research communications
of 1,2-bis(4-fluorophenyl)-1-hydroxy-2,3,8-trimethoxyacenaphthene: formation of a five-membered intramolecular O—H⋯O hydrogen-bonded ring
aDepartment of Organic and Polymer Materials Chemistry, Tokyo University of Agriculture & Technology (TUAT), Koganei, Tokyo 184-8588, Japan
*Correspondence e-mail: aokamoto@cc.tuat.ac.jp
The structure of the title compound, C27H22F2O4, at 193 K has triclinic (P) symmetry. The hydroxy and methoxy groups at the 1,2-positions of the acenaphthene core display a cis configuration. Both substituents are involved in the formation of a five-membered intramolecular O—H⋯O hydrogen-bonded ring. The 4-fluorophenyl rings make dihedral angles of 87.02 (7) and 51.86 (8)° with the naphthalene ring system. In the crystal, a pair of non-classical C—H⋯O hydrogen bonds forms centrosymmetric dimeric structures. The dimeric aggregates are linked in the ac plane through non-classical C—H⋯F hydrogen bonds and C—H⋯π interactions.
Keywords: acenaphthene; asymmetric molecular structure; cis-configuration; intramolecular O—H⋯O hydrogen bond; crystal structure.
CCDC reference: 2057372
1. Chemical context
The chemistry of congested aromatic-ring-accumulation compounds has attracted continuous interest, especially in non-classical non-covalent bonding interactions other than classical hydrogen bonds. Steric factors of these compounds influenced by the presence of exocyclic bonds presumably bring about in-plane and/or out-of-plane deviations from the ordinary geometry of aromatic molecules. Consequently, the molecules undergo geometrical changes to release the strain in the molecular skeleton, which, in turn, modulates the π-electron delocalization. These space–structural characteristics result in an alteration of the reactivity and properties of the near-by moiety of the molecule (Tannaci et al., 2007; Pascal, 2006; Downing et al., 1994; Biedermann et al., 2001). From the point of view of such structural properties, the authors have been investigating peri-substituted naphthalene and 1,2-disubstituted acenaphthene compounds, focusing on the molecular structure and packing of the above compounds and their analogues and homologues along with the reaction behaviour, including the formation reaction and the design of novel categories of highly performing and functional organic and polymer materials (Okamoto & Yonezawa, 2015).
The authors have found that peri-aroylnaphthalene compounds are selectively yielded via electrophilic aromatic diaroylation of a naphthalene derivative in the presence of a suitable acidic mediator (Okamoto & Yonezawa, 2009; Okamoto et al., 2011). In peri-aroylnaphthalene compounds, probably caused by the aroyl groups tend to be arranged nearly perpendicular relative to the core naphthalene plane. Bearing this in mind, the authors have continued their crystallographic study of homologous and analogous peri-aroylnaphthalene compounds for elucidation of the correlation between molecular structure, crystal packing and non-covalent bonding interactions. As one of the readily performable reactions of peri-aroylnaphthalene compounds, a Zn-mediated reductive coupling to 1,2-diaryl-1,2-acenaphthenediol has been discovered (Mido et al., 2017, 2020). Herein, the of 1,2-bis(4-fluorophenyl)-1-hydroxy-2,3,8-trimethoxyacenaphthene (I), a monoalkoxylated derivative of a pinacol-coupling product, is reported and its structural features are discussed through comparison with homologues.
2. Structural commentary
The molecular structure of the title compound is shown in Fig. 1. This compound consists of an acenaphthene ring system core with a hydroxy group and a 4-fluorophenyl group at the 1-position, a methoxy group and a 4-fluorophenyl group at the 2-position, and two methoxy groups at the 3- and 8-positions. In the title compound, the two 4-fluorophenyl groups at the 1,2-positions are located on the same side of the acenaphthene ring system plane (i.e. cis), and the 1-hydroxy and 2-methoxy groups are positioned on the other side. Moreover, the hydrogen atom of the hydroxy group at the 1-position is located in between the two oxygen atoms (O3 and O4) of the hydroxy and the methoxy groups at the 1,2-positions, with the methyl group oriented away. A puckering analysis (Cremer & Pople, 1975; Luger & Bülow, 1983) suggests that the five-membered ring of the acenaphthene core has a half-chair conformation. The positions of the ring substituents can be described as bisectional for the hydroxy group at the 1-position, axial for the 4-fluorophenyl group at the 1-position, axial for the methoxy group at the 2-position, and bisectional for the 4-fluorophenyl group at the 2-position (Fig. 2). The two benzene rings of the 4-fluorophenyl groups are twisted out of the naphthalene plane (C1–C10) of the acenaphthene ring system. The C19–C24 benzene ring at the 1-position is more heavily tilted compared to the C12–C17 benzene ring at the 2-position, as indicated by the dihedral angles of the best planes through the benzene rings and naphthalene ring system, which are 87.02 (7) and 51.86 (8)°, respectively. The dihedral angle between the two benzene rings is 43.47 (9)°. Furthermore, the C12—C11—C18—C19 torsion angle [31.37 (15)°] indicates a large slippage between the two benzene rings. In addition, the five-membered ring C1,C9,C8,C18,C11 and the naphthalene ring system (C1–C10) are not coplanar, the dihedral angle between their best planes being 7.03 (7)°.
An intramolecular classical O—H⋯O hydrogen bond forming a five-membered cyclic arrangement is observed between hydroxy group O4—H4 and oxygen atom O3 of the methoxy group at the 1- and the 2-positions of the acenaphthene ring system (see Table 1). An intramolecular C—H⋯π interaction between hydrogen atom H24 of one of the 4-fluorophenyl groups and the acenaphthene ring system is also observed (C24—H24⋯Cg9 = 2.90 Å; Cg9 is the centroid of the acenaphthene ring; see also Table 1). The possibility of intramolecular classical O—H⋯O hydrogen bond formation as part of a five-membered cyclic arrangement in 1,2-acenaphthenediol was proposed several decades ago by infrared spectroscopy (Moriconi et al., 1959; Hayward & Csizmadia, 1963). Trotter and Mak have designed and synthesized cis-1,2-acenaphthenediol (Trotter & Mak, 1963). However, in the of the pinacol compound, no effective intramolecular interactions were observed. Instead, intermolecular O—H⋯O interactions align the molecules sequentially to form a chain-like structure in the crystal packing and the formation of intermolecular O—H⋯O hydrogen bonds took precedence over an intramolecular classical O—H⋯O hydrogen bond. In contrast, in the title compound, the hydroxy and methoxy groups are presumably forced to form an intramolecular hydrogen bond, i.e., the spatial arrangement of the two benzene rings – probably restricted by the methoxy groups at the 3,8-positions – inhibits the approach of other molecules.
3. Supramolecular features
In the molecular packing, a pair of non-classical C—H⋯O hydrogen bonds between hydrogen H20 of a 4-fluorophenyl group (2-positioned) and oxygen O4 of the hydroxy group at the 1-position of the acenaphthene unit connects two molecules of the title compound, forming a centrosymmetric dimer [C20—H20⋯O4i, 2.49 Å; symmetry code: (i) −x, 1 − y, 1 − z] (Table 1, Fig. 3). The dimers are arranged along the c axis through non-classical C—H⋯F hydrogen bonds between hydrogen atom H4A at the 5-position of the acenaphthene unit and fluorine atom F1 of the 4-fluorophenyl group at the 2-position of the acenaphthene ring system [C4—H4A⋯F1, 2.44 Å; symmetry code: (ii) x, y, 1 + z] (Table 1, Fig. 4). In addition, three non-classical C—H⋯π hydrogen bonds between the methoxy group at the 8-position and the acenaphthene unit [C26—H26C⋯Cg2iii, 2.70 Å; C26—H26C⋯Cg8iii, 2.85Å; C26—H26C⋯Cg9iii, 2.91 Å; symmetry code: (iii) −x, −y + 1, −z + 2; Cg2 and Cg8 are the centroids of the rings (C1–C4,C9,C10) and (C1–C10), respectively] (Fig. 4). The dimer chains are linked by non-classical C—H⋯π hydrogen bonds along the a-axis direction [C25—H25B⋯Cg5iv, 2.81 Å; symmetry code: (iv) x + 1, y, z; Cg5 is the centroid of ring (C19–C24)] (Fig. 4).
The asymmetric molecular structure, with only one of the hydroxy groups methoxylated, disrupts the spatial alignment observed when both hydroxy groups interact with adjacent molecules, forming chain structures (Trotter & Mak, 1963). Instead of the stabilization energy obtained by forming a chain structure, the title molecules afford the centrosymmetric dimer as the packing motif. The intramolecular classical O—H⋯OMe hydrogen bond is required to adjust the spatial arrangement for forming centrosymmetric dimers. The non-classical hydrogen-bonding interactions connecting the dimeric aggregates contribute to further stabilize the molecular packing.
4. Database survey
A search of the Cambridge Structural Database (CSD version 5.41, last update August 2020; Groom et al., 2016) for the 1,2-disubstituted acenaphthene moiety of the title compound yielded 27 hits. These include compounds with a 1,2-acenaphthenediol moiety and a similar 1,2-diaryl-1,2-acenaphthenediol unit. A search for 1,2-acenaphthenediol and its derivatives gave 18 hits (CSD refcode FILQAV: Tao et al., 2018; FILQEZ: Tao et al., 2018; GACWUE: Maghsoodlou et al. 2009; QIBMIX: Parvez et al. 2001; HERPIG and HERPOM: Sato et al., 2017; REWGEG: Jimenez et al., 2007; ROCBIU: Plater et al., 1997; TESDIE: Nair et al., 2000; UYENET, UYENIX and UYENIX01: Joussot et al., 2016; UYENET01: Joussot et al., 2017; YIMRIY: Myhill et al., 2018).
The title compound has a cis-configuration. For 1,2-acenaphthenediol and its derivatives, cis- and trans-configurations are found for 1,2-acenaphthenediol and its dinitrates (ACNAOL: Trotter et al., 1963; ZZZPKU and ZZZIWC: Mak et al., 1963; ANADON: Mak et al., 1964).
A search with a 1,2-diaryl-1,2-acenaphthenediol framework gave nine hits. Among these, three reports are for 1,2-diphenyl-1,2-acenaphthenediol and its et al., 2000). In addition we found 1,2-bis(1′-naphthyl)-1,2-acenaphthenediol (MOKZUH: Guo et al., 2000), 1,2-bis(4-tolyl)-1,2-acenaphthenediol (CIZTIO: Gatilov et al., 1984) and 1,2-bis(4-methoxyphenyl)-1,2-acenaphthenediol (QARGEW and QATQAE: Suzuki et al., 2005). Most 1,2-diaryl-1,2-acenaphthenediol derivatives have a trans-configuration, except for one example (MOKZUH). In contrast to the title molecule, these 1,2-diaryl-1,2-acenaphthenediol derivatives have a highly symmetric spatial structure, e.g., the two phenyl groups make dihedral angles with the naphthalene ring system of 85.42 and 82.93° for CIZTIO, 57.05 and 56.83° for QARGEW, 64.18 and 66.06° for QATQAE vs 87.02 (7) and 51.86 (8)° for the title compound. The phenyl rings at the 1,2-positions in these analogues are tilted 20 to 30° from each other, i.e., 22.49° for CIZTIO, 25.88° for QARGEW and 28.10° for QATQAE vs 43.47 (9)° for the title compound.
(MOKZER, MOKZIV and MOKZOB: GuoThere are only two reports on 1,2-diaryl-1,2-acenaphthene derivatives with both hydroxy groups protected, i.e., (S,S,S,S)-1,2-bis(4-methoxyphenyl)acenaphthene-1,2-diyl bis(2-isopropyl-5-methylcyclohexyl) bis(carbonate) (QARGIA: Suzuki et al., 2005) and 1,2-(benzyloxy)-1,2-bis(4-chlorophenyl)-3,8-dimethoxyacenaphthene (AZOPEL: Takada et al., 2011). The carbonate analogue (QARGIA) is more similar to 1,2-diaryl-1,2-acenaphthenediol than the title compound, with the dihedral angles between the 4-methoxyphenyl rings and the naphthalene ring system being 60.97 and 54.14° and a dihedral angle between the 4-methoxyphenyl rings of 27.17°. The benzyl-protected analogue (AZOPEL) has two similarities with the title compound. First, the spatial arrangement of the 4-phenyl rings with respect to the naphthalene ring system with similar dihedral angles between the 4-chlorophenyl rings and the naphthalene unit [85.74 (6) and 57.12 (6)° for AZOPEL, 87.02 (7) and 51.86 (8)° for the title compound]. In addition, the formation of centrosymmetric dimers connected by non-classical C—H⋯π hydrogen bonds is observed in the crystal packing.
No reports were found for 1,2-diaryl-1,2-acenaphthene homologues with one hydroxy group protected.
5. Synthesis and crystallization
1,2-Bis(4-fluorophenyl)-1-hydroxy-2,3,8-trimethoxyacenaphthene (0.25 mmol, 108.6 mg), K2CO3 (0.25 mmol, 34.55 mg), iodomethane (0.25 mmol, 35.49 mg) and DMF (0.5 mL) were placed in a 10 mL flask. The reaction mixture was stirred at room temperature for 10 h and then poured into iced water (20 mL). The solution was extracted with CHCl3 and successively washed with 2 M aqueous HCl and brine. The organic layers thus obtained were dried over anhydrous MgSO4. After removal of solvent under reduced pressure, the crude product was obtained (quant.). The cake was crystallized from methanol to give single crystals (isolated yield 64%), m.p. 432–434 K.
1H NMR (CDCl3, 300 MHz) δ 3.22 (s, 3H), 3.73 (s, 3H), 3.79 (s, 3H), 5.05 (s, 1H), 6.48 (dd, 4H, J = 8.40, 8.40 Hz), 6.73 (broad, 4H), 7.21 (d, 1H, J = 8.70 Hz), 7.24 (d, 1H, J = 9.00 Hz), 7.82 (d, 1H, J = 9.00 Hz), 7.88 (d, 1H, J = 9.00 Hz) ppm.
13C NMR (CDCl3, 75 MHz) δ 161.92 (JC–F = 243 Hz), 161.54 (JC–F = 243 Hz), 155.03, 154.46, 141.32, 138.85 (JC–F = 2.90 Hz), 133.05 (JC–F = 2.90 Hz), 128.51, 128.21 (JC–F = 7.88 Hz), 127.20, 127.14 (JC–F = 9.30 Hz), 121.93, 119.67, 114.75, 113.79 (JC–F = 20.7 Hz), 113.67 (JC–F = 22.2 Hz), 113.23, 93.365, 90.248, 56.537, 55.677, 53.440 ppm.
IR (KBr) ν 3488, 2838, 1627, 1601, 1506, 1269, 1224, 1159, 1073, 1048 cm−1.
6. Refinement
Crystal data, data collection and structure . All H atoms were located in a difference-Fourier map and were subsequently refined as riding on their carriers, with C—H = 0.95 Å (aromatic) and Uiso(H) = 1.2 Ueq(C). Hydrogen atom O4 was refined freely.
details are summarized in Table 2
|
Supporting information
CCDC reference: 2057372
https://doi.org/10.1107/S2056989021000669/vm2244sup1.cif
contains datablock I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2056989021000669/vm2244Isup2.hkl
IR spectrum of title compound. DOI: https://doi.org/10.1107/S2056989021000669/vm2244sup3.pdf
NMR spectrum (-0.5-10.5 ppm). DOI: https://doi.org/10.1107/S2056989021000669/vm2244sup4.pdf
NMR spectrum (3.0-4.0 ppm). DOI: https://doi.org/10.1107/S2056989021000669/vm2244sup5.pdf
NMR spectrum (6.0-8.0 ppm). DOI: https://doi.org/10.1107/S2056989021000669/vm2244sup6.pdf
Supporting information file. DOI: https://doi.org/10.1107/S2056989021000669/vm2244Isup7.cml
Data collection: PROCESS-AUTO (Rigaku, 1998); cell
PROCESS-AUTO (Rigaku, 1998); data reduction: CrystalStructure (Rigaku, 2010); program(s) used to solve structure: SIR2014 (Burla et al., 2007); program(s) used to refine structure: SHELXL2018/3 (Sheldrick, 2015); molecular graphics: OLEX2 (Dolomanov et al., 2009); software used to prepare material for publication: OLEX2 (Dolomanov et al., 2009).C27H22F2O4 | Z = 2 |
Mr = 448.44 | F(000) = 468 |
Triclinic, P1 | Dx = 1.371 Mg m−3 |
a = 10.14886 (18) Å | Cu Kα radiation, λ = 1.54187 Å |
b = 11.1827 (2) Å | Cell parameters from 15130 reflections |
c = 11.6411 (2) Å | θ = 4.1–68.2° |
α = 66.724 (1)° | µ = 0.86 mm−1 |
β = 77.693 (1)° | T = 193 K |
γ = 63.613 (1)° | Plate, colourless |
V = 1086.07 (4) Å3 | 0.8 × 0.35 × 0.1 mm |
Rigaku R-AXIS RAPID diffractometer | 3743 reflections with I > 2σ(I) |
Detector resolution: 10.00 pixels mm-1 | Rint = 0.063 |
ω scans | θmax = 68.2°, θmin = 4.1° |
Absorption correction: numerical (NUMABS; Higashi, 1999) | h = −11→12 |
Tmin = 0.542, Tmax = 0.918 | k = −13→13 |
40472 measured reflections | l = −13→14 |
3919 independent reflections |
Refinement on F2 | Hydrogen site location: mixed |
Least-squares matrix: full | H atoms treated by a mixture of independent and constrained refinement |
R[F2 > 2σ(F2)] = 0.043 | w = 1/[σ2(Fo2) + (0.0586P)2 + 0.398P] where P = (Fo2 + 2Fc2)/3 |
wR(F2) = 0.115 | (Δ/σ)max < 0.001 |
S = 1.06 | Δρmax = 0.32 e Å−3 |
3919 reflections | Δρmin = −0.21 e Å−3 |
306 parameters | Extinction correction: SHELXL2018/3 (Sheldrick 2015), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
0 restraints | Extinction coefficient: 0.0290 (13) |
Primary atom site location: structure-invariant direct methods |
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 | ||
F1 | 0.54395 (13) | 0.19439 (16) | 0.30239 (12) | 0.0761 (4) | |
F2 | 0.10156 (14) | −0.08720 (11) | 0.63826 (10) | 0.0606 (3) | |
O1 | 0.58174 (13) | 0.24840 (15) | 0.78038 (13) | 0.0578 (4) | |
O2 | −0.16964 (13) | 0.39006 (15) | 0.92690 (12) | 0.0557 (3) | |
O3 | 0.21992 (11) | 0.51843 (10) | 0.68218 (9) | 0.0355 (3) | |
O4 | −0.00974 (11) | 0.48709 (11) | 0.68032 (9) | 0.0355 (3) | |
C1 | 0.33402 (16) | 0.28835 (15) | 0.83979 (13) | 0.0348 (3) | |
C2 | 0.47642 (18) | 0.23756 (17) | 0.87338 (17) | 0.0443 (4) | |
C3 | 0.5048 (2) | 0.18063 (19) | 1.00327 (19) | 0.0563 (5) | |
H3 | 0.603535 | 0.140640 | 1.026987 | 0.068* | |
C4 | 0.3953 (2) | 0.18154 (19) | 1.09462 (17) | 0.0547 (5) | |
H4A | 0.418739 | 0.145106 | 1.179868 | 0.066* | |
C5 | 0.1206 (2) | 0.25049 (19) | 1.14585 (15) | 0.0533 (5) | |
H5 | 0.130872 | 0.221041 | 1.233168 | 0.064* | |
C6 | −0.0160 (2) | 0.30589 (19) | 1.10192 (15) | 0.0504 (4) | |
H6 | −0.099321 | 0.317931 | 1.158771 | 0.060* | |
C7 | −0.03631 (18) | 0.34594 (17) | 0.97319 (14) | 0.0410 (4) | |
C8 | 0.08404 (16) | 0.33506 (14) | 0.89067 (13) | 0.0325 (3) | |
C9 | 0.22314 (17) | 0.28432 (15) | 0.93596 (13) | 0.0352 (3) | |
C10 | 0.2480 (2) | 0.23577 (16) | 1.06408 (14) | 0.0451 (4) | |
C11 | 0.25998 (15) | 0.36839 (14) | 0.71479 (13) | 0.0298 (3) | |
C12 | 0.33911 (15) | 0.32035 (15) | 0.60487 (13) | 0.0315 (3) | |
C13 | 0.44715 (17) | 0.18364 (16) | 0.62201 (15) | 0.0389 (3) | |
H13 | 0.473777 | 0.119168 | 0.704339 | 0.047* | |
C14 | 0.51608 (18) | 0.14074 (19) | 0.52049 (18) | 0.0483 (4) | |
H14 | 0.591121 | 0.048181 | 0.532017 | 0.058* | |
C15 | 0.47354 (18) | 0.2349 (2) | 0.40290 (17) | 0.0498 (4) | |
C16 | 0.36465 (19) | 0.3690 (2) | 0.38148 (15) | 0.0475 (4) | |
H16 | 0.335172 | 0.430894 | 0.299057 | 0.057* | |
C17 | 0.29898 (16) | 0.41139 (17) | 0.48419 (14) | 0.0382 (3) | |
H17 | 0.225034 | 0.504644 | 0.471534 | 0.046* | |
C18 | 0.09992 (14) | 0.35988 (14) | 0.75182 (12) | 0.0293 (3) | |
C19 | 0.09615 (14) | 0.23884 (14) | 0.72425 (12) | 0.0289 (3) | |
C20 | 0.06485 (16) | 0.26136 (15) | 0.60484 (13) | 0.0343 (3) | |
H20 | 0.042476 | 0.352859 | 0.542456 | 0.041* | |
C21 | 0.06587 (18) | 0.15193 (17) | 0.57558 (14) | 0.0403 (4) | |
H21 | 0.044205 | 0.167574 | 0.494082 | 0.048* | |
C22 | 0.09894 (18) | 0.02068 (16) | 0.66732 (15) | 0.0411 (4) | |
C23 | 0.12865 (18) | −0.00576 (16) | 0.78620 (15) | 0.0428 (4) | |
H23 | 0.149917 | −0.097429 | 0.848094 | 0.051* | |
C24 | 0.12699 (16) | 0.10486 (15) | 0.81439 (13) | 0.0356 (3) | |
H24 | 0.147274 | 0.088352 | 0.896580 | 0.043* | |
C25 | 0.7328 (2) | 0.1777 (3) | 0.8115 (3) | 0.0758 (7) | |
H25A | 0.751122 | 0.222033 | 0.860643 | 0.091* | |
H25B | 0.795464 | 0.185182 | 0.734481 | 0.091* | |
H25C | 0.755334 | 0.077256 | 0.860669 | 0.091* | |
C26 | −0.2991 (2) | 0.4337 (2) | 1.00169 (19) | 0.0586 (5) | |
H26A | −0.304348 | 0.350782 | 1.072245 | 0.070* | |
H26B | −0.385404 | 0.478465 | 0.951198 | 0.070* | |
H26C | −0.297245 | 0.502043 | 1.033444 | 0.070* | |
C27 | 0.33921 (18) | 0.56172 (17) | 0.65522 (16) | 0.0439 (4) | |
H27A | 0.393886 | 0.521162 | 0.730991 | 0.053* | |
H27B | 0.300590 | 0.665657 | 0.626704 | 0.053* | |
H27C | 0.405055 | 0.528052 | 0.589461 | 0.053* | |
H4 | 0.010 (3) | 0.553 (3) | 0.677 (2) | 0.068 (7)* |
U11 | U22 | U33 | U12 | U13 | U23 | |
F1 | 0.0604 (7) | 0.1262 (11) | 0.0743 (8) | −0.0387 (7) | 0.0184 (6) | −0.0758 (8) |
F2 | 0.0874 (8) | 0.0489 (6) | 0.0625 (6) | −0.0347 (6) | −0.0005 (6) | −0.0285 (5) |
O1 | 0.0283 (6) | 0.0732 (8) | 0.0771 (9) | −0.0168 (6) | −0.0053 (6) | −0.0335 (7) |
O2 | 0.0382 (7) | 0.0851 (9) | 0.0588 (7) | −0.0323 (6) | 0.0186 (5) | −0.0413 (7) |
O3 | 0.0335 (5) | 0.0294 (5) | 0.0434 (6) | −0.0157 (4) | 0.0060 (4) | −0.0127 (4) |
O4 | 0.0296 (5) | 0.0296 (5) | 0.0409 (6) | −0.0073 (4) | −0.0062 (4) | −0.0086 (4) |
C1 | 0.0348 (8) | 0.0331 (7) | 0.0382 (8) | −0.0130 (6) | −0.0062 (6) | −0.0124 (6) |
C2 | 0.0350 (8) | 0.0431 (8) | 0.0583 (10) | −0.0117 (7) | −0.0108 (7) | −0.0209 (7) |
C3 | 0.0528 (11) | 0.0467 (9) | 0.0707 (12) | −0.0089 (8) | −0.0329 (9) | −0.0188 (8) |
C4 | 0.0758 (13) | 0.0452 (9) | 0.0445 (9) | −0.0216 (9) | −0.0256 (9) | −0.0084 (7) |
C5 | 0.0902 (14) | 0.0503 (10) | 0.0277 (7) | −0.0393 (10) | 0.0033 (8) | −0.0118 (7) |
C6 | 0.0710 (12) | 0.0550 (10) | 0.0382 (8) | −0.0397 (9) | 0.0172 (8) | −0.0222 (7) |
C7 | 0.0479 (9) | 0.0438 (8) | 0.0409 (8) | −0.0272 (7) | 0.0111 (7) | −0.0203 (7) |
C8 | 0.0371 (8) | 0.0320 (7) | 0.0318 (7) | −0.0181 (6) | 0.0022 (6) | −0.0113 (5) |
C9 | 0.0440 (8) | 0.0304 (7) | 0.0334 (7) | −0.0175 (6) | −0.0037 (6) | −0.0094 (6) |
C10 | 0.0682 (11) | 0.0370 (8) | 0.0346 (8) | −0.0246 (8) | −0.0123 (7) | −0.0075 (6) |
C11 | 0.0269 (7) | 0.0278 (6) | 0.0334 (7) | −0.0116 (5) | −0.0005 (5) | −0.0090 (5) |
C12 | 0.0256 (7) | 0.0362 (7) | 0.0364 (7) | −0.0160 (6) | 0.0027 (5) | −0.0140 (6) |
C13 | 0.0345 (8) | 0.0370 (8) | 0.0478 (8) | −0.0144 (6) | −0.0003 (6) | −0.0178 (6) |
C14 | 0.0366 (8) | 0.0517 (9) | 0.0687 (11) | −0.0154 (7) | 0.0028 (8) | −0.0377 (9) |
C15 | 0.0387 (9) | 0.0788 (12) | 0.0558 (10) | −0.0300 (9) | 0.0116 (7) | −0.0461 (9) |
C16 | 0.0409 (9) | 0.0744 (12) | 0.0370 (8) | −0.0315 (8) | 0.0033 (6) | −0.0216 (8) |
C17 | 0.0289 (7) | 0.0464 (8) | 0.0377 (8) | −0.0158 (6) | 0.0018 (6) | −0.0136 (6) |
C18 | 0.0257 (7) | 0.0291 (6) | 0.0294 (7) | −0.0103 (5) | −0.0008 (5) | −0.0074 (5) |
C19 | 0.0220 (6) | 0.0314 (7) | 0.0315 (7) | −0.0108 (5) | 0.0004 (5) | −0.0096 (5) |
C20 | 0.0345 (7) | 0.0357 (7) | 0.0315 (7) | −0.0161 (6) | −0.0003 (5) | −0.0086 (6) |
C21 | 0.0445 (9) | 0.0480 (9) | 0.0342 (7) | −0.0222 (7) | 0.0007 (6) | −0.0169 (6) |
C22 | 0.0430 (9) | 0.0382 (8) | 0.0495 (9) | −0.0191 (7) | 0.0036 (7) | −0.0222 (7) |
C23 | 0.0472 (9) | 0.0303 (7) | 0.0461 (9) | −0.0146 (6) | −0.0064 (7) | −0.0075 (6) |
C24 | 0.0361 (8) | 0.0343 (7) | 0.0346 (7) | −0.0137 (6) | −0.0059 (6) | −0.0084 (6) |
C25 | 0.0308 (10) | 0.0853 (15) | 0.1151 (19) | −0.0114 (9) | −0.0110 (10) | −0.0478 (14) |
C26 | 0.0476 (10) | 0.0519 (10) | 0.0647 (11) | −0.0186 (8) | 0.0220 (9) | −0.0228 (9) |
C27 | 0.0444 (9) | 0.0433 (8) | 0.0531 (9) | −0.0272 (7) | 0.0110 (7) | −0.0207 (7) |
F1—C15 | 1.3637 (18) | C12—C17 | 1.386 (2) |
F2—C22 | 1.3640 (17) | C13—H13 | 0.9500 |
O1—C2 | 1.359 (2) | C13—C14 | 1.383 (2) |
O1—C25 | 1.428 (2) | C14—H14 | 0.9500 |
O2—C7 | 1.368 (2) | C14—C15 | 1.370 (3) |
O2—C26 | 1.414 (2) | C15—C16 | 1.372 (3) |
O3—C11 | 1.4425 (16) | C16—H16 | 0.9500 |
O3—C27 | 1.4273 (18) | C16—C17 | 1.387 (2) |
O4—C18 | 1.4166 (16) | C17—H17 | 0.9500 |
O4—H4 | 0.84 (2) | C18—C19 | 1.5269 (18) |
C1—C2 | 1.378 (2) | C19—C20 | 1.3917 (19) |
C1—C9 | 1.411 (2) | C19—C24 | 1.3872 (19) |
C1—C11 | 1.5239 (19) | C20—H20 | 0.9500 |
C2—C3 | 1.427 (3) | C20—C21 | 1.389 (2) |
C3—H3 | 0.9500 | C21—H21 | 0.9500 |
C3—C4 | 1.364 (3) | C21—C22 | 1.372 (2) |
C4—H4A | 0.9500 | C22—C23 | 1.367 (2) |
C4—C10 | 1.407 (3) | C23—H23 | 0.9500 |
C5—H5 | 0.9500 | C23—C24 | 1.392 (2) |
C5—C6 | 1.362 (3) | C24—H24 | 0.9500 |
C5—C10 | 1.419 (3) | C25—H25A | 0.9800 |
C6—H6 | 0.9500 | C25—H25B | 0.9800 |
C6—C7 | 1.417 (2) | C25—H25C | 0.9800 |
C7—C8 | 1.375 (2) | C26—H26A | 0.9800 |
C8—C9 | 1.401 (2) | C26—H26B | 0.9800 |
C8—C18 | 1.5133 (18) | C26—H26C | 0.9800 |
C9—C10 | 1.408 (2) | C27—H27A | 0.9800 |
C11—C12 | 1.5141 (19) | C27—H27B | 0.9800 |
C11—C18 | 1.6248 (18) | C27—H27C | 0.9800 |
C12—C13 | 1.393 (2) | ||
C2—O1—C25 | 119.03 (16) | F1—C15—C16 | 118.41 (17) |
C7—O2—C26 | 118.84 (14) | C14—C15—C16 | 122.98 (15) |
C27—O3—C11 | 116.01 (11) | C15—C16—H16 | 121.1 |
C18—O4—H4 | 106.2 (16) | C15—C16—C17 | 117.80 (16) |
C2—C1—C9 | 118.08 (14) | C17—C16—H16 | 121.1 |
C2—C1—C11 | 133.46 (14) | C12—C17—C16 | 121.32 (15) |
C9—C1—C11 | 108.01 (12) | C12—C17—H17 | 119.3 |
O1—C2—C1 | 117.94 (15) | C16—C17—H17 | 119.3 |
O1—C2—C3 | 123.50 (15) | O4—C18—C8 | 114.24 (11) |
C1—C2—C3 | 118.53 (16) | O4—C18—C11 | 110.16 (10) |
C2—C3—H3 | 118.8 | O4—C18—C19 | 106.73 (11) |
C4—C3—C2 | 122.39 (16) | C8—C18—C11 | 101.96 (10) |
C4—C3—H3 | 118.8 | C8—C18—C19 | 112.03 (11) |
C3—C4—H4A | 119.6 | C19—C18—C11 | 111.78 (10) |
C3—C4—C10 | 120.78 (15) | C20—C19—C18 | 119.58 (12) |
C10—C4—H4A | 119.6 | C24—C19—C18 | 121.77 (12) |
C6—C5—H5 | 119.3 | C24—C19—C20 | 118.63 (13) |
C6—C5—C10 | 121.46 (15) | C19—C20—H20 | 119.5 |
C10—C5—H5 | 119.3 | C21—C20—C19 | 120.95 (13) |
C5—C6—H6 | 119.3 | C21—C20—H20 | 119.5 |
C5—C6—C7 | 121.39 (16) | C20—C21—H21 | 120.8 |
C7—C6—H6 | 119.3 | C22—C21—C20 | 118.35 (14) |
O2—C7—C6 | 123.20 (14) | C22—C21—H21 | 120.8 |
O2—C7—C8 | 117.86 (14) | F2—C22—C21 | 118.38 (14) |
C8—C7—C6 | 118.89 (16) | F2—C22—C23 | 118.95 (14) |
C7—C8—C9 | 119.25 (13) | C23—C22—C21 | 122.66 (14) |
C7—C8—C18 | 131.42 (14) | C22—C23—H23 | 120.8 |
C9—C8—C18 | 109.19 (12) | C22—C23—C24 | 118.42 (14) |
C8—C9—C1 | 112.86 (12) | C24—C23—H23 | 120.8 |
C8—C9—C10 | 123.07 (15) | C19—C24—C23 | 120.98 (14) |
C10—C9—C1 | 124.07 (15) | C19—C24—H24 | 119.5 |
C4—C10—C5 | 128.23 (15) | C23—C24—H24 | 119.5 |
C4—C10—C9 | 116.01 (16) | O1—C25—H25A | 109.5 |
C9—C10—C5 | 115.74 (16) | O1—C25—H25B | 109.5 |
O3—C11—C1 | 109.27 (11) | O1—C25—H25C | 109.5 |
O3—C11—C12 | 110.59 (11) | H25A—C25—H25B | 109.5 |
O3—C11—C18 | 101.39 (10) | H25A—C25—H25C | 109.5 |
C1—C11—C18 | 102.50 (10) | H25B—C25—H25C | 109.5 |
C12—C11—C1 | 118.16 (11) | O2—C26—H26A | 109.5 |
C12—C11—C18 | 113.41 (11) | O2—C26—H26B | 109.5 |
C13—C12—C11 | 121.58 (13) | O2—C26—H26C | 109.5 |
C17—C12—C11 | 119.66 (12) | H26A—C26—H26B | 109.5 |
C17—C12—C13 | 118.69 (14) | H26A—C26—H26C | 109.5 |
C12—C13—H13 | 119.6 | H26B—C26—H26C | 109.5 |
C14—C13—C12 | 120.74 (15) | O3—C27—H27A | 109.5 |
C14—C13—H13 | 119.6 | O3—C27—H27B | 109.5 |
C13—C14—H14 | 120.8 | O3—C27—H27C | 109.5 |
C15—C14—C13 | 118.43 (16) | H27A—C27—H27B | 109.5 |
C15—C14—H14 | 120.8 | H27A—C27—H27C | 109.5 |
F1—C15—C14 | 118.61 (17) | H27B—C27—H27C | 109.5 |
F1—C15—C16—C17 | −176.86 (14) | C9—C1—C11—O3 | 87.60 (13) |
F2—C22—C23—C24 | 179.41 (14) | C9—C1—C11—C12 | −144.84 (12) |
O1—C2—C3—C4 | 174.48 (16) | C9—C1—C11—C18 | −19.37 (14) |
O2—C7—C8—C9 | −177.25 (13) | C9—C8—C18—O4 | −137.95 (12) |
O2—C7—C8—C18 | −1.9 (2) | C9—C8—C18—C11 | −19.14 (13) |
O3—C11—C12—C13 | 148.52 (13) | C9—C8—C18—C19 | 100.53 (13) |
O3—C11—C12—C17 | −34.66 (17) | C10—C5—C6—C7 | 2.6 (3) |
O3—C11—C18—O4 | 31.44 (13) | C11—C1—C2—O1 | −5.4 (3) |
O3—C11—C18—C8 | −90.22 (11) | C11—C1—C2—C3 | 172.69 (15) |
O3—C11—C18—C19 | 149.93 (10) | C11—C1—C9—C8 | 8.32 (16) |
O4—C18—C19—C20 | 34.99 (16) | C11—C1—C9—C10 | −171.21 (13) |
O4—C18—C19—C24 | −146.74 (13) | C11—C12—C13—C14 | 178.65 (13) |
C1—C2—C3—C4 | −3.5 (3) | C11—C12—C17—C16 | −177.26 (13) |
C1—C9—C10—C4 | −3.6 (2) | C11—C18—C19—C20 | −85.53 (14) |
C1—C9—C10—C5 | 175.15 (14) | C11—C18—C19—C24 | 92.74 (15) |
C1—C11—C12—C13 | 21.59 (19) | C12—C11—C18—O4 | −87.12 (13) |
C1—C11—C12—C17 | −161.59 (13) | C12—C11—C18—C8 | 151.21 (11) |
C1—C11—C18—O4 | 144.36 (11) | C12—C11—C18—C19 | 31.37 (15) |
C1—C11—C18—C8 | 22.70 (12) | C12—C13—C14—C15 | −1.3 (2) |
C1—C11—C18—C19 | −97.14 (12) | C13—C12—C17—C16 | −0.3 (2) |
C2—C1—C9—C8 | −178.37 (13) | C13—C14—C15—F1 | 178.26 (14) |
C2—C1—C9—C10 | 2.1 (2) | C13—C14—C15—C16 | −0.8 (3) |
C2—C1—C11—O3 | −84.26 (19) | C14—C15—C16—C17 | 2.2 (3) |
C2—C1—C11—C12 | 43.3 (2) | C15—C16—C17—C12 | −1.6 (2) |
C2—C1—C11—C18 | 168.77 (16) | C17—C12—C13—C14 | 1.8 (2) |
C2—C3—C4—C10 | 1.9 (3) | C18—C8—C9—C1 | 7.86 (16) |
C3—C4—C10—C5 | −177.04 (17) | C18—C8—C9—C10 | −172.60 (13) |
C3—C4—C10—C9 | 1.6 (2) | C18—C11—C12—C13 | −98.36 (15) |
C5—C6—C7—O2 | 174.01 (15) | C18—C11—C12—C17 | 78.45 (15) |
C5—C6—C7—C8 | −3.3 (2) | C18—C19—C20—C21 | 177.64 (13) |
C6—C5—C10—C4 | 179.75 (16) | C18—C19—C24—C23 | −177.47 (13) |
C6—C5—C10—C9 | 1.2 (2) | C19—C20—C21—C22 | −0.2 (2) |
C6—C7—C8—C9 | 0.3 (2) | C20—C19—C24—C23 | 0.8 (2) |
C6—C7—C8—C18 | 175.57 (14) | C20—C21—C22—F2 | −179.28 (13) |
C7—C8—C9—C1 | −175.85 (13) | C20—C21—C22—C23 | 1.0 (2) |
C7—C8—C9—C10 | 3.7 (2) | C21—C22—C23—C24 | −0.8 (3) |
C7—C8—C18—O4 | 46.4 (2) | C22—C23—C24—C19 | −0.1 (2) |
C7—C8—C18—C11 | 165.18 (15) | C24—C19—C20—C21 | −0.7 (2) |
C7—C8—C18—C19 | −75.15 (19) | C25—O1—C2—C1 | −170.50 (16) |
C8—C9—C10—C4 | 176.89 (14) | C25—O1—C2—C3 | 11.5 (3) |
C8—C9—C10—C5 | −4.3 (2) | C26—O2—C7—C6 | 17.1 (2) |
C8—C18—C19—C20 | 160.74 (12) | C26—O2—C7—C8 | −165.49 (14) |
C8—C18—C19—C24 | −20.99 (18) | C27—O3—C11—C1 | 66.72 (15) |
C9—C1—C2—O1 | −176.62 (13) | C27—O3—C11—C12 | −64.99 (15) |
C9—C1—C2—C3 | 1.5 (2) | C27—O3—C11—C18 | 174.44 (11) |
Cg2, Cg5, Cg8 and Cg9 are the centroids of the rings (C1–C4,C9,C10), (C19–C24), (C1–C10) and (C1–C8,C10,C11,C18), respectively. |
D—H···A | D—H | H···A | D···A | D—H···A |
O4—H4···O3 | 0.83 (3) | 2.00 (3) | 2.5119 (18) | 119 (3) |
C24—H24···Cg9 | 0.95 | 2.90 | 3.4960 (17) | 122 |
C20—H20···O4i | 0.95 | 2.49 | 3.3554 (17) | 151 |
C4—H4A···F1ii | 0.95 | 2.44 | 3.189 (3) | 135 |
C26—H26C···Cg2iii | 0.95 | 2.70 | 3.614 (2) | 155 |
C26—H26C···Cg8iii | 0.95 | 2.85 | 3.747 (2) | 153 |
C26—H26C···Cg9iii | 0.95 | 2.91 | 3.848 (2) | 160 |
C25—H25B···Cg5iv | 0.95 | 2.81 | 3.527 (3) | 131 |
Symmetry codes: (i) −x, −y+1, −z+1; (ii) x, y, z+1; (iii) −x, −y+1, −z+2; (iv) x+1, y, z. |
Acknowledgements
The authors express their gratitude to Professor Keiichi Noguchi, Instrumentation Analysis Center, Tokyo University of Agriculture and Technology, for technical advice.
Funding information
This work was supported by JSPS KAKENHI Grant No. JP20K05473.
References
Biedermann, P. U., Stezowski, J. J. & Agranat, I. (2001). Eur. J. Org. Chem. pp. 15–34. CrossRef Google Scholar
Burla, M. C., Caliandro, R., Camalli, M., Carrozzini, B., Cascarano, G. L., De Caro, L., Giacovazzo, C., Polidori, G., Siliqi, D. & Spagna, R. (2007). J. Appl. Cryst. 40, 609–613. Web of Science CrossRef CAS IUCr Journals Google Scholar
Cremer, D. & Pople, J. A. (1975). J. Am. Chem. Soc. 97, 1354–1358. CrossRef CAS Web of Science Google Scholar
Dolomanov, O. V., Bourhis, L. J., Gildea, R. J., Howard, J. A. K. & Puschmann, H. (2009). J. Appl. Cryst. 42, 339–341. Web of Science CrossRef CAS IUCr Journals Google Scholar
Downing, G. A., Frampton, C. S., MacNicol, D. D. & Mallinson, P. R. (1994). Angew. Chem. Int. Ed. Engl. 33, 1587–1589. CSD CrossRef Web of Science Google Scholar
Gatilov, Y. V., Nagi, S. M., Rybalova, T. V. & Borodkin, G. I. (1984). Zh. Strukt. Khim. (Russ. J. Struct. Chem.), 25, 142. Google Scholar
Groom, C. R., Bruno, I. J., Lightfoot, M. P. & Ward, S. C. (2016). Acta Cryst. B72, 171–179. Web of Science CrossRef IUCr Journals Google Scholar
Guo, W.-S., Guo, F., Deng, F., Tong, J., Liu, Q.-T., Zhang, Y.-L., Wu, T.-Q., Cai, Y.-P., Ma, M.-Y., Cao, S.-L., Cheng, G.-R., Zheng, Q.-T. & Lu, Y. (2000). Huaxue Xuebao (Chin.) (Acta Chim. Sinica), 58, 996. Google Scholar
Hayward, L. D. & Csizmadia, I. G. (1963). Tetrahedron, 19, 2111–2121. CrossRef CAS Google Scholar
Higashi, T. (1999). NUMABS. Rigaku Corporation, Tokyo, Japan. Google Scholar
Jimenez, R. P., Parvez, M. & Sutherland, T. C. (2007). Acta Cryst. E63, o504–o505. CSD CrossRef IUCr Journals Google Scholar
Joussot, J., Schoenfelder, A., Suffert, J. & Blond, G. (2016). Private Communication (refcodes UYENET, UYENIX and UYENIX01). CCDC, Cambridge, England. Google Scholar
Joussot, J., Schoenfelder, A., Suffert, J. & Blond, G. (2017). Comperes Rendius Chimie, 20, 665-681. CSD CrossRef CAS Google Scholar
Luger, P. & Bülow, R. (1983). J. Appl. Cryst. 16, 431–432. CrossRef CAS Web of Science IUCr Journals Google Scholar
Maghsoodlou, M. T., Hazeri, N., Habibi-Khorassani, S. M., Ziyaadini, M., Marandi, G., Khandan-Barani, K., Ebrahimi, P., Charati, F. R., Sobolev, A. & Makha, M. (2009). J. Heterocycl. Chem. 46, 843–848. CSD CrossRef CAS Google Scholar
Mak, T. C. W. & Trotter, J. (1963). Acta Cryst. 16, 324. CSD CrossRef IUCr Journals Google Scholar
Mak, T. C. W. & Trotter, J. (1964). Acta Cryst. 17, 367–373. CSD CrossRef IUCr Journals Google Scholar
Mido, T., Iitsuka, H., Kobayashi, M., Noguchi, K., Yonezawa, N. & Okamoto, A. (2020). Chem. Lett. 49, 295–298. CrossRef CAS Google Scholar
Mido, T., Iitsuka, H., Yokoyama, T., Takahara, G., Ogata, K., Yonezawa, N. & Okamoto, A. (2017). Eur. Chem. Bull. 6, 273–280. CrossRef CAS Google Scholar
Moriconi, E. J., O'Connor, W. F., Kuhn, L. P., Keneally, E. A. & Wallenberger, F. T. (1959). J. Am. Chem. Soc. 81, 6472–6477. CrossRef CAS Google Scholar
Myhill, J. A., Wilhelmsen, C. A., Zhang, L. & Morken, J. P. (2018). J. Am. Chem. Soc. 140, 15181–15185. CSD CrossRef CAS PubMed Google Scholar
Nair, V., Sheela, K. C., Rath, N. P. & Eigendorf, G. K. (2000). Tetrahedron Lett. 41, 6217–6221. CSD CrossRef CAS Google Scholar
Okamoto, A., Mitsui, R., Oike, H. & Yonezawa, N. (2011). Chem. Lett. 40, 1283–1284. Web of Science CrossRef CAS Google Scholar
Okamoto, A. & Yonezawa, N. (2009). Chem. Lett. 38, 914–915. Web of Science CrossRef CAS Google Scholar
Okamoto, A. & Yonezawa, N. (2015). J. Syn. Org. Chem. Jpn. 73, 339–360. Web of Science CrossRef CAS Google Scholar
Parvez, M., Simion, D. V. & Sorensen, T. S. (2001). Acta Cryst. E57, o366–o367. CSD CrossRef IUCr Journals Google Scholar
Pascal, R. A. (2006). Chem. Rev. 106, 4809–4819. Web of Science CrossRef PubMed CAS Google Scholar
Plater, M. J., Schmidt, D. M. & Howie, R. A. (1997). J. Chem. Res. 116, 720. Google Scholar
Rigaku (1998). PROCESS-AUTO. Rigaku Corporation, Tokyo, Japan. Google Scholar
Rigaku (2010). CrystalStructure. Rigaku Corporation, Tokyo, Japan. Google Scholar
Sato, H., Fukaya, K., Poudel, B. S. & Krische, M. J. (2017). Angew. Chem. Int. Ed. 56, 14667–14671. CSD CrossRef CAS Google Scholar
Sheldrick, G. M. (2015). Acta Cryst. C71, 3–8. Web of Science CrossRef IUCr Journals Google Scholar
Suzuki, T., Ichioka, K., Higuchi, H., Kawai, H., Fujiwara, K., Ohkita, M., Tsuji, T. & Takahashi, Y. (2005). J. Org. Chem. 70, 5592–5598. CSD CrossRef PubMed CAS Google Scholar
Takada, T., Hijikata, D., Okamoto, A., Oike, H. & Yonezawa, N. (2011). Acta Cryst. E67, o2562–o2563. CSD CrossRef IUCr Journals Google Scholar
Tannaci, J. F., Noji, M., McBee, J. & Tilley, T. D. (2007). J. Org. Chem. 72, 5567–5573. Web of Science CSD CrossRef PubMed CAS Google Scholar
Tao, X., Daniliuc, C. G., Knitsch, R., Hansen, M. R., Eckert, H., Lübbesmeyer, M., Studer, A., Kehr, G. & Erker, G. (2018). Chem. Sci. 9, 8011–8018. CSD CrossRef CAS PubMed Google Scholar
Trotter, J. & Mak, T. C. W. (1963). Acta Cryst. 16, 1032–1037. CSD CrossRef CAS IUCr Journals Web of Science Google Scholar
This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.