Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536807049902/zl2071sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S1600536807049902/zl2071Isup2.hkl |
CCDC reference: 667370
Key indicators
- Single-crystal X-ray study
- T = 100 K
- Mean (C-C) = 0.002 Å
- R factor = 0.045
- wR factor = 0.119
- Data-to-parameter ratio = 13.3
checkCIF/PLATON results
No syntax errors found
Alert level C PLAT029_ALERT_3_C _diffrn_measured_fraction_theta_full Low ....... 0.98 PLAT094_ALERT_2_C Ratio of Maximum / Minimum Residual Density .... 2.50
0 ALERT level A = In general: serious problem 0 ALERT level B = Potentially serious problem 2 ALERT level C = Check and explain 0 ALERT level G = General alerts; check 0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data 1 ALERT type 2 Indicator that the structure model may be wrong or deficient 1 ALERT type 3 Indicator that the structure quality may be low 0 ALERT type 4 Improvement, methodology, query or suggestion 0 ALERT type 5 Informative message, check
To a microwave vial were added Pd(PPh3)4 (23.1 mg, 0.02 mmol), benzene boronic acid (97.5 mg, 0.8 mmol), 3-fluoro-4-iodo-2,5-diphenyl -furan (74.4 mg, 0.2 mmol) in 4.0 ml of toluene, 0.4 ml EtOH, and 0.4 ml of aq. 2M Na2CO3. The vial was capped and purged with argon before microwave irradiation (388 K, 30 min). Column chromatography (neat hexane/silica) yielded the title compound (63.0 mg, 98%). Crystals for X-ray analysis were obtained upon slow evaporation of a hexane solution of the title compound at room temperature.
Phenyl hydrogen atoms were located from difference maps and refined isotropically. C—H Bond distances range from 0.958 (17) Å to 1.01 (2) Å with an average of 0.977 (19) Å. The highest peak, 0.59 e/Å3, and deepest trough, -0.24 e/Å3, are located 1.53 Å from O1 and 0.46 Å from F1, respectively.
The furan ring system is a critical structural moiety of a variety of natural products, active pharmaceuticals, agricultural compounds, and synthetic precursors. One particularly underdeveloped area of furan chemistry is the synthesis of fluorine containing systems. This is exceptionally puzzling due to the interesting pharmokinetic properties fluorine can instill into the parent molecule (Uneyama, 2006; Schlosser, 1998; Hammond, 2005). Recently, our group reported the facile, indium mediated synthesis of α,α-difluorohomopropargyl alcohols (Arimitsu & Hammond, 2006; Arimitsu et al., 2007). The synthetic usefulness of these alcohols in heterocyclizations was demonstrated with a silver catalyzed synthesis of 3-fluoro-2,5-disubstituted furans. If an electrophile could be trapped using this methodology it could provide a critical synthetic handle at the 4-position of the fluorofurans, which in turn could provide ready access to hitherto unknown 3-fluoro-2,4,5-trisubstituted furans such as the title compound.
A search of the Cambridge crystallographic database revealed that the title compound represents the first structurally characterized fully substituted fluorofuran (Allen, 2002). The atomic labelling scheme is shown in Fig. 1 (ORTEP-3, Farrugia, 1997) and a partial packing diagram (Fig. 2) identifies the aromatic rings involved in the intermolecular π stacking analysis (Janiak, 2000). Neighboring five-membered furan rings are involved in two intermolecular π-π stacking interactions along the crystallographic a axis. The first slipped stack interaction between furan rings is 3.61 (4) Å, between C2 at (x, y, z) and the centroid of the five-memebered ring at (x + 0.5. y, 0.5 - z). There is a second slipped π stack interaction of 3.64 (4) Å from C1 at (x + 0.5. y, 0.5 - z) to the centroid of the furan ring at (x, y, z). There are also two slipped π stack intermolecular interactions formed between the phenyl group containing C5—C10 (Ph1) at (x, y, z) with the phenyl group containing C17—C22 (Ph3) of the neighboring molecule at (x + 0.5. y, 0.5 - z). The intermolecular C7 (x, y, z) to C17—C22 centroid distance is 3.53 (4) Å. The second intermolecular interaction of 3.64 (4) Å is between C17 (x + 0.5. y, 0.5 - z) and the C5—C10 centroid.
The fluorine atom sits (dev 0.007 (1) Å) in the same plane as the furan ring, which has a mean deviation of 0.009 (1) Å. The F1—H6 non-bonded contact is 2.416 (17) Å with a F1···C6 separation of 3.0814 (17) Å and the C6—H6···F1 angle is 126.3 (4)°. The O1···H10 non-bonded contact is 2.491 (17) Å with a O1···C10 separation of 2.8250 (16) Å and the C10—H10···O1 angle is 99.0 (4)°. Neither is representative of a classical intramolecular hydrogen bond (Desiraju, 1995). It is however noteworthy that the C5—C10 phenyl plane (dev 0.001 (1) Å), located between F1 and O1, is only 9.55 (7)° from being coplanar with the furan ring, whereas the C11—C16 (dev 0.008 (1) Å) and the C17—C22 (dev 0.004 (1) Å) aromatic planes form angles of 41.71° and 20.45°, respectively, with the five-membered furan ring. The X-ray structure of the related complex 3-fluoro-2-(4-methoxyphenyl)-5-phenylfuran previously reported (Xu & Chen, 2003; CSD refcode HACYUG) contains two aromatic substiuents and shows similar π stacking interactions to the title compound. Interestingly, the methoxyphenyl group located at position 2 of the furan ring in this compound is also nearly coplanar (angle of 1.99°) with the furan plane. The fact that the only two crystal structures known for fluorofurans both show this coplanarity may suggest the possibility of an F···H interaction, but this needs to be proven with more structurally related analogues.
For related literature, see: Hammond (2005); Schlosser (1998); Uneyama (2006); Allen (2002); Arimitsu & Hammond (2006); Arimitsu et al. (2007); Desiraju (1995); Janiak (2000); Xu & Chen (2003).
Data collection: SMART (Bruker, 2002); cell refinement: SAINT (Bruker, 2002); data reduction: SAINT (Bruker, 2002); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 2001) and ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: SHELXTL (Bruker, 2001).
C22H15FO | F(000) = 1312 |
Mr = 314.34 | Dx = 1.348 Mg m−3 |
Orthorhombic, Pbca | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ac 2ab | Cell parameters from 8241 reflections |
a = 7.5865 (9) Å | θ = 2.3–28.1° |
b = 19.9375 (15) Å | µ = 0.09 mm−1 |
c = 20.4751 (19) Å | T = 100 K |
V = 3097.0 (5) Å3 | Prism, colorless |
Z = 8 | 0.41 × 0.38 × 0.35 mm |
Bruker SMART APEX diffractometer | 3687 independent reflections |
Radiation source: fine-focus sealed tube | 3398 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.021 |
ω scans | θmax = 28.1°, θmin = 2.0° |
Absorption correction: multi-scan (SADABS; Sheldrick, 2001) | h = −10→9 |
Tmin = 0.861, Tmax = 0.962 | k = −26→26 |
24875 measured reflections | l = −26→26 |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.045 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.119 | All H-atom parameters refined |
S = 1.06 | w = 1/[σ2(Fo2) + (0.0604P)2 + 1.6834P] where P = (Fo2 + 2Fc2)/3 |
3687 reflections | (Δ/σ)max < 0.001 |
277 parameters | Δρmax = 0.59 e Å−3 |
0 restraints | Δρmin = −0.24 e Å−3 |
C22H15FO | V = 3097.0 (5) Å3 |
Mr = 314.34 | Z = 8 |
Orthorhombic, Pbca | Mo Kα radiation |
a = 7.5865 (9) Å | µ = 0.09 mm−1 |
b = 19.9375 (15) Å | T = 100 K |
c = 20.4751 (19) Å | 0.41 × 0.38 × 0.35 mm |
Bruker SMART APEX diffractometer | 3687 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick, 2001) | 3398 reflections with I > 2σ(I) |
Tmin = 0.861, Tmax = 0.962 | Rint = 0.021 |
24875 measured reflections |
R[F2 > 2σ(F2)] = 0.045 | 0 restraints |
wR(F2) = 0.119 | All H-atom parameters refined |
S = 1.06 | Δρmax = 0.59 e Å−3 |
3687 reflections | Δρmin = −0.24 e Å−3 |
277 parameters |
Experimental. Data were collected with a Bruker SMART APEX CCD-based diffractometer using /w-scans of width 0.3 °. and 30 s duration at a crystal-to-detector distance of 4.908 cm. Intensity decay over the course of the data collection was evaluated by recollecting the first 50 frames of data at the end of the experiment. No significant decay was noted. |
x | y | z | Uiso*/Ueq | ||
O1 | 0.24250 (12) | 0.14903 (4) | 0.30129 (4) | 0.0193 (2) | |
F1 | 0.36667 (12) | 0.26745 (4) | 0.18364 (4) | 0.0268 (2) | |
C1 | 0.26352 (17) | 0.16753 (6) | 0.23730 (6) | 0.0188 (3) | |
C2 | 0.32872 (17) | 0.23095 (6) | 0.23764 (6) | 0.0195 (3) | |
C3 | 0.34605 (16) | 0.25496 (6) | 0.30272 (6) | 0.0194 (3) | |
C4 | 0.29465 (15) | 0.20144 (6) | 0.34049 (6) | 0.0184 (3) | |
C5 | 0.20939 (16) | 0.12118 (6) | 0.18630 (6) | 0.0195 (3) | |
C6 | 0.2446 (2) | 0.13500 (7) | 0.12062 (7) | 0.0260 (3) | |
H6 | 0.308 (2) | 0.1752 (9) | 0.1103 (8) | 0.027 (4)* | |
C7 | 0.1890 (2) | 0.09044 (8) | 0.07241 (7) | 0.0304 (3) | |
H7 | 0.215 (2) | 0.1031 (9) | 0.0283 (10) | 0.037 (5)* | |
C8 | 0.0992 (2) | 0.03254 (8) | 0.08894 (7) | 0.0303 (3) | |
H8 | 0.060 (3) | 0.0013 (10) | 0.0532 (9) | 0.045 (5)* | |
C9 | 0.0633 (2) | 0.01869 (7) | 0.15384 (7) | 0.0292 (3) | |
H9 | −0.003 (3) | −0.0234 (10) | 0.1652 (9) | 0.038 (5)* | |
C10 | 0.11767 (18) | 0.06254 (7) | 0.20227 (7) | 0.0243 (3) | |
H10 | 0.091 (2) | 0.0522 (8) | 0.2489 (9) | 0.030 (4)* | |
C11 | 0.39500 (16) | 0.32426 (6) | 0.32030 (6) | 0.0191 (3) | |
C12 | 0.30502 (17) | 0.36018 (6) | 0.36857 (6) | 0.0209 (3) | |
H12 | 0.210 (2) | 0.3385 (8) | 0.3916 (8) | 0.025 (4)* | |
C13 | 0.35095 (18) | 0.42630 (7) | 0.38218 (6) | 0.0237 (3) | |
H13 | 0.288 (2) | 0.4511 (9) | 0.4165 (9) | 0.033 (5)* | |
C14 | 0.48662 (19) | 0.45735 (7) | 0.34824 (7) | 0.0256 (3) | |
H14 | 0.519 (2) | 0.5038 (9) | 0.3574 (8) | 0.029 (4)* | |
C15 | 0.57389 (19) | 0.42260 (7) | 0.29931 (7) | 0.0256 (3) | |
H15 | 0.666 (2) | 0.4434 (9) | 0.2744 (9) | 0.033 (5)* | |
C16 | 0.52771 (18) | 0.35688 (7) | 0.28521 (6) | 0.0227 (3) | |
H16 | 0.588 (2) | 0.3326 (8) | 0.2512 (8) | 0.023 (4)* | |
C17 | 0.29370 (16) | 0.18711 (6) | 0.41057 (6) | 0.0186 (3) | |
C18 | 0.19434 (18) | 0.13319 (7) | 0.43419 (7) | 0.0233 (3) | |
H18 | 0.118 (2) | 0.1069 (8) | 0.4032 (9) | 0.029 (4)* | |
C19 | 0.1970 (2) | 0.11738 (7) | 0.50027 (7) | 0.0277 (3) | |
H19 | 0.126 (2) | 0.0805 (9) | 0.5154 (9) | 0.034 (5)* | |
C20 | 0.2979 (2) | 0.15475 (7) | 0.54358 (7) | 0.0276 (3) | |
H20 | 0.297 (2) | 0.1453 (9) | 0.5882 (9) | 0.030 (4)* | |
C21 | 0.39791 (19) | 0.20809 (7) | 0.52025 (6) | 0.0248 (3) | |
H21 | 0.470 (2) | 0.2344 (8) | 0.5490 (8) | 0.026 (4)* | |
C22 | 0.39726 (17) | 0.22406 (6) | 0.45427 (6) | 0.0210 (3) | |
H22 | 0.474 (2) | 0.2595 (8) | 0.4383 (8) | 0.024 (4)* |
U11 | U22 | U33 | U12 | U13 | U23 | |
O1 | 0.0223 (4) | 0.0194 (4) | 0.0161 (4) | 0.0000 (3) | −0.0005 (3) | −0.0001 (3) |
F1 | 0.0369 (5) | 0.0251 (4) | 0.0184 (4) | −0.0011 (3) | 0.0038 (3) | 0.0047 (3) |
C1 | 0.0195 (6) | 0.0210 (6) | 0.0160 (6) | 0.0033 (5) | 0.0010 (4) | 0.0013 (4) |
C2 | 0.0220 (6) | 0.0194 (6) | 0.0170 (6) | 0.0029 (5) | 0.0006 (5) | 0.0018 (4) |
C3 | 0.0183 (5) | 0.0209 (6) | 0.0191 (6) | 0.0030 (5) | −0.0001 (4) | 0.0004 (4) |
C4 | 0.0178 (6) | 0.0181 (6) | 0.0194 (6) | 0.0014 (4) | −0.0015 (4) | −0.0027 (4) |
C5 | 0.0194 (6) | 0.0214 (6) | 0.0177 (6) | 0.0050 (5) | −0.0012 (4) | −0.0011 (4) |
C6 | 0.0307 (7) | 0.0277 (7) | 0.0195 (6) | 0.0050 (6) | 0.0016 (5) | 0.0019 (5) |
C7 | 0.0369 (8) | 0.0371 (8) | 0.0173 (6) | 0.0111 (6) | −0.0014 (6) | −0.0011 (5) |
C8 | 0.0319 (7) | 0.0317 (7) | 0.0273 (7) | 0.0068 (6) | −0.0091 (6) | −0.0077 (6) |
C9 | 0.0293 (7) | 0.0271 (7) | 0.0311 (7) | −0.0010 (6) | −0.0049 (6) | −0.0040 (6) |
C10 | 0.0248 (6) | 0.0245 (6) | 0.0235 (6) | 0.0007 (5) | −0.0011 (5) | −0.0013 (5) |
C11 | 0.0204 (6) | 0.0182 (6) | 0.0186 (6) | 0.0024 (5) | −0.0032 (4) | 0.0022 (4) |
C12 | 0.0223 (6) | 0.0221 (6) | 0.0182 (6) | 0.0015 (5) | −0.0006 (5) | 0.0019 (5) |
C13 | 0.0292 (7) | 0.0226 (6) | 0.0193 (6) | 0.0052 (5) | −0.0042 (5) | −0.0009 (5) |
C14 | 0.0326 (7) | 0.0186 (6) | 0.0255 (6) | −0.0001 (5) | −0.0081 (5) | 0.0025 (5) |
C15 | 0.0259 (6) | 0.0236 (6) | 0.0273 (7) | −0.0022 (5) | −0.0017 (5) | 0.0060 (5) |
C16 | 0.0229 (6) | 0.0230 (6) | 0.0221 (6) | 0.0028 (5) | 0.0008 (5) | 0.0023 (5) |
C17 | 0.0182 (6) | 0.0183 (6) | 0.0195 (6) | 0.0030 (4) | 0.0005 (4) | 0.0009 (4) |
C18 | 0.0242 (6) | 0.0220 (6) | 0.0236 (6) | −0.0014 (5) | 0.0010 (5) | 0.0009 (5) |
C19 | 0.0318 (7) | 0.0256 (7) | 0.0258 (7) | −0.0016 (6) | 0.0062 (6) | 0.0050 (5) |
C20 | 0.0374 (8) | 0.0273 (7) | 0.0180 (6) | 0.0075 (6) | 0.0037 (5) | 0.0021 (5) |
C21 | 0.0305 (7) | 0.0232 (6) | 0.0207 (6) | 0.0051 (5) | −0.0032 (5) | −0.0031 (5) |
C22 | 0.0225 (6) | 0.0190 (6) | 0.0215 (6) | 0.0009 (5) | −0.0010 (5) | 0.0005 (5) |
O1—C1 | 1.3704 (14) | C11—C12 | 1.3984 (17) |
O1—C4 | 1.3758 (15) | C12—C13 | 1.3916 (18) |
F1—C2 | 1.3546 (14) | C12—H12 | 0.966 (17) |
C1—C2 | 1.3578 (18) | C13—C14 | 1.388 (2) |
C1—C5 | 1.4537 (17) | C13—H13 | 0.984 (18) |
C2—C3 | 1.4219 (17) | C14—C15 | 1.386 (2) |
C3—C4 | 1.3743 (18) | C14—H14 | 0.977 (17) |
C3—C11 | 1.4753 (17) | C15—C16 | 1.3866 (19) |
C4—C17 | 1.4631 (17) | C15—H15 | 0.959 (19) |
C5—C6 | 1.3984 (18) | C16—H16 | 0.964 (17) |
C5—C10 | 1.3993 (19) | C17—C18 | 1.3993 (18) |
C6—C7 | 1.394 (2) | C17—C22 | 1.4002 (18) |
C6—H6 | 0.958 (17) | C18—C19 | 1.3892 (19) |
C7—C8 | 1.383 (2) | C18—H18 | 1.005 (18) |
C7—H7 | 0.959 (19) | C19—C20 | 1.388 (2) |
C8—C9 | 1.384 (2) | C19—H19 | 0.965 (18) |
C8—H8 | 1.01 (2) | C20—C21 | 1.391 (2) |
C9—C10 | 1.3849 (19) | C20—H20 | 0.932 (18) |
C9—H9 | 1.004 (19) | C21—C22 | 1.3879 (18) |
C10—H10 | 0.999 (18) | C21—H21 | 0.961 (17) |
C11—C16 | 1.3976 (18) | C22—H22 | 0.973 (17) |
C1—O1—C4 | 108.65 (10) | C13—C12—C11 | 120.29 (12) |
C2—C1—O1 | 106.75 (10) | C13—C12—H12 | 121.0 (10) |
C2—C1—C5 | 134.32 (11) | C11—C12—H12 | 118.7 (10) |
O1—C1—C5 | 118.87 (11) | C14—C13—C12 | 120.53 (12) |
F1—C2—C1 | 124.99 (11) | C14—C13—H13 | 119.6 (10) |
F1—C2—C3 | 124.36 (11) | C12—C13—H13 | 119.8 (10) |
C1—C2—C3 | 110.61 (11) | C15—C14—C13 | 119.55 (12) |
C4—C3—C2 | 103.87 (11) | C15—C14—H14 | 119.5 (10) |
C4—C3—C11 | 131.39 (12) | C13—C14—H14 | 120.9 (10) |
C2—C3—C11 | 124.56 (11) | C14—C15—C16 | 120.13 (13) |
C3—C4—O1 | 110.06 (11) | C14—C15—H15 | 121.0 (11) |
C3—C4—C17 | 134.83 (12) | C16—C15—H15 | 118.8 (11) |
O1—C4—C17 | 114.99 (10) | C15—C16—C11 | 120.98 (13) |
C6—C5—C10 | 118.98 (12) | C15—C16—H16 | 120.3 (10) |
C6—C5—C1 | 120.76 (12) | C11—C16—H16 | 118.8 (9) |
C10—C5—C1 | 120.25 (11) | C18—C17—C22 | 119.05 (12) |
C7—C6—C5 | 119.84 (14) | C18—C17—C4 | 119.45 (11) |
C7—C6—H6 | 121.9 (10) | C22—C17—C4 | 121.41 (11) |
C5—C6—H6 | 118.2 (10) | C19—C18—C17 | 120.20 (13) |
C8—C7—C6 | 120.54 (13) | C19—C18—H18 | 120.3 (10) |
C8—C7—H7 | 123.5 (11) | C17—C18—H18 | 119.5 (10) |
C6—C7—H7 | 115.9 (11) | C20—C19—C18 | 120.55 (13) |
C7—C8—C9 | 119.90 (13) | C20—C19—H19 | 120.9 (11) |
C7—C8—H8 | 118.9 (11) | C18—C19—H19 | 118.5 (11) |
C9—C8—H8 | 121.2 (11) | C19—C20—C21 | 119.46 (13) |
C10—C9—C8 | 120.18 (14) | C19—C20—H20 | 120.9 (11) |
C10—C9—H9 | 120.7 (11) | C21—C20—H20 | 119.6 (11) |
C8—C9—H9 | 119.1 (11) | C22—C21—C20 | 120.50 (13) |
C9—C10—C5 | 120.55 (13) | C22—C21—H21 | 118.2 (10) |
C9—C10—H10 | 119.6 (10) | C20—C21—H21 | 121.3 (10) |
C5—C10—H10 | 119.9 (10) | C21—C22—C17 | 120.22 (12) |
C16—C11—C12 | 118.47 (12) | C21—C22—H22 | 119.5 (9) |
C16—C11—C3 | 119.46 (11) | C17—C22—H22 | 120.2 (9) |
C12—C11—C3 | 121.96 (11) | ||
C4—O1—C1—C2 | 0.17 (13) | C6—C5—C10—C9 | 0.3 (2) |
C4—O1—C1—C5 | −177.28 (10) | C1—C5—C10—C9 | 178.98 (12) |
O1—C1—C2—F1 | −179.54 (11) | C4—C3—C11—C16 | 144.23 (14) |
C5—C1—C2—F1 | −2.7 (2) | C2—C3—C11—C16 | −41.45 (18) |
O1—C1—C2—C3 | −1.62 (15) | C4—C3—C11—C12 | −39.9 (2) |
C5—C1—C2—C3 | 175.24 (13) | C2—C3—C11—C12 | 134.45 (13) |
F1—C2—C3—C4 | −179.66 (11) | C16—C11—C12—C13 | −1.74 (18) |
C1—C2—C3—C4 | 2.40 (14) | C3—C11—C12—C13 | −177.69 (11) |
F1—C2—C3—C11 | 4.7 (2) | C11—C12—C13—C14 | −0.17 (19) |
C1—C2—C3—C11 | −173.21 (12) | C12—C13—C14—C15 | 1.6 (2) |
C2—C3—C4—O1 | −2.26 (13) | C13—C14—C15—C16 | −1.1 (2) |
C11—C3—C4—O1 | 172.92 (12) | C14—C15—C16—C11 | −0.9 (2) |
C2—C3—C4—C17 | 173.25 (13) | C12—C11—C16—C15 | 2.27 (19) |
C11—C3—C4—C17 | −11.6 (2) | C3—C11—C16—C15 | 178.31 (12) |
C1—O1—C4—C3 | 1.40 (13) | C3—C4—C17—C18 | 165.26 (14) |
C1—O1—C4—C17 | −175.10 (10) | O1—C4—C17—C18 | −19.39 (16) |
C2—C1—C5—C6 | 10.0 (2) | C3—C4—C17—C22 | −18.1 (2) |
O1—C1—C5—C6 | −173.47 (12) | O1—C4—C17—C22 | 157.30 (11) |
C2—C1—C5—C10 | −168.72 (14) | C22—C17—C18—C19 | 0.91 (19) |
O1—C1—C5—C10 | 7.86 (18) | C4—C17—C18—C19 | 177.67 (12) |
C10—C5—C6—C7 | −0.2 (2) | C17—C18—C19—C20 | 0.0 (2) |
C1—C5—C6—C7 | −178.92 (12) | C18—C19—C20—C21 | −0.5 (2) |
C5—C6—C7—C8 | 0.0 (2) | C19—C20—C21—C22 | 0.0 (2) |
C6—C7—C8—C9 | 0.3 (2) | C20—C21—C22—C17 | 0.9 (2) |
C7—C8—C9—C10 | −0.2 (2) | C18—C17—C22—C21 | −1.35 (19) |
C8—C9—C10—C5 | −0.1 (2) | C4—C17—C22—C21 | −178.05 (12) |
Experimental details
Crystal data | |
Chemical formula | C22H15FO |
Mr | 314.34 |
Crystal system, space group | Orthorhombic, Pbca |
Temperature (K) | 100 |
a, b, c (Å) | 7.5865 (9), 19.9375 (15), 20.4751 (19) |
V (Å3) | 3097.0 (5) |
Z | 8 |
Radiation type | Mo Kα |
µ (mm−1) | 0.09 |
Crystal size (mm) | 0.41 × 0.38 × 0.35 |
Data collection | |
Diffractometer | Bruker SMART APEX |
Absorption correction | Multi-scan (SADABS; Sheldrick, 2001) |
Tmin, Tmax | 0.861, 0.962 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 24875, 3687, 3398 |
Rint | 0.021 |
(sin θ/λ)max (Å−1) | 0.663 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.045, 0.119, 1.06 |
No. of reflections | 3687 |
No. of parameters | 277 |
H-atom treatment | All H-atom parameters refined |
Δρmax, Δρmin (e Å−3) | 0.59, −0.24 |
Computer programs: SMART (Bruker, 2002), SAINT (Bruker, 2002), SHELXS97 (Sheldrick, 1990), SHELXL97 (Sheldrick, 1997), SHELXTL (Bruker, 2001) and ORTEP-3 (Farrugia, 1997), SHELXTL (Bruker, 2001).
The furan ring system is a critical structural moiety of a variety of natural products, active pharmaceuticals, agricultural compounds, and synthetic precursors. One particularly underdeveloped area of furan chemistry is the synthesis of fluorine containing systems. This is exceptionally puzzling due to the interesting pharmokinetic properties fluorine can instill into the parent molecule (Uneyama, 2006; Schlosser, 1998; Hammond, 2005). Recently, our group reported the facile, indium mediated synthesis of α,α-difluorohomopropargyl alcohols (Arimitsu & Hammond, 2006; Arimitsu et al., 2007). The synthetic usefulness of these alcohols in heterocyclizations was demonstrated with a silver catalyzed synthesis of 3-fluoro-2,5-disubstituted furans. If an electrophile could be trapped using this methodology it could provide a critical synthetic handle at the 4-position of the fluorofurans, which in turn could provide ready access to hitherto unknown 3-fluoro-2,4,5-trisubstituted furans such as the title compound.
A search of the Cambridge crystallographic database revealed that the title compound represents the first structurally characterized fully substituted fluorofuran (Allen, 2002). The atomic labelling scheme is shown in Fig. 1 (ORTEP-3, Farrugia, 1997) and a partial packing diagram (Fig. 2) identifies the aromatic rings involved in the intermolecular π stacking analysis (Janiak, 2000). Neighboring five-membered furan rings are involved in two intermolecular π-π stacking interactions along the crystallographic a axis. The first slipped stack interaction between furan rings is 3.61 (4) Å, between C2 at (x, y, z) and the centroid of the five-memebered ring at (x + 0.5. y, 0.5 - z). There is a second slipped π stack interaction of 3.64 (4) Å from C1 at (x + 0.5. y, 0.5 - z) to the centroid of the furan ring at (x, y, z). There are also two slipped π stack intermolecular interactions formed between the phenyl group containing C5—C10 (Ph1) at (x, y, z) with the phenyl group containing C17—C22 (Ph3) of the neighboring molecule at (x + 0.5. y, 0.5 - z). The intermolecular C7 (x, y, z) to C17—C22 centroid distance is 3.53 (4) Å. The second intermolecular interaction of 3.64 (4) Å is between C17 (x + 0.5. y, 0.5 - z) and the C5—C10 centroid.
The fluorine atom sits (dev 0.007 (1) Å) in the same plane as the furan ring, which has a mean deviation of 0.009 (1) Å. The F1—H6 non-bonded contact is 2.416 (17) Å with a F1···C6 separation of 3.0814 (17) Å and the C6—H6···F1 angle is 126.3 (4)°. The O1···H10 non-bonded contact is 2.491 (17) Å with a O1···C10 separation of 2.8250 (16) Å and the C10—H10···O1 angle is 99.0 (4)°. Neither is representative of a classical intramolecular hydrogen bond (Desiraju, 1995). It is however noteworthy that the C5—C10 phenyl plane (dev 0.001 (1) Å), located between F1 and O1, is only 9.55 (7)° from being coplanar with the furan ring, whereas the C11—C16 (dev 0.008 (1) Å) and the C17—C22 (dev 0.004 (1) Å) aromatic planes form angles of 41.71° and 20.45°, respectively, with the five-membered furan ring. The X-ray structure of the related complex 3-fluoro-2-(4-methoxyphenyl)-5-phenylfuran previously reported (Xu & Chen, 2003; CSD refcode HACYUG) contains two aromatic substiuents and shows similar π stacking interactions to the title compound. Interestingly, the methoxyphenyl group located at position 2 of the furan ring in this compound is also nearly coplanar (angle of 1.99°) with the furan plane. The fact that the only two crystal structures known for fluorofurans both show this coplanarity may suggest the possibility of an F···H interaction, but this needs to be proven with more structurally related analogues.