Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270199016923/fr1229sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270199016923/fr1229Isup2.hkl |
CCDC reference: 144633
Flavone (2.50 g, 0.0113 mol), obtained by the Baker-Venkataraman method (reference?), was added slowly with stirring to chlorosulfonic acid (25 ml, 0.376 mol), cooled to 263 K in an ice-salt bath. The reaction mixture was stirred for 2 d at room temperature and was then poured into iced water. The crude sulfonylchloride (1.40 g, 4.37 mmol) was treated with aqueous ammonia (100 ml) and stirred for 3 h at 273 K, and flavone-3'-sulfonamide, (I), was obtained by removing the excess ammonia under reduced pressure. The crude product was crystallized from ethanol-dimethylsulfoxide (10:1) (yield: 1.10 g, 83.66%; m.p. 481–483 K). Spectrosopic analysis: 1H NMR (DMSO-d6, 400 MHz, δ, p.p.m.): 7.10 (s, 1H, 3-H), 7.52 (ddd, 1H, 6-H), 7.76–7.85 (m, 3H, 7-H, 4'-H, 6'-H), 7.98 (d, 1H, 8-H), 8.05 (dd, 1H, 5'-H), 8.28 (d, 1H, 5-H), 8.48 (s, 1H, 2'-H); mass spectrosopy (70 eV), m/e: 301 (M+), 302 (M+1), 303 (M+2), 221, 193, 121, 120, 101, 92 (%100), 64, 63; IR, cm-1: 1614 (γ-pyrone C=O).
H atoms were placed geometrically 0.95 Å from their parent atoms. Atoms H1N and H2N were refined for a few cycles with isotropic parameters and then for all H atoms a riding model was used with Ueq(H) = 1.3Ueq(C).
Data collection: CAD-4 EXPRESS (Enraf-Nonius, 1993); cell refinement: CAD-4 EXPRESS; data reduction: MolEN (Fair, 1990); program(s) used to solve structure: MolEN and PARST (Nardelli, 1995); program(s) used to refine structure: MolEN; molecular graphics: ORTEPII (Johnson, 1976); software used to prepare material for publication: MolEN.
C15H11NO4S | V = 653.6 (2) Å3 |
Mr = 301.32 | Z = 2 |
Triclinic, P1 | Dx = 1.531 Mg m−3 |
Hall symbol: -P 1 | Mo Kα radiation, λ = 0.71069 Å |
a = 8.6654 (5) Å | Cell parameters from 25 reflections |
b = 8.7898 (6) Å | θ = 9.4–18.2° |
c = 10.0105 (6) Å | µ = 0.26 mm−1 |
α = 98.183 (7)° | T = 295 K |
β = 112.991 (6)° | Prismatic, colourless |
γ = 104.673 (6)° | 0.56 × 0.40 × 0.20 mm |
Enraf-Nonius CAD-4 diffractometer | Rint = 0.010 |
ω/2θ scans | θmax = 26.3°, θmin = 2.4° |
Absorption correction: empirical (using intensity measurements) via ψ scans (North et al., 1968) | h = −10→0 |
Tmin = 0.869, Tmax = 0.951 | k = −10→10 |
2834 measured reflections | l = −11→12 |
2649 independent reflections | 3 standard reflections every 120 min |
2057 reflections with I > 2σ(I) | intensity decay: 1.5% |
Refinement on F | H atoms treated by a mixture of independent and constrained refinement |
R[F2 > 2σ(F2)] = 0.037 | Calculated w = 1/[σF2] |
wR(F2) = 0.044 | (Δ/σ)max < 0.001 |
S = 0.90 | Δρmax = 0.23 e Å−3 |
2057 reflections | Δρmin = −0.09 e Å−3 |
192 parameters |
C15H11NO4S | γ = 104.673 (6)° |
Mr = 301.32 | V = 653.6 (2) Å3 |
Triclinic, P1 | Z = 2 |
a = 8.6654 (5) Å | Mo Kα radiation |
b = 8.7898 (6) Å | µ = 0.26 mm−1 |
c = 10.0105 (6) Å | T = 295 K |
α = 98.183 (7)° | 0.56 × 0.40 × 0.20 mm |
β = 112.991 (6)° |
Enraf-Nonius CAD-4 diffractometer | 2057 reflections with I > 2σ(I) |
Absorption correction: empirical (using intensity measurements) via ψ scans (North et al., 1968) | Rint = 0.010 |
Tmin = 0.869, Tmax = 0.951 | 3 standard reflections every 120 min |
2834 measured reflections | intensity decay: 1.5% |
2649 independent reflections |
R[F2 > 2σ(F2)] = 0.037 | 192 parameters |
wR(F2) = 0.044 | H atoms treated by a mixture of independent and constrained refinement |
S = 0.90 | Δρmax = 0.23 e Å−3 |
2057 reflections | Δρmin = −0.09 e Å−3 |
x | y | z | Uiso*/Ueq | ||
S1 | 0.82621 (6) | 0.30717 (6) | 0.67645 (5) | 0.0414 (2) | |
O1 | 0.4636 (2) | 0.8412 (2) | 0.7244 (1) | 0.0424 (4) | |
O2 | 0.2693 (2) | 0.6172 (2) | 0.9823 (2) | 0.0490 (5) | |
O3 | 0.9381 (2) | 0.2958 (2) | 0.6044 (2) | 0.0587 (5) | |
O4 | 0.6645 (2) | 0.1769 (2) | 0.6315 (2) | 0.0577 (6) | |
N1 | 0.9434 (2) | 0.3320 (2) | 0.8538 (2) | 0.0455 (6) | |
C2 | 0.4998 (2) | 0.7079 (2) | 0.7602 (2) | 0.0348 (5) | |
C3 | 0.4359 (2) | 0.6304 (2) | 0.8441 (2) | 0.0407 (6) | |
C4 | 0.3287 (2) | 0.6884 (2) | 0.9043 (2) | 0.0379 (6) | |
C5 | 0.1996 (2) | 0.9128 (3) | 0.9216 (2) | 0.0470 (7) | |
C6 | 0.1700 (3) | 1.0478 (3) | 0.8811 (3) | 0.0544 (7) | |
C7 | 0.2352 (3) | 1.1122 (3) | 0.7871 (3) | 0.0542 (8) | |
C8 | 0.3328 (3) | 1.0418 (3) | 0.7347 (2) | 0.0490 (7) | |
C9 | 0.3626 (2) | 0.9044 (2) | 0.7775 (2) | 0.0390 (6) | |
C10 | 0.2968 (2) | 0.8352 (2) | 0.8687 (2) | 0.0367 (6) | |
C11 | 0.6187 (2) | 0.6659 (2) | 0.6996 (2) | 0.0349 (6) | |
C12 | 0.6943 (2) | 0.7709 (2) | 0.6321 (2) | 0.0409 (7) | |
C13 | 0.8085 (2) | 0.7332 (3) | 0.5782 (2) | 0.0447 (6) | |
C14 | 0.8491 (2) | 0.5918 (3) | 0.5905 (2) | 0.0426 (6) | |
C15 | 0.7736 (2) | 0.4878 (2) | 0.6566 (2) | 0.0364 (6) | |
C16 | 0.6582 (2) | 0.5234 (2) | 0.7108 (2) | 0.0371 (5) | |
H3 | 0.462 | 0.535 | 0.864 | 0.0519* | |
H5 | 0.154 | 0.870 | 0.986 | 0.0596* | |
H6 | 0.104 | 1.098 | 0.917 | 0.0672* | |
H7 | 0.213 | 1.206 | 0.759 | 0.0685* | |
H8 | 0.378 | 1.085 | 0.671 | 0.0621* | |
H12 | 0.667 | 0.868 | 0.623 | 0.0532* | |
H13 | 0.860 | 0.805 | 0.533 | 0.0583* | |
H14 | 0.928 | 0.566 | 0.554 | 0.0545* | |
H16 | 0.606 | 0.450 | 0.755 | 0.0482* | |
H1N | 1.053 | 0.418 | 0.890 | 0.0609* | |
H2N | 0.864 | 0.336 | 0.896 | 0.0761* |
U11 | U22 | U33 | U12 | U13 | U23 | |
S1 | 0.0517 (2) | 0.0420 (2) | 0.0527 (2) | 0.0272 (1) | 0.0384 (1) | 0.0186 (2) |
O1 | 0.0550 (5) | 0.0489 (6) | 0.0541 (5) | 0.0339 (4) | 0.0411 (4) | 0.0283 (5) |
O2 | 0.0634 (5) | 0.0525 (7) | 0.0643 (6) | 0.0289 (5) | 0.0511 (4) | 0.0285 (5) |
O3 | 0.0806 (5) | 0.0672 (7) | 0.0725 (6) | 0.0496 (5) | 0.0625 (4) | 0.0327 (6) |
O4 | 0.0595 (7) | 0.0412 (7) | 0.0793 (9) | 0.0178 (6) | 0.0385 (6) | 0.0150 (7) |
N1 | 0.0528 (6) | 0.0505 (8) | 0.0570 (7) | 0.0293 (5) | 0.0384 (5) | 0.0246 (6) |
C2 | 0.0392 (6) | 0.0378 (8) | 0.0394 (7) | 0.0205 (6) | 0.0244 (5) | 0.0155 (6) |
C3 | 0.0506 (7) | 0.0420 (8) | 0.0534 (8) | 0.0266 (6) | 0.0376 (5) | 0.0229 (7) |
C4 | 0.0407 (7) | 0.0428 (9) | 0.0431 (7) | 0.0184 (6) | 0.0280 (5) | 0.0160 (7) |
C5 | 0.0497 (7) | 0.054 (1) | 0.0569 (9) | 0.0275 (6) | 0.0378 (6) | 0.0194 (8) |
C6 | 0.0582 (8) | 0.057 (1) | 0.067 (1) | 0.0369 (6) | 0.0403 (6) | 0.0185 (9) |
C7 | 0.0628 (9) | 0.0517 (9) | 0.069 (1) | 0.0379 (7) | 0.0376 (7) | 0.0273 (8) |
C8 | 0.0599 (8) | 0.0530 (9) | 0.0599 (9) | 0.0350 (7) | 0.0388 (6) | 0.0296 (8) |
C9 | 0.0401 (7) | 0.0452 (9) | 0.0442 (8) | 0.0244 (6) | 0.0261 (5) | 0.0156 (7) |
C10 | 0.0355 (6) | 0.0418 (8) | 0.0406 (8) | 0.0181 (6) | 0.0231 (5) | 0.0116 (7) |
C11 | 0.0379 (6) | 0.0412 (8) | 0.0377 (7) | 0.0201 (6) | 0.0247 (5) | 0.0149 (6) |
C12 | 0.0484 (7) | 0.0418 (8) | 0.0505 (8) | 0.0232 (6) | 0.0320 (6) | 0.0217 (7) |
C13 | 0.0514 (7) | 0.051 (1) | 0.0591 (8) | 0.0236 (7) | 0.0417 (5) | 0.0283 (7) |
C14 | 0.0463 (7) | 0.0511 (9) | 0.0512 (8) | 0.0246 (6) | 0.0365 (5) | 0.0200 (7) |
C15 | 0.0420 (7) | 0.0397 (8) | 0.0429 (7) | 0.0221 (6) | 0.0289 (5) | 0.0163 (6) |
C16 | 0.0442 (7) | 0.0406 (8) | 0.0453 (7) | 0.0209 (6) | 0.0324 (5) | 0.0189 (7) |
S1—O3 | 1.431 (2) | C6—C7 | 1.389 (4) |
S1—O4 | 1.423 (2) | C6—H6 | 0.950 |
S1—N1 | 1.613 (2) | C7—C8 | 1.376 (4) |
S1—C15 | 1.776 (2) | C7—H7 | 0.950 |
O1—C2 | 1.348 (3) | C8—C9 | 1.388 (3) |
O1—C9 | 1.373 (3) | C8—H8 | 0.950 |
O2—C4 | 1.247 (3) | C9—C10 | 1.385 (3) |
N1—H1N | 0.946 | C11—C12 | 1.397 (3) |
N1—H2N | 0.942 | C11—C16 | 1.388 (3) |
C2—C3 | 1.346 (3) | C12—C13 | 1.383 (4) |
C2—C11 | 1.478 (3) | C12—H12 | 0.950 |
C3—C4 | 1.440 (3) | C13—C14 | 1.384 (3) |
C3—H3 | 0.950 | C13—H13 | 0.950 |
C4—C10 | 1.451 (3) | C14—C15 | 1.381 (3) |
C5—C6 | 1.360 (4) | C14—H14 | 0.950 |
C5—C10 | 1.411 (3) | C15—C16 | 1.388 (3) |
C5—H5 | 0.950 | C16—H16 | 0.950 |
O3—S1—O4 | 120.1 (1) | C5—C6—C7 | 120.6 (3) |
O3—S1—N1 | 107.3 (9) | C5—C6—H6 | 119.7 |
O3—S1—C15 | 107.2 (1) | C7—C6—H6 | 119.7 |
O4—S1—N1 | 106.3 (1) | C6—C7—C8 | 120.6 (2) |
O4—S1—C15 | 107.9 (1) | C6—C7—H7 | 119.5 |
N1—S1—C15 | 107.3 (1) | C8—C7—H7 | 119.8 |
C2—O1—C9 | 119.9 (2) | C7—C8—C9 | 118.1 (2) |
S1—N1—H1N | 110.0 | C7—C8—H8 | 121.1 |
S1—N1—H2N | 104.4 | C9—C8—H8 | 120.8 |
H1N—N1—H2N | 120.5 | O1—C9—C8 | 115.6 (2) |
O1—C2—C3 | 122.1 (2) | O1—C9—C10 | 121.6 (2) |
O1—C2—C11 | 111.2 (2) | C8—C9—C10 | 122.8 (2) |
C3—C2—C11 | 126.7 (2) | C4—C10—C5 | 123.4 (2) |
C2—C3—C4 | 121.7 (2) | C4—C10—C9 | 119.4 (2) |
C2—C3—H3 | 119.2 | C5—C10—C9 | 117.2 (2) |
C4—C3—H3 | 119.1 | C2—C11—C12 | 120.1 (2) |
O2—C4—C3 | 121.9 (2) | C2—C11—C16 | 120.4 (2) |
O2—C4—C10 | 122.8 (2) | C12—C11—C16 | 119.5 (2) |
C3—C4—C10 | 115.2 (2) | C11—C12—C13 | 120.1 (2) |
C6—C5—C10 | 120.7 (2) | C11—C12—H12 | 119.8 |
C6—C5—H5 | 119.7 | C13—C12—H12 | 120.1 |
C10—C5—H5 | 119.7 | C12—C13—C14 | 120.5 (2) |
C12—C13—H13 | 119.8 | S1—C15—C16 | 118.8 (2) |
C14—C13—H13 | 119.8 | C14—C15—C16 | 121.0 (2) |
C13—C14—C15 | 119.4 (2) | C11—C16—C15 | 119.7 (2) |
C13—C14—H14 | 120.5 | C11—C16—H16 | 120.2 |
C15—C14—H14 | 120.1 | C15—C16—H16 | 120.1 |
S1—C15—C14 | 120.2 (2) | ||
O3—S1—N1—H1N | 50.63 | C5—C6—C7—C8 | −0.8 (4) |
O3—S1—N1—H2N | −178.79 | C5—C6—C7—H7 | 179.58 |
O4—S1—N1—H1N | −179.63 | H6—C6—C7—C8 | 179.39 |
O4—S1—N1—H2N | −49.05 | H6—C6—C7—H7 | −0.21 |
C15—S1—N1—H1N | −64.31 | C6—C7—C8—C9 | 0.5 (3) |
C15—S1—N1—H2N | 66.27 | C6—C7—C8—H8 | −179.82 |
O3—S1—C15—C14 | −4.27 (18) | H7—C7—C8—C9 | −179.88 |
O3—S1—C15—C16 | 176.82 (15) | H7—C7—C8—H8 | −0.22 |
O4—S1—C15—C14 | −135.03 (16) | C7—C8—C9—O1 | −178.80 (19) |
O4—S1—C15—C16 | 46.06 (17) | C7—C8—C9—C10 | 0.7 (3) |
N1—S1—C15—C14 | 110.72 (16) | H8—C8—C9—O1 | 1.54 |
N1—S1—C15—C16 | −68.18 (17) | H8—C8—C9—C10 | −178.93 |
C9—O1—C2—C3 | 1.8 (3) | O1—C9—C10—C4 | −2.6 (3) |
C9—O1—C2—C11 | −176.55 (15) | O1—C9—C10—C5 | 177.88 (17) |
C2—O1—C9—C8 | 179.93 (19) | C8—C9—C10—C4 | 177.92 (19) |
C2—O1—C9—C10 | 0.4 (3) | C8—C9—C10—C5 | −1.6 (3) |
O1—C2—C3—C4 | −1.7 (3) | C2—C11—C12—C13 | 178.69 (18) |
O1—C2—C3—H3 | 178.07 | C2—C11—C12—H12 | −1.61 |
C11—C2—C3—C4 | 176.36 (18) | C16—C11—C12—C13 | −0.5 (3) |
C11—C2—C3—H3 | −3.83 | C16—C11—C12—H12 | 179.22 |
O1—C2—C11—C12 | 7.3 (2) | C2—C11—C16—C15 | −178.45 (17) |
O1—C2—C11—C16 | −173.58 (16) | C2—C11—C16—H16 | 2.03 |
C3—C2—C11—C12 | −171.01 (19) | C12—C11—C16—C15 | 0.7 (3) |
C3—C2—C11—C16 | 8.2 (3) | C12—C11—C16—H16 | −178.80 |
C2—C3—C4—O2 | −179.9 (2) | C11—C12—C13—C14 | −0.1 (3) |
C2—C3—C4—C10 | −0.5 (3) | C11—C12—C13—H13 | −179.65 |
H3—C3—C4—O2 | 0.27 | H12—C12—C13—C14 | −179.78 |
H3—C3—C4—C10 | 179.74 | H12—C12—C13—H13 | 0.66 |
O2—C4—C10—C5 | 1.5 (3) | C12—C13—C14—C15 | 0.4 (3) |
O2—C4—C10—C9 | −178.02 (18) | C12—C13—C14—H14 | −179.62 |
C3—C4—C10—C5 | −177.97 (19) | H13—C13—C14—C15 | 179.95 |
C3—C4—C10—C9 | 2.5 (3) | H13—C13—C14—H14 | −0.06 |
C10—C5—C6—C7 | −0.1 (3) | C13—C14—C15—S1 | −179.03 (15) |
C10—C5—C6—H6 | 179.67 | C13—C14—C15—C16 | −0.1 (3) |
H5—C5—C6—C7 | −179.96 | H14—C14—C15—S1 | 0.99 |
H5—C5—C6—H6 | −0.17 | H14—C14—C15—C16 | 179.87 |
C6—C5—C10—C4 | −178.2 (2) | S1—C15—C16—C11 | 178.48 (14) |
C6—C5—C10—C9 | 1.3 (3) | S1—C15—C16—H16 | −2.00 |
H5—C5—C10—C4 | 1.61 | C14—C15—C16—C11 | −0.4 (3) |
H5—C5—C10—C9 | −178.86 | C14—C15—C16—H16 | 179.11 |
D—H···A | D—H | H···A | D···A | D—H···A |
C5—H5···O2 | 0.95 | 2.659 | 2.906 (3) | 95.32 |
C12—H12···O1 | 0.95 | 2.334 | 2.672 (3) | 100.28 |
C14—H14···O3 | 0.95 | 2.513 | 2.902 (3) | 104.59 |
C16—H16···O4 | 0.95 | 2.795 | 3.056 (3) | 96.73 |
C7—H7···O3i | 0.95 | 2.67 | 3.442 (3) | 139 |
C6—H6···N1i | 0.95 | 2.78 | 3.526 (4) | 137 |
C8—H8···O4ii | 0.95 | 2.61 | 3.417 (3) | 144 |
C12—H12···O4ii | 0.95 | 2.71 | 3.643 (3) | 168 |
C12—H12···O4iii | 0.95 | 2.89 | 3.391 (2) | 115 |
N1—H1N···O2iv | 0.95 | 1.99 | 2.928 (3) | 172 |
N1—H2N···O2v | 0.94 | 2.05 | 2.976 (3) | 169 |
Symmetry codes: (i) x−1, y+1, z; (ii) x, y+1, z; (iii) −x+1, −y+1, −z+1; (iv) x+1, y, z; (v) −x+1, −y+1, −z+2. |
Experimental details
Crystal data | |
Chemical formula | C15H11NO4S |
Mr | 301.32 |
Crystal system, space group | Triclinic, P1 |
Temperature (K) | 295 |
a, b, c (Å) | 8.6654 (5), 8.7898 (6), 10.0105 (6) |
α, β, γ (°) | 98.183 (7), 112.991 (6), 104.673 (6) |
V (Å3) | 653.6 (2) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 0.26 |
Crystal size (mm) | 0.56 × 0.40 × 0.20 |
Data collection | |
Diffractometer | Enraf-Nonius CAD-4 diffractometer |
Absorption correction | Empirical (using intensity measurements) via ψ scans (North et al., 1968) |
Tmin, Tmax | 0.869, 0.951 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 2834, 2649, 2057 |
Rint | 0.010 |
(sin θ/λ)max (Å−1) | 0.623 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.037, 0.044, 0.90 |
No. of reflections | 2057 |
No. of parameters | 192 |
No. of restraints | ? |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.23, −0.09 |
Computer programs: CAD-4 EXPRESS (Enraf-Nonius, 1993), CAD-4 EXPRESS, MolEN (Fair, 1990), MolEN and PARST (Nardelli, 1995), MolEN, ORTEPII (Johnson, 1976).
S1—O3 | 1.431 (2) | O1—C9 | 1.373 (3) |
S1—O4 | 1.423 (2) | O2—C4 | 1.247 (3) |
S1—N1 | 1.613 (2) | C2—C3 | 1.346 (3) |
S1—C15 | 1.776 (2) | C2—C11 | 1.478 (3) |
O1—C2 | 1.348 (3) | ||
O3—S1—O4 | 120.1 (1) | C3—C4—C10 | 115.2 (2) |
O3—S1—N1 | 107.3 (9) | O1—C9—C10 | 121.6 (2) |
O3—S1—C15 | 107.2 (1) | ||
O3—S1—C15—C16 | 176.82 (15) | O1—C2—C11—C16 | −173.58 (16) |
O4—S1—C15—C14 | −135.03 (16) | C13—C14—C15—S1 | −179.03 (15) |
N1—S1—C15—C14 | 110.72 (16) |
D—H···A | D—H | H···A | D···A | D—H···A |
C7—H7···O3i | 0.95 | 2.67 | 3.442 (3) | 139 |
C6—H6···N1i | 0.95 | 2.78 | 3.526 (4) | 137 |
C8—H8···O4ii | 0.95 | 2.61 | 3.417 (3) | 144 |
C12—H12···O4ii | 0.95 | 2.71 | 3.643 (3) | 168 |
C12—H12···O4iii | 0.95 | 2.89 | 3.391 (2) | 115 |
N1—H1N···O2iv | 0.95 | 1.99 | 2.928 (3) | 172 |
N1—H2N···O2v | 0.94 | 2.05 | 2.976 (3) | 169 |
Symmetry codes: (i) x−1, y+1, z; (ii) x, y+1, z; (iii) −x+1, −y+1, −z+1; (iv) x+1, y, z; (v) −x+1, −y+1, −z+2. |
Besides the extensive biological activity of flavonoids, this class of compounds exhibits antidiabetic (Hii & Howell, 1985; Basnet et al., 1993; Ragunathan & Sulochana, 1994) and aldose reductase inhibitory activity (Varma & Kinoshita, 1976; Okuda et al., 1984; Aida et al., 1990). Aryl sulfonamides are widely used as starting materials in the synthesis of antidiabetic sulfonylureas (AFECT, 1995). The title compound, (I), is a flavonesulfonamide and was synthesized as a starting material for antidiabetic flavonesulfonylureas. The structure was elucidated by 1H NMR, mass and IR spectroscopic techniques. The X-ray structure was determined in order to establish the conformation of the molecule. \scheme
All bond lengths and angles in (I) are normal. Rings A and B are quite planar: the maximum deviations are 0.009 (2) and 0.004 (1) Å from the ring planes A and B, respectively. The pyrone ring C is distorted (χ2 = 210.2). The angles between rings A and C and B and C are 1.8 (2) and 8.3 (3)°, respectively, showing that the rings A, B and C are coplanar.
In the generally preferred conformation of flavones, the dihedral angle between the phenyl and the γ-pyrone rings is expected to be small, as in the case of (I). This angle is 13.9 (4)° in 2-(2-ethoxycarbonyl-1,4-benzodioxan-7-yl)-4H-1-benzopyran-4-one (Özbey et al., 1997). Another parameter of interest in flavone structures is the bond length between the benzopyrone and phenyl rings. In flavones, the increase in dihedral angle has the effect of increasing the length of this bond to the expected value for an sp2-sp2 single bond. In compound (I), the corresponding C2—C11 bond length is 1.478 (3) Å. In 5-hydroxy-flavone, the dihedral angle is 5.2 (9)° and the C2—C11 bond is 1.465 (4) Å (Shoja, 1990). In 2'-methyl-3'-nitroflavone, these values are 139.8 (2)° and 1.491 (8) Å, respectively (Kendi et al., 1996). The widening of the O1—C9—C10 angle to 121.6 (2)° and the narrowing of the C3—C4—C10 angle to 115.2 (2)° in the γ-pyrone ring may be attributed to the ring strain caused by the neighbouring Csp2—Csp2 atoms.
Atoms S1 and O3 of the sulfonamide group lie close to the plane of ring B, with deviations of 0.032 (1) and 0.045 (1) Å from the plane, respectively. Atoms O4 and N1 are displaced from the least-squares plane of the atoms in ring B by 0.928 (2) and -1.474 (2) Å, respectively.
The sulfonamide group in (I) is involved in intermolecular as well as intramolecular hydrogen bonding. It was proposed by Rossi et al. (1980) that the hydrogen bonds involving O2 would enhance the electron-withdrawing power of the pyrone ring on the phenyl ring, thus giving C2—C11 more double-bond character and forcing coplanarity between rings B and C. The crystal packing shows that the smaller the dihedral angle between the benzopyrone and phenyl rings, the stronger the stacking interactions that occur between adjacent molecules. Details of the hydrogen bonds in (I) are given in Table 2.