atom C(1), common to the cyclopentane ring forming the flap. It is noteworthy that the cyclopentane rings of the two compounds exhibit a different configuration. The cyclopentane ring of 1 is in half-chair configuration with puckering parameters [20] for q2 = 0.335(4) Å, ϕ2 = 96.3(6)°; while the cyclopentane ring in 2 exhibits an envelope configuration with puckering parameters for q2 = 0.298 Å, ϕ2 = 55.14°.
In 1, all atoms in the 4-dimethylamino benzylidene group are fairly planar (Plane equation: 2.469x + 4.909y + 13.165z = 10.899), with the maximum deviation from the mean plane of 0.069(3) Å. The four atoms—O2, O3, C6 and C7—form a plane (Plane equation: 2.047x + 2.929y + 14.384z = 10.021), with the largest deviation of 0.014(3) Å. The dihedral angle between the two planes is 9.53°. In 2, all atoms in the 4-hydroxybenzylidene group are also quite planar, (Plane equation: –2.6309x − 0.2671y + 6.7792z = 1.0129), and the largest deviation from the least squares plane is 0.035(3) Å. The four atoms—O4, O1 C6 and C7—form a plane (Plane equation: –5.2019x + 2.6946y + 6.4742z = 0.4529), with no deviation. The dihedral angle between the two planes is 17.71°.
The two compounds have a similar structure. There are π···π stacking interactions and some C−H···O intra- and intermolecular hydrogen bonds in the two lattice structures. In addition, one type of C−H···π supramolecular interaction in 1 is also present. One classical intermolecular hydrogen bond of O−H···O is also observed in 2 (Table 2 and Table 3). All above hydrogen bonds and intermolecular interactions play a significant role in stabilizing the crystal structures (Figure 3).
2.2. IR Spectra
The IR spectra of the two compounds show a little difference. The broad absorptions at 3265 cm−1 for 2 are assigned to the O–H stretching vibration of PhOH. The strong bands at 1705 cm−1 1 and 1745 cm−1 2, respectively, are due to the C=O stretching vibration of the 1,3-dioxane ring. The broad absorptions at 1167 cm−1, 1126 cm−1 for 1 and at 1204 cm−1, 1163 cm−1 for 2 are assigned to the C–O stretching vibration of the 1,3-dioxane ring. Meanwhile, a similar band at 1609 cm−1 and 1688 cm−1 was observed in the IR spectra of 1 and 2, respectively, indicting C=C stretching vibration of N(CH3)2−ph−C=C in 1 and HO−ph−C=C in 2. The IR spectra of the two compounds are in agreement with the structural data.
3. Experimental Section
3.1. Materials and Methods
All the reagents and solvents from commercial sources were used without further purification. The IR spectra were recorded as KBr pellets with a Nicolet FT-IR 510P Spectrometer (Nicolet Instrument Inc., Madison, WI, USA). The analyses of C, H, and N were made on an Elementar Vario EL III elemental analyzer (Elementar, Hanau, Germany). 1H NMR spectra were recorded on a Bruker Avance-400 spectrometer (Bruker, Elisabethhof, The Netherlands) with CH3COCH3 as the solvent. Melting points were measured by using a melting point apparatus made in Shanghai Instrument Limited Company. The X-ray single-crystal data collection for the compounds 1 and 2 were performed on a Bruker Smart-1000 CCD diffractometer.
3.2. Preparation of Two Oxaspirocyclic Compounds
The synthetic route is shown in Scheme 1.
The mixture of malonic acid (6.24 g, 0.06 mol) and acetic anhydride (9 mL) in strong sulfuric acid (0.25 mL) was stirred with a water bath at 303K. After dissolving, cyclopentanone (5.04 g, 0.06 mol) was added dropwise into the solution for 2 h. The reaction was allowed to proceed for 3 h. Then the mixture was cooled, washed with water and filtered. The intermediate compound, 6,10-dioxaspiro [4.5]decane-7,9-dione, was obtained. 4-(dimethylamino)benzaldehyde (1.49 g, 0.01 mol) was added to the ethanol solution (20 mL) containing 6,10-dioxaspiro[4.5]decane-7,9-dione (1.70 g, 0.01 mol). Then the mixture was stirred and refluxed for 3 h. After cooling to room temperature, the precipitate was filtered off and dried. Yield 36%, m.p.: 162.6～163.1 °C. Anal. Calcd. for C17H19NO4: C, 67.76; H, 6.36; N, 4.65. Found: C, 67.68; H, 6.28; N, 4.78. 1H NMR (ppm): 8.20 (d, 2H, Ar–H), 8.17 (s, 1H, =CH–), 6.80 (d, 2H, Ar–H), 3.2 (s, 6H, N–(CH3)2), 2.15 (m, 4H, cyclopentane–H), 1.84 (s, 4H, cyclopentane–H). The red single crystals of 1 were obtained by evaporation of a solution in petroleum ether and ethyl acetate (2:1 = v/v) after a few days.
The synthesis procedure of 2 was similar to that of 1, except that 4-(dimethylamino)benzaldehyde was replaced by 4-hydroxybenzaldehyde (1.22 g, 0.01 mol). Yield 36%, m.p.: 164.6～165.2 °C. Anal. Calcd. for C15H14O5: C, 65.69; H, 5.15; Found: C, 65.53; H, 5.08. 1H NMR (ppm): 9.66 (s, 1H, –OH), 8.15 (s, 1H, =CH–) 8.22–8.24 (m, 2H, Ar–H), 6.99–7.0 (d, 2H, Ar–H), 2.19 (s, 4H, cyclopentane–H), 1.86 (s, 4H, cyclopentane–H). The yellow crystals suitable for X-ray diffraction analysis were obtained by slow evaporation of a solution in petroleum ether and ethyl acetate (1:1 = v/v).
3.3. Crystallography
The structures of two compounds were solved by direct methods and refined by full-matrix least-squares techniques on F2 using SHELXS-97 and SHELXL-97 programs [21]. The non-hydrogen atoms were refined anisotropically. All hydrogen atoms were positioned with idealized geometry and were refined isotropic with an Uiso(H) = 1.2Ueq(C) of the corresponding parent atom using a riding model. The contributions of hydrogen atoms were included in the structure-factor calculations. The atomic scattering factors and anomalous dispersion corrections were taken from International Table for X-ray Crystallography [22]. The final cycle of refinement gave R = 0.0570 and wR = 0.1667 (R = 0.0568 and wR = 0.1739 for 2) with w = 1/(σ2(Fo2) + (0.0995 P)2 + 0.4137 P) (w = 1/(σ2(Fo2) + (0.0937P)2 + 0.5137 P) for 2), where P = (Fo2 + 2Fc2)/3. Crystallographic data are summarized in Table 4. CCDC-1486129 (2) and CCDC-1486130 (1) contain the supplementary crystallographic data for this paper. These data can be obtained free of charge from the CCDC, 12 Union Road, Cambridge CB2 1EZ, UK; Fax: +44 1223 336033; E-mail: [email protected].
4. Conclusions
Two new oxaspirocyclic spiro compounds, 8-(4-(dimethylamino)benzylidene)-6,10-dioxaspiro[4.5] decane-7,9-dione (1) and 8-(4-hydroxybenzylidene)-6,10-dioxaspiro[4.5]decane-7,9-dione (2), have been synthesized and characterized by elemental analysis, IR and single-crystal X-ray diffraction. Some C−H···O intra- and intermolecular hydrogen bonds and π··· π stacking interactions are both observed in the two lattice structures. The difference between them is that one type of C–H···π supramolecular interaction (1) and one type of O−H···O intermolecular hydrogen bond (2) are observed.
Supplementary Materials
The following are available online at https://0-www-mdpi-com.brum.beds.ac.uk/2073-4352/6/10/134/s1. cif 1: the cif file of compound 1; cif 2: the cif file of compound 2.
Acknowledgements
This project was supported by the National Natural Science Foundation of China (No. 51541205), the Project of Shandong Province Higher Educational Science and Technology Program (No. J11LC62) and the Development Plan of Science and Technology of Weifang.
Author Contributions
Jinhe Jiang synthesized compound 1 and compound 2. Wulan Zeng conceived and designed the experiments and wrote the paper.
Conflicts of Interest
The authors confirm that this article content has no conflict of interest.
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Figure 1.
The molecular structures of 1 and 2 with the atomic numbering scheme.
Figure 2.
The packing arrangement in a unit cell of 1 and 2.
Figure 3.
Hydrogen bonds and intermolecular interactions of 1 and 2.
Scheme 1.
Synthesis of two new oxaspirocyclic compounds.
| Compound 1 | Compound 2 | ||
|---|---|---|---|
| O(1)−C(8) | 1.367(3) | O(2)−C(8) | 1.353(3) |
| O(1)−C(1) | 1.422(3) | O(2)−C(1) | 1.423(3) |
| C(9)−C(7) | 1.373(3) | C(7)−C(9) | 1.356(3) |
| C(15)−C(9) | 1.428(3) | C(9)−C(10) | 1.447(3) |
| O(3)−C(6) | 1.201(3) | O(4)−C(6) | 1.214(3) |
| O(4)−C(8) | 1.202(3) | O(3)−C(8) | 1.202(3) |
| O(2)−C(6) | 1.360(3) | O(1)−C(6) | 1.339(2) |
| O(2)−C(1) | 1.415(3) | O(1)−C(1) | 1.454(3) |
| C(12)−N(1) | 1.362(3) | O(5)−C(12) | 1.355(3) |
| N(1)−C(16) | 1.446(3) | C(10)−C(15) | 1.399(3) |
| N(1)−C(17) | 1.448(3) | C(7)–C(6) | 1.475(3) |
| C(7)−C(9)−C(15) | 137.76(2) | C(7)−C(9)−C(15) | 129.67(2) |
| C(2)−C(1)−C(5) | 106.3(2) | C(2)−C(1)−C(5) | 106.3(2) |
| O(2)−C(1)−O(1) | 109.63(2) | O(2)−C(1)−O(1) | 108.55(2) |
| C(6)−C(7)−C(8) | 117.6(2) | C(6)−C(7)−C(8) | 115.54(2) |
| C(10)−C(15)−C(14) | 115.4(2) | C(10)−C(15)−C(14) | 117.61(2) |
| C(10)−C(15)−C(9) | 116.42(2) | C(10)−C(15)−C(9) | 119.42(19) |
Table 2.
Intra- and intermolecular hydrogen bonds and C–H···π supramolecular interactions in 1 and 2.
| D−H···A | Symmetry | D−H(Å) | H···A(Å) | D···A(Å) | ∠D−H···A (°) |
|---|---|---|---|---|---|
| C(9)−H(9A)···O(4) (1) | intra | 0.93(2) | 2.357(3) | 2.795(3) | 108.5(2) |
| C(14)−H(14A)···O(3) (1) | intra | 0.93(2) | 2.116(2) | 2.900(3) | 141.1(3) |
| C(17)−H(17A)···O(4) (1) | 1 – x, 1 – y, 1 – z | 0.96(3) | 2.558(2) | 3.466(3) | 157.7(19) |
| C(9)−H(9A)···O(4) (2) | intra | 0.93(2) | 2.489(2) | 2.846(2) | 102.9(2) |
| C(14)−H(14A)···O(3) (2) | intra | 0.93(2) | 2.535(3) | 3.008(2) | 111.8(2) |
| C(9)−H(9A)···O(3) (2) | x, 1/2 – y, –1/2 + z | 0.93(2) | 2.539(2) | 3.458(3) | 169.8(19) |
| O(5)−H(5A)···O(4) (2) | 1 + x, 1/2 – y, 1/2 + z | 0.82(2) | 1.976(2) | 2.707(2) | 148.0(3) |
| C(3)−H(3B)···Cg(3) (1) | 1/2 – x, 1/2 + y, 3/2 – z | 0.97(3) | 3.127(2) | 3.832(2) | 130.8(2) |
Cg(3) ring denotes the phenyl ring of compound 1: C(10)–C(15).
| Ring | Symmetry | Dihedral Angels (°) | Distance Between Ring Centroids (Å) | Perpendicular Distance of Cg(I) on Ring J(Å) | Perpendicular Distance of Cg(J) on Ring I(Å) |
|---|---|---|---|---|---|
| Cg(3)··· Cg(3) a (1) | –x, 1 – y, 1 – z | 0.02(2) | 5.112(3) | 3.691(2) | 3.691(2) |
| Cg(3)··· Cg(3) b (2) | x, 1/2 – y, –1/2 + z | 1.89(2) | 4.048(2) | 3.353(2) | 3.426(3) |
| Cg(3)··· Cg(3) b (2) | x, 1/2 – y ,1/2 + z | 1.89(2) | 4.048(2) | 3.426(3) | 3.353(2) |
a Cg(3) ring denotes the phenyl ring of compound 1: C(10)–C(15); b Cg(3) ring denotes the phenyl ring of compound 2: C(10)–C(15).
| Compounds | 1 | 2 |
|---|---|---|
| CCDC No. | 1486130 | 1486129 |
| Empirical formula | C17H19NO4 | C15H14O5 |
| Color/shape | red/block | yellow/block |
| Formula weight | 301.33 | 274.26 |
| Crystal system | Monoclinic | Monoclinic |
| Space group | P21/n | P21/c |
| Unit cell dimensions | a = 6.2554(13) Å, α = 90° b = 14.605(3) Å, β = 95.97(3)° c = 16.265(3)Å, γ = 90° | a = 10.739(2) Å, α = 90° b = 18.348(4) Å, β = 104.20(3)° c = 6.7799(14) Å, γ = 90° |
| Volume/Å3 | 1477.9(5) | 1295.1(5) |
| Z | 4 | 4 |
| Dx/g cm−3 | 1.354 | 1.407 |
| μ/mm−1 | 0.097 | 0.106 |
| F(000) | 640 | 608 |
| Crystal size/mm3 | 0.25 × 0.18 × 0.12 | 0.18 × 0.12 × 0.10 |
| θmin/θmax/° | 3.06/27.48 | 3.29/27.48 |
| Limiting indices | –7 ≤ h ≤ 8, –18 ≤ k ≤ 18, –21 ≤ l ≤ 21 | –13 ≤ h ≤ 13, –23 ≤ k ≤ 23, –8 ≤ l ≤ 7 |
| Reflections collected | 14232 | 11961 |
| Independent reflections | 3370 [R(int) = 0.0330] | 2964 [R(int) = 0.0360] |
| Reflections observed(I>2σ(I)) | 2184 | 2286 |
| Refinement method | Full-matrix least-squares on F2 | Full-matrix least-squares on F2 |
| Data/restraints/parameters | 3370/0/199 | 2964/0/181 |
| Goodness-of-fit on F2 | 1.146 | 1.112 |
| R1/wR2(I>2σ(I)) R1/wR2(all data) | 0.0570/0.1667 0.0866/0.2009 | 0.0568/0.1739 0.0711/0.1869 |
| ∆ρmax/∆ρmin/e Å−3 | 0.389/–0.318 | 0.763/–0.380 |
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MDPI and ACS Style
Jiang, J.; Zeng, W. Synthesis and Crystal Structures of Two New Oxaspirocyclic Compounds. Crystals 2016, 6, 134. https://0-doi-org.brum.beds.ac.uk/10.3390/cryst6100134
AMA Style
Jiang J, Zeng W. Synthesis and Crystal Structures of Two New Oxaspirocyclic Compounds. Crystals. 2016; 6(10):134. https://0-doi-org.brum.beds.ac.uk/10.3390/cryst6100134
Chicago/Turabian StyleJiang, Jinhe, and Wulan Zeng. 2016. "Synthesis and Crystal Structures of Two New Oxaspirocyclic Compounds" Crystals 6, no. 10: 134. https://0-doi-org.brum.beds.ac.uk/10.3390/cryst6100134
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