Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536807048106/kp2137sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S1600536807048106/kp2137Isup2.hkl |
CCDC reference: 667320
The compound was prepared by the reduction of 2-hydroxy-1,2-bis(5-methylfuran-2-yl)ethanone to the corresponding 1,2-diol and propargylation of the latter with propargyl bromide in the presence of a base as described in the literature (Hashmi, Wölfle et al., 2007). The two diastereomers were separated by column chromatography on silica gel (PE–EtOAc–CH2Cl2, 30:1:2) as described there, the diastereomer eluting first crystallized by slow evaporation from a chloroform solution. 1H NMR spectroscopic data of the pure diastereomer: 1H NMR (300 MHz, CDCl3): d = 2.30 (d, J = 1.0 Hz, 6 H), 2.36 (t, J = 2.4 Hz, 2 H), 3.93 (dd, J = 15.9, 2.4 Hz, 2 H), 4.08 (dd, J = 15.9, 2.4 Hz, 2 H), 4.91 (s, 2 H), 5.95 (dq, J = 3.1, 1.0 Hz, 2 H), 6.33 (d, J = 3.1 Hz, 2 H).
H atoms were located in difference Fourier map and refined with fixed individual displacement parameters [U(H) = 1.2Ueq(C) or U(H) = 1.5Ueq (Cmethyl)] using a riding model with C—H ranging from 0.93 to 0.97 A°. In addition, the methyl group was allowed to rotate but not to tip.
In the course of the investigation of the synthetic potential of fufural derivatives as renewable feedstocks (Hashmi et al., 2006; Hashmi, Ata et al., 2007) we investigated their possible transformation into bis-phenols in the gold-catalyzed phenol synthesis (Hashmi et al., 2000), one of the numerous gold-catalyzed cycloisomerization reactions known today (Hashmi, 2004; Hashmi & Hutchings, 2006a,b; Hashmi, 2007). This crystal structure analyis now allows a unambiguous assignment of the different diastereomers formed in previous step, the organo-catalyzed benzoin condensation of fufurals, and in the subsequent step, the gold-catalyzed synthesis of the benzoid arene ring.
The molecule crystallizes with a half of the molecule in the asymmetric unit (Fig. 1). The inversion centre located in the midd of C6—C6A (-x + 2, -y + 1, -z + 1) generates the molecule having the chiral centres of opposite chirality, characteristic of a meso-form. The perfect coplanar orientation of the two symmetry-related furan rings is indicated by the angle of their best planes of 0.00 (12)°. The alkynyl moieties shows a parallel orientation to the best plane of the furan moieties with an angle of 2.48 (19)°. The triple bond C8≡C9 is clearly characterized by the distance of 1.174 (3) A°. The packing diagram (Fig. 2) shows a linear intermolecular C9—H9···O2 contact with a H9···O2 distance of 2.39 Å between the alkynyl moiety and the ether function. A weak intermolecular C3—H3···O1 interaction with a H3···O1 distance of 2.87 Å between neighboring furan moieties along the direction of the c axis is observed.
For related literature, see: Hashmi (2004, 2007); Hashmi & Hutchings (2006a, 2006b); Hashmi et al. (2000); Hashmi, Ata et al. (2007); Hashmi et al. (2006); Hashmi, Wölfle et al. (2007).
Data collection: P3/PC Data Collection Software (Siemens, 1991); cell refinement: P3/PC Data Collection Software (Siemens, 1991); data reduction: XDISK in SHELXTL-Plus (Sheldrick, 1991); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: XP in SHELXTL-Plus (Sheldrick, 1991); software used to prepare material for publication: SHELXL97 (Sheldrick, 1997) and PLATON (Spek, 2003).
Fig. 1. The ORTEP drawing of (I) with atom numbering. Displacement ellipsoids are at the 50% probability level. | |
Fig. 2. Packing diagram (I) along the a axis. |
C18H18O4 | F(000) = 316 |
Mr = 298.32 | Dx = 1.241 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ybc | Cell parameters from 26 reflections |
a = 7.945 (4) Å | θ = 16–18° |
b = 9.215 (5) Å | µ = 0.09 mm−1 |
c = 11.408 (5) Å | T = 293 K |
β = 107.17 (4)° | Block, colourless |
V = 798.1 (7) Å3 | 0.9 × 0.8 × 0.5 mm |
Z = 2 |
Nicolet P3 diffractometer | Rint = 0.048 |
Radiation source: fine-focus sealed tube | θmax = 25.0°, θmin = 2.7° |
Graphite monochromator | h = 0→9 |
Wyckoff scan | k = 0→10 |
1506 measured reflections | l = −13→12 |
1402 independent reflections | 3 standard reflections every 50 reflections |
1204 reflections with I > 2σ(I) | intensity decay: 3% |
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)] = 0.048 | H-atom parameters constrained |
wR(F2) = 0.129 | w = 1/[σ2(Fo2) + (0.07P)2 + 0.237P] where P = (Fo2 + 2Fc2)/3 |
S = 1.06 | (Δ/σ)max < 0.001 |
1402 reflections | Δρmax = 0.22 e Å−3 |
102 parameters | Δρmin = −0.21 e Å−3 |
0 restraints | Extinction correction: SHELXL97 (Sheldrick, 1997), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.019 (5) |
C18H18O4 | V = 798.1 (7) Å3 |
Mr = 298.32 | Z = 2 |
Monoclinic, P21/c | Mo Kα radiation |
a = 7.945 (4) Å | µ = 0.09 mm−1 |
b = 9.215 (5) Å | T = 293 K |
c = 11.408 (5) Å | 0.9 × 0.8 × 0.5 mm |
β = 107.17 (4)° |
Nicolet P3 diffractometer | Rint = 0.048 |
1506 measured reflections | 3 standard reflections every 50 reflections |
1402 independent reflections | intensity decay: 3% |
1204 reflections with I > 2σ(I) |
R[F2 > 2σ(F2)] = 0.048 | 0 restraints |
wR(F2) = 0.129 | H-atom parameters constrained |
S = 1.06 | Δρmax = 0.22 e Å−3 |
1402 reflections | Δρmin = −0.21 e Å−3 |
102 parameters |
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. |
Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger. |
x | y | z | Uiso*/Ueq | ||
O1 | 0.83398 (16) | 0.25136 (13) | 0.46359 (11) | 0.0466 (4) | |
C1 | 0.7962 (2) | 0.1247 (2) | 0.39765 (18) | 0.0487 (5) | |
O2 | 0.78036 (15) | 0.56861 (13) | 0.46974 (11) | 0.0456 (4) | |
C2 | 0.8173 (2) | 0.1443 (2) | 0.28653 (17) | 0.0509 (5) | |
H2 | 0.8003 | 0.0751 | 0.2247 | 0.061* | |
C3 | 0.8704 (2) | 0.2904 (2) | 0.28085 (16) | 0.0485 (5) | |
H3 | 0.8947 | 0.3353 | 0.2147 | 0.058* | |
C4 | 0.8788 (2) | 0.35128 (19) | 0.38888 (15) | 0.0413 (4) | |
C5 | 0.7412 (3) | 0.0006 (2) | 0.4606 (2) | 0.0710 (7) | |
H5A | 0.7008 | −0.0772 | 0.4032 | 0.107* | |
H5B | 0.6476 | 0.0307 | 0.4925 | 0.107* | |
H5C | 0.8395 | −0.0319 | 0.5267 | 0.107* | |
C6 | 0.9246 (2) | 0.49899 (18) | 0.44007 (15) | 0.0396 (4) | |
H6 | 0.9583 | 0.5583 | 0.3793 | 0.048* | |
C7 | 0.6267 (2) | 0.5851 (2) | 0.36739 (17) | 0.0502 (5) | |
H7A | 0.5355 | 0.6319 | 0.3946 | 0.060* | |
H7B | 0.5840 | 0.4897 | 0.3365 | 0.060* | |
C8 | 0.6578 (2) | 0.6704 (2) | 0.26747 (17) | 0.0496 (5) | |
C9 | 0.6892 (3) | 0.7371 (2) | 0.1888 (2) | 0.0602 (6) | |
H9 | 0.7140 | 0.7900 | 0.1264 | 0.072* |
U11 | U22 | U33 | U12 | U13 | U23 | |
O1 | 0.0517 (8) | 0.0455 (7) | 0.0437 (7) | −0.0066 (5) | 0.0158 (6) | −0.0024 (5) |
C1 | 0.0430 (10) | 0.0440 (10) | 0.0570 (11) | −0.0058 (8) | 0.0117 (8) | −0.0089 (8) |
O2 | 0.0399 (7) | 0.0523 (8) | 0.0448 (7) | 0.0035 (5) | 0.0126 (5) | −0.0032 (5) |
C2 | 0.0436 (10) | 0.0540 (11) | 0.0542 (11) | −0.0057 (8) | 0.0128 (8) | −0.0184 (9) |
C3 | 0.0447 (10) | 0.0607 (12) | 0.0416 (9) | −0.0033 (8) | 0.0151 (8) | −0.0047 (8) |
C4 | 0.0368 (9) | 0.0472 (10) | 0.0398 (9) | −0.0017 (7) | 0.0111 (7) | 0.0016 (7) |
C5 | 0.0828 (15) | 0.0524 (12) | 0.0795 (15) | −0.0167 (11) | 0.0265 (12) | −0.0043 (11) |
C6 | 0.0382 (9) | 0.0420 (9) | 0.0401 (9) | −0.0010 (7) | 0.0139 (7) | 0.0016 (7) |
C7 | 0.0393 (9) | 0.0547 (11) | 0.0539 (11) | −0.0004 (8) | 0.0099 (8) | −0.0017 (8) |
C8 | 0.0455 (10) | 0.0491 (10) | 0.0497 (10) | 0.0056 (8) | 0.0071 (8) | −0.0033 (9) |
C9 | 0.0651 (13) | 0.0583 (12) | 0.0547 (12) | 0.0050 (10) | 0.0139 (10) | 0.0053 (10) |
O1—C4 | 1.371 (2) | C5—H5A | 0.9600 |
O1—C1 | 1.373 (2) | C5—H5B | 0.9600 |
C1—C2 | 1.339 (3) | C5—H5C | 0.9600 |
C1—C5 | 1.483 (3) | C6—C6i | 1.529 (3) |
O2—C7 | 1.427 (2) | C6—H6 | 0.9800 |
O2—C6 | 1.438 (2) | C7—C8 | 1.464 (3) |
C2—C3 | 1.418 (3) | C7—H7A | 0.9700 |
C2—H2 | 0.9300 | C7—H7B | 0.9700 |
C3—C4 | 1.338 (2) | C8—C9 | 1.174 (3) |
C3—H3 | 0.9300 | C9—H9 | 0.9300 |
C4—C6 | 1.484 (2) | ||
C4—O1—C1 | 106.57 (14) | C1—C5—H5C | 109.5 |
C2—C1—O1 | 109.62 (17) | H5A—C5—H5C | 109.5 |
C2—C1—C5 | 134.38 (19) | H5B—C5—H5C | 109.5 |
O1—C1—C5 | 115.99 (17) | O2—C6—C4 | 112.45 (14) |
C7—O2—C6 | 113.80 (13) | O2—C6—C6i | 104.63 (16) |
C1—C2—C3 | 107.06 (16) | C4—C6—C6i | 113.56 (17) |
C1—C2—H2 | 126.5 | O2—C6—H6 | 108.7 |
C3—C2—H2 | 126.5 | C4—C6—H6 | 108.7 |
C4—C3—C2 | 106.91 (16) | C6i—C6—H6 | 108.7 |
C4—C3—H3 | 126.5 | O2—C7—C8 | 113.20 (15) |
C2—C3—H3 | 126.5 | O2—C7—H7A | 108.9 |
C3—C4—O1 | 109.85 (16) | C8—C7—H7A | 108.9 |
C3—C4—C6 | 133.41 (16) | O2—C7—H7B | 108.9 |
O1—C4—C6 | 116.74 (14) | C8—C7—H7B | 108.9 |
C1—C5—H5A | 109.5 | H7A—C7—H7B | 107.8 |
C1—C5—H5B | 109.5 | C9—C8—C7 | 177.5 (2) |
H5A—C5—H5B | 109.5 | C8—C9—H9 | 180.0 |
C4—O1—C1—C2 | 0.27 (19) | C1—O1—C4—C6 | 179.62 (14) |
C4—O1—C1—C5 | −179.11 (17) | C7—O2—C6—C4 | −59.43 (18) |
O1—C1—C2—C3 | −0.2 (2) | C7—O2—C6—C6i | 176.88 (15) |
C5—C1—C2—C3 | 179.0 (2) | C3—C4—C6—O2 | 118.0 (2) |
C1—C2—C3—C4 | 0.1 (2) | O1—C4—C6—O2 | −61.82 (19) |
C2—C3—C4—O1 | 0.1 (2) | C3—C4—C6—C6i | −123.5 (2) |
C2—C3—C4—C6 | −179.71 (18) | O1—C4—C6—C6i | 56.7 (2) |
C1—O1—C4—C3 | −0.22 (19) | C6—O2—C7—C8 | −59.1 (2) |
Symmetry code: (i) −x+2, −y+1, −z+1. |
D—H···A | D—H | H···A | D···A | D—H···A |
C9—H9···O2ii | 0.93 | 2.39 | 3.323 (3) | 179 |
C3—H3···O1iii | 0.93 | 2.87 | 3.566 (3) | 132 |
Symmetry codes: (ii) x, −y+3/2, z−1/2; (iii) x, −y+1/2, z−1/2. |
Experimental details
Crystal data | |
Chemical formula | C18H18O4 |
Mr | 298.32 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 293 |
a, b, c (Å) | 7.945 (4), 9.215 (5), 11.408 (5) |
β (°) | 107.17 (4) |
V (Å3) | 798.1 (7) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 0.09 |
Crystal size (mm) | 0.9 × 0.8 × 0.5 |
Data collection | |
Diffractometer | Nicolet P3 |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 1506, 1402, 1204 |
Rint | 0.048 |
(sin θ/λ)max (Å−1) | 0.594 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.048, 0.129, 1.06 |
No. of reflections | 1402 |
No. of parameters | 102 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.22, −0.21 |
Computer programs: P3/PC Data Collection Software (Siemens, 1991), XDISK in SHELXTL-Plus (Sheldrick, 1991), SHELXS97 (Sheldrick, 1997), XP in SHELXTL-Plus (Sheldrick, 1991), SHELXL97 (Sheldrick, 1997) and PLATON (Spek, 2003).
D—H···A | D—H | H···A | D···A | D—H···A |
C9—H9···O2i | 0.93 | 2.39 | 3.323 (3) | 178.5 |
C3—H3···O1ii | 0.93 | 2.87 | 3.566 (3) | 132.2 |
Symmetry codes: (i) x, −y+3/2, z−1/2; (ii) x, −y+1/2, z−1/2. |
In the course of the investigation of the synthetic potential of fufural derivatives as renewable feedstocks (Hashmi et al., 2006; Hashmi, Ata et al., 2007) we investigated their possible transformation into bis-phenols in the gold-catalyzed phenol synthesis (Hashmi et al., 2000), one of the numerous gold-catalyzed cycloisomerization reactions known today (Hashmi, 2004; Hashmi & Hutchings, 2006a,b; Hashmi, 2007). This crystal structure analyis now allows a unambiguous assignment of the different diastereomers formed in previous step, the organo-catalyzed benzoin condensation of fufurals, and in the subsequent step, the gold-catalyzed synthesis of the benzoid arene ring.
The molecule crystallizes with a half of the molecule in the asymmetric unit (Fig. 1). The inversion centre located in the midd of C6—C6A (-x + 2, -y + 1, -z + 1) generates the molecule having the chiral centres of opposite chirality, characteristic of a meso-form. The perfect coplanar orientation of the two symmetry-related furan rings is indicated by the angle of their best planes of 0.00 (12)°. The alkynyl moieties shows a parallel orientation to the best plane of the furan moieties with an angle of 2.48 (19)°. The triple bond C8≡C9 is clearly characterized by the distance of 1.174 (3) A°. The packing diagram (Fig. 2) shows a linear intermolecular C9—H9···O2 contact with a H9···O2 distance of 2.39 Å between the alkynyl moiety and the ether function. A weak intermolecular C3—H3···O1 interaction with a H3···O1 distance of 2.87 Å between neighboring furan moieties along the direction of the c axis is observed.