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The title compounds, namely 6-methoxy-3,3-dimethyl-3
H-benzo[
f]chromene, C
16H
16O
2, (III), and racemic 3-bromo-2,2,6,6-tetramethyl-3,4-dihydro-2
H,6
H-1,5-dioxatriphenylene, C
20H
21BrO
2, (IV), were both synthesized in one-step regioselective Wittig reactions from substituted 1,2-naphthoquinones. The new ring in both compounds adopts a screw-boat conformation. A single π–π stacking interaction links the molecules of (III) into centrosymmetric dimeric aggregates, and a single C—H
π(arene) hydrogen bond links the molecules of (IV) into centrosymmetric dimers.
Supporting information
CCDC references: 665498; 665499
The 1,2-naphthoquinone precursor, (II), was prepared from commercially available lapachol by the method of Hooker (1892). This product has been shown to be a racemic mixture of enantiomers (De Simone et al., 2002). For the synthesis of compounds (III) and (IV), a mixture of the appropriate 1,2-naphthoquinone (see scheme) (0.02 mol), the Wittig precursor [Me2CH═ CHCH2PPh3]+Br− (0.04 mol), CHCl3 (15 ml) and aqueous NaOH (15 ml of a solution 50% by mass) was vigorously stirred for 48 h at ambient temperature. The organic phase was then separated, washed with water (3 × 10 ml) and dried over magnesium sulfate, and the solvent was removed under reduced pressure. The crude products, (III) and (IV), were purified by chromatography on silica using hexane–dichloromethane (1:1 v/v) as eluent. Crystals suitable for single-crystal X-ray diffraction were grown by slow evaporation of solutions in ethanol.
For compounds (III) and (IV), the space groups Pbca and P21/c, respectively, were uniquely assigned from the systematic absences. All H atoms were located in difference maps and then treated as riding atoms in geometrically idealized positions, with C—H distances 0.95 Å (aromatic and alkenic), 0.98 Å (CH3), 0.99 Å (CH2) and 1.00 Å (aliphatic CH), and with Uiso(H) = kUeq(C), where k = 1.5 for the methyl groups and 1.2 for all other H atoms.
For both compounds, data collection: COLLECT (Nonius, 1999); cell refinement: DENZO (Otwinowski & Minor, 1997) and COLLECT; data reduction: DENZO and COLLECT; program(s) used to solve structure: OSCAIL (McArdle, 2003) and SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: OSCAIL and SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 2003); software used to prepare material for publication: SHELXL97 and PRPKAPPA (Ferguson, 1999).
(III) 6-methoxy-3,3-dimethyl-3
H-benzo[
f]chromene
top
Crystal data top
C16H16O2 | F(000) = 1024 |
Mr = 240.29 | Dx = 1.280 Mg m−3 |
Orthorhombic, Pbca | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ac 2ab | Cell parameters from 2848 reflections |
a = 6.3357 (9) Å | θ = 3.6–27.5° |
b = 15.5230 (2) Å | µ = 0.08 mm−1 |
c = 25.3654 (6) Å | T = 120 K |
V = 2494.7 (4) Å3 | Lath, colourless |
Z = 8 | 0.74 × 0.40 × 0.14 mm |
Data collection top
Bruker Nonius KappaCCD area-detector diffractometer | 2848 independent reflections |
Radiation source: Bruker-Nonius FR591 rotating anode | 2033 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.045 |
Detector resolution: 9.091 pixels mm-1 | θmax = 27.5°, θmin = 3.6° |
ϕ and ω scans | h = −7→8 |
Absorption correction: multi-scan (SADABS; Sheldrick, 2003) | k = −20→12 |
Tmin = 0.957, Tmax = 0.989 | l = −32→32 |
18107 measured reflections | |
Refinement top
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)] = 0.040 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.108 | H-atom parameters constrained |
S = 1.05 | w = 1/[σ2(Fo2) + (0.0647P)2] where P = (Fo2 + 2Fc2)/3 |
2848 reflections | (Δ/σ)max = 0.001 |
166 parameters | Δρmax = 0.18 e Å−3 |
0 restraints | Δρmin = −0.22 e Å−3 |
Crystal data top
C16H16O2 | V = 2494.7 (4) Å3 |
Mr = 240.29 | Z = 8 |
Orthorhombic, Pbca | Mo Kα radiation |
a = 6.3357 (9) Å | µ = 0.08 mm−1 |
b = 15.5230 (2) Å | T = 120 K |
c = 25.3654 (6) Å | 0.74 × 0.40 × 0.14 mm |
Data collection top
Bruker Nonius KappaCCD area-detector diffractometer | 2848 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick, 2003) | 2033 reflections with I > 2σ(I) |
Tmin = 0.957, Tmax = 0.989 | Rint = 0.045 |
18107 measured reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.040 | 0 restraints |
wR(F2) = 0.108 | H-atom parameters constrained |
S = 1.05 | Δρmax = 0.18 e Å−3 |
2848 reflections | Δρmin = −0.22 e Å−3 |
166 parameters | |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | |
O1 | 0.70117 (12) | 0.37579 (5) | 0.68605 (3) | 0.0212 (2) | |
C2 | 0.82434 (18) | 0.30916 (8) | 0.65864 (4) | 0.0219 (3) | |
C21 | 0.6699 (2) | 0.25065 (8) | 0.62982 (5) | 0.0286 (3) | |
C22 | 0.9400 (2) | 0.26182 (8) | 0.70243 (5) | 0.0301 (3) | |
C3 | 0.97423 (19) | 0.35210 (8) | 0.62097 (5) | 0.0238 (3) | |
C4 | 0.91824 (18) | 0.42430 (8) | 0.59660 (4) | 0.0221 (3) | |
C4a | 0.71668 (18) | 0.46481 (7) | 0.60879 (4) | 0.0190 (3) | |
C4b | 0.62045 (17) | 0.53175 (7) | 0.57814 (4) | 0.0190 (3) | |
C5 | 0.7091 (2) | 0.56243 (8) | 0.53040 (5) | 0.0233 (3) | |
C6 | 0.6118 (2) | 0.62464 (8) | 0.50125 (5) | 0.0265 (3) | |
C7 | 0.4195 (2) | 0.66049 (8) | 0.51780 (5) | 0.0273 (3) | |
C8 | 0.32983 (19) | 0.63325 (8) | 0.56408 (5) | 0.0236 (3) | |
C8a | 0.42748 (18) | 0.56946 (7) | 0.59527 (4) | 0.0191 (3) | |
C9 | 0.33652 (17) | 0.54048 (7) | 0.64358 (4) | 0.0187 (3) | |
O9 | 0.15338 (12) | 0.58134 (5) | 0.65701 (3) | 0.0245 (2) | |
C91 | 0.05003 (19) | 0.55380 (8) | 0.70402 (5) | 0.0246 (3) | |
C10 | 0.42760 (17) | 0.47598 (7) | 0.67253 (4) | 0.0186 (3) | |
C10a | 0.61566 (17) | 0.43818 (7) | 0.65416 (4) | 0.0180 (3) | |
H21A | 0.5952 | 0.2838 | 0.6027 | 0.043* | |
H21B | 0.5676 | 0.2272 | 0.6550 | 0.043* | |
H21C | 0.7473 | 0.2033 | 0.6131 | 0.043* | |
H22A | 0.8371 | 0.2357 | 0.7264 | 0.045* | |
H22B | 1.0285 | 0.3026 | 0.7220 | 0.045* | |
H22C | 1.0290 | 0.2167 | 0.6871 | 0.045* | |
H3 | 1.1092 | 0.3276 | 0.6146 | 0.029* | |
H4 | 1.0096 | 0.4495 | 0.5712 | 0.027* | |
H5 | 0.8393 | 0.5391 | 0.5184 | 0.028* | |
H6 | 0.6748 | 0.6439 | 0.4694 | 0.032* | |
H7 | 0.3519 | 0.7034 | 0.4971 | 0.033* | |
H8 | 0.2000 | 0.6577 | 0.5753 | 0.028* | |
H91A | 0.1426 | 0.5639 | 0.7343 | 0.037* | |
H91B | 0.0177 | 0.4922 | 0.7015 | 0.037* | |
H91C | −0.0813 | 0.5863 | 0.7085 | 0.037* | |
H10 | 0.3649 | 0.4570 | 0.7045 | 0.022* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
O1 | 0.0235 (5) | 0.0202 (4) | 0.0199 (4) | 0.0052 (4) | 0.0007 (3) | 0.0013 (3) |
C2 | 0.0243 (6) | 0.0183 (6) | 0.0231 (6) | 0.0054 (5) | 0.0007 (5) | −0.0018 (5) |
C21 | 0.0325 (7) | 0.0216 (6) | 0.0317 (7) | −0.0012 (6) | −0.0009 (6) | −0.0020 (6) |
C22 | 0.0328 (7) | 0.0285 (7) | 0.0288 (7) | 0.0099 (6) | −0.0009 (6) | 0.0030 (6) |
C3 | 0.0206 (7) | 0.0256 (7) | 0.0252 (6) | 0.0038 (5) | 0.0005 (5) | −0.0049 (5) |
C4 | 0.0213 (6) | 0.0250 (7) | 0.0201 (6) | −0.0026 (5) | 0.0022 (5) | −0.0015 (5) |
C4a | 0.0203 (6) | 0.0181 (6) | 0.0187 (6) | −0.0018 (5) | 0.0000 (5) | −0.0025 (5) |
C4b | 0.0217 (6) | 0.0176 (6) | 0.0176 (6) | −0.0034 (5) | −0.0004 (5) | −0.0030 (5) |
C5 | 0.0256 (7) | 0.0226 (6) | 0.0217 (6) | −0.0002 (5) | 0.0046 (5) | −0.0023 (5) |
C6 | 0.0347 (8) | 0.0242 (7) | 0.0206 (6) | −0.0019 (6) | 0.0050 (5) | 0.0017 (6) |
C7 | 0.0362 (8) | 0.0228 (7) | 0.0227 (6) | 0.0030 (6) | −0.0005 (6) | 0.0031 (5) |
C8 | 0.0247 (7) | 0.0216 (6) | 0.0245 (6) | 0.0028 (5) | 0.0011 (5) | −0.0007 (5) |
C8a | 0.0213 (6) | 0.0164 (6) | 0.0196 (6) | −0.0022 (5) | −0.0008 (5) | −0.0018 (5) |
C9 | 0.0162 (6) | 0.0185 (6) | 0.0214 (6) | −0.0003 (5) | 0.0003 (5) | −0.0037 (5) |
O9 | 0.0222 (5) | 0.0258 (5) | 0.0254 (5) | 0.0050 (4) | 0.0062 (4) | 0.0033 (4) |
C91 | 0.0220 (7) | 0.0287 (7) | 0.0232 (6) | 0.0014 (5) | 0.0057 (5) | −0.0008 (5) |
C10 | 0.0195 (6) | 0.0194 (6) | 0.0170 (6) | −0.0035 (5) | 0.0009 (5) | −0.0007 (5) |
C10a | 0.0193 (6) | 0.0160 (6) | 0.0188 (6) | −0.0014 (5) | −0.0033 (5) | −0.0011 (5) |
Geometric parameters (Å, º) top
O1—C10a | 1.3732 (13) | C6—C7 | 1.4035 (18) |
O1—C2 | 1.4704 (13) | C7—C8 | 1.3710 (17) |
C2—C3 | 1.5030 (17) | C8—C8a | 1.4104 (16) |
C2—C22 | 1.5201 (16) | C8a—C9 | 1.4269 (16) |
C2—C21 | 1.5223 (17) | C9—C10 | 1.3692 (16) |
C21—H21A | 0.98 | C10—C10a | 1.4075 (15) |
C21—H21B | 0.98 | C10a—C4a | 1.3802 (15) |
C21—H21C | 0.98 | C4b—C8a | 1.4234 (16) |
C22—H22A | 0.98 | C5—H5 | 0.95 |
C22—H22B | 0.98 | C6—H6 | 0.95 |
C22—H22C | 0.98 | C7—H7 | 0.95 |
C3—C4 | 1.3282 (16) | C8—H8 | 0.95 |
C3—H3 | 0.95 | C9—O9 | 1.3655 (13) |
C4—C4a | 1.4566 (16) | O9—C91 | 1.4259 (14) |
C4—H4 | 0.95 | C91—H91A | 0.98 |
C4a—C4b | 1.4339 (16) | C91—H91B | 0.98 |
C4b—C5 | 1.4174 (16) | C91—H91C | 0.98 |
C5—C6 | 1.3637 (17) | C10—H10 | 0.95 |
| | | |
C10a—O1—C2 | 115.28 (8) | C6—C5—C4b | 121.46 (11) |
O1—C2—C3 | 108.90 (9) | C6—C5—H5 | 119.3 |
O1—C2—C22 | 104.51 (9) | C4b—C5—H5 | 119.3 |
C3—C2—C22 | 111.97 (10) | C5—C6—C7 | 120.74 (11) |
O1—C2—C21 | 107.79 (9) | C5—C6—H6 | 119.6 |
C3—C2—C21 | 111.44 (10) | C7—C6—H6 | 119.6 |
C22—C2—C21 | 111.86 (10) | C8—C7—C6 | 119.57 (11) |
C2—C21—H21A | 109.5 | C8—C7—H7 | 120.2 |
C2—C21—H21B | 109.5 | C6—C7—H7 | 120.2 |
H21A—C21—H21B | 109.5 | C7—C8—C8a | 121.00 (11) |
C2—C21—H21C | 109.5 | C7—C8—H8 | 119.5 |
H21A—C21—H21C | 109.5 | C8a—C8—H8 | 119.5 |
H21B—C21—H21C | 109.5 | C8—C8a—C4b | 119.62 (10) |
C2—C22—H22A | 109.5 | C8—C8a—C9 | 121.73 (11) |
C2—C22—H22B | 109.5 | C4b—C8a—C9 | 118.65 (10) |
H22A—C22—H22B | 109.5 | O9—C9—C8a | 114.27 (10) |
C2—C22—H22C | 109.5 | O9—C9—C10 | 124.33 (10) |
H22A—C22—H22C | 109.5 | C10—C9—C8a | 121.40 (11) |
H22B—C22—H22C | 109.5 | C9—O9—C91 | 117.36 (9) |
C4—C3—C2 | 120.09 (11) | O9—C91—H91A | 109.5 |
C4—C3—H3 | 120.0 | O9—C91—H91B | 109.5 |
C2—C3—H3 | 120.0 | H91A—C91—H91B | 109.5 |
C3—C4—C4a | 119.98 (11) | O9—C91—H91C | 109.5 |
C3—C4—H4 | 120.0 | H91A—C91—H91C | 109.5 |
C4a—C4—H4 | 120.0 | H91B—C91—H91C | 109.5 |
C10a—C4a—C4b | 118.16 (10) | C9—C10—C10a | 118.95 (10) |
C10a—C4a—C4 | 117.01 (10) | C9—C10—H10 | 120.5 |
C4b—C4a—C4 | 124.79 (10) | C10a—C10—H10 | 120.5 |
C5—C4b—C8a | 117.59 (11) | O1—C10a—C4a | 121.29 (10) |
C5—C4b—C4a | 122.56 (11) | O1—C10a—C10 | 115.66 (10) |
C8a—C4b—C4a | 119.85 (10) | C4a—C10a—C10 | 122.94 (11) |
| | | |
C10a—O1—C2—C3 | 47.66 (12) | C5—C4b—C8a—C8 | 1.64 (16) |
C10a—O1—C2—C22 | 167.46 (9) | C4a—C4b—C8a—C8 | −177.89 (11) |
C10a—O1—C2—C21 | −73.39 (11) | C5—C4b—C8a—C9 | −179.17 (10) |
O1—C2—C3—C4 | −34.13 (14) | C4a—C4b—C8a—C9 | 1.30 (16) |
C22—C2—C3—C4 | −149.19 (11) | C8—C8a—C9—O9 | −1.73 (16) |
C21—C2—C3—C4 | 84.65 (14) | C4b—C8a—C9—O9 | 179.10 (9) |
C2—C3—C4—C4a | 3.77 (17) | C8—C8a—C9—C10 | 177.22 (11) |
C3—C4—C4a—C10a | 15.43 (17) | C4b—C8a—C9—C10 | −1.95 (17) |
C3—C4—C4a—C4b | −166.73 (11) | C8a—C9—O9—C91 | 178.09 (10) |
C10a—C4a—C4b—C5 | −178.68 (10) | C10—C9—O9—C91 | −0.82 (17) |
C4—C4a—C4b—C5 | 3.50 (18) | O9—C9—C10—C10a | 179.26 (10) |
C10a—C4a—C4b—C8a | 0.82 (16) | C8a—C9—C10—C10a | 0.42 (17) |
C4—C4a—C4b—C8a | −176.99 (10) | C2—O1—C10a—C4a | −32.52 (14) |
C8a—C4b—C5—C6 | −1.23 (17) | C2—O1—C10a—C10 | 151.18 (9) |
C4a—C4b—C5—C6 | 178.28 (11) | C4b—C4a—C10a—O1 | −178.49 (10) |
C4b—C5—C6—C7 | 0.08 (19) | C4—C4a—C10a—O1 | −0.50 (16) |
C5—C6—C7—C8 | 0.68 (19) | C4b—C4a—C10a—C10 | −2.47 (17) |
C6—C7—C8—C8a | −0.23 (19) | C4—C4a—C10a—C10 | 175.52 (10) |
C7—C8—C8a—C4b | −0.95 (18) | C9—C10—C10a—O1 | 178.10 (10) |
C7—C8—C8a—C9 | 179.89 (11) | C9—C10—C10a—C4a | 1.88 (17) |
(IV) rac-3-bromo-2,2,6,6-tetramethyl-3,4-dihydro-2H,6
H-1,5-dioxatriphenylene
top
Crystal data top
C20H21BrO2 | F(000) = 768 |
Mr = 373.28 | Dx = 1.455 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ybc | Cell parameters from 3910 reflections |
a = 10.7350 (2) Å | θ = 2.0–27.5° |
b = 13.7043 (3) Å | µ = 2.42 mm−1 |
c = 12.0692 (2) Å | T = 120 K |
β = 106.343 (1)° | Block, colourless |
V = 1703.83 (6) Å3 | 0.44 × 0.40 × 0.18 mm |
Z = 4 | |
Data collection top
Bruker Nonius KappaCCD area-detector diffractometer | 3910 independent reflections |
Radiation source: Bruker-Nonius FR591 rotating anode | 3289 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.035 |
Detector resolution: 9.091 pixels mm-1 | θmax = 27.5°, θmin = 2.0° |
ϕ and ω scans | h = −13→13 |
Absorption correction: multi-scan (SADABS;(Sheldrick, 2003) | k = −17→17 |
Tmin = 0.378, Tmax = 0.647 | l = −15→15 |
27068 measured reflections | |
Refinement top
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)] = 0.026 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.088 | H-atom parameters constrained |
S = 1.18 | w = 1/[σ2(Fo2) + (0.0463P)2 + 0.5898P] where P = (Fo2 + 2Fc2)/3 |
3910 reflections | (Δ/σ)max = 0.001 |
212 parameters | Δρmax = 0.43 e Å−3 |
0 restraints | Δρmin = −0.49 e Å−3 |
Crystal data top
C20H21BrO2 | V = 1703.83 (6) Å3 |
Mr = 373.28 | Z = 4 |
Monoclinic, P21/c | Mo Kα radiation |
a = 10.7350 (2) Å | µ = 2.42 mm−1 |
b = 13.7043 (3) Å | T = 120 K |
c = 12.0692 (2) Å | 0.44 × 0.40 × 0.18 mm |
β = 106.343 (1)° | |
Data collection top
Bruker Nonius KappaCCD area-detector diffractometer | 3910 independent reflections |
Absorption correction: multi-scan (SADABS;(Sheldrick, 2003) | 3289 reflections with I > 2σ(I) |
Tmin = 0.378, Tmax = 0.647 | Rint = 0.035 |
27068 measured reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.026 | 0 restraints |
wR(F2) = 0.088 | H-atom parameters constrained |
S = 1.18 | Δρmax = 0.43 e Å−3 |
3910 reflections | Δρmin = −0.49 e Å−3 |
212 parameters | |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | |
O1 | 0.64783 (14) | 0.45972 (10) | 0.79319 (12) | 0.0198 (3) | |
C2 | 0.7502 (2) | 0.39238 (15) | 0.78461 (17) | 0.0203 (4) | |
C21 | 0.7205 (2) | 0.29086 (16) | 0.82207 (19) | 0.0265 (5) | |
C22 | 0.8722 (2) | 0.43516 (19) | 0.86688 (19) | 0.0311 (5) | |
C3 | 0.75145 (19) | 0.39838 (15) | 0.65806 (17) | 0.0195 (4) | |
Br3 | 0.89842 (2) | 0.326417 (16) | 0.630931 (18) | 0.02644 (9) | |
C4 | 0.62668 (19) | 0.36142 (15) | 0.57523 (17) | 0.0191 (4) | |
C4a | 0.5129 (2) | 0.40107 (14) | 0.61074 (16) | 0.0167 (4) | |
C4b | 0.3848 (2) | 0.38825 (13) | 0.53866 (16) | 0.0159 (4) | |
O5 | 0.37728 (14) | 0.34380 (10) | 0.43508 (12) | 0.0201 (3) | |
C6 | 0.2593 (2) | 0.28945 (15) | 0.37892 (17) | 0.0190 (4) | |
C61 | 0.2711 (3) | 0.18812 (15) | 0.4329 (2) | 0.0286 (5) | |
C62 | 0.2602 (2) | 0.28442 (17) | 0.25302 (17) | 0.0246 (5) | |
C7 | 0.1421 (2) | 0.34131 (15) | 0.39436 (18) | 0.0207 (4) | |
C8 | 0.1504 (2) | 0.40043 (14) | 0.48396 (17) | 0.0178 (4) | |
C8a | 0.27603 (19) | 0.42038 (13) | 0.56644 (16) | 0.0157 (4) | |
C8b | 0.29330 (19) | 0.47272 (13) | 0.67280 (16) | 0.0157 (4) | |
C9 | 0.1878 (2) | 0.51017 (14) | 0.70886 (17) | 0.0195 (4) | |
C10 | 0.2084 (2) | 0.55897 (15) | 0.81183 (18) | 0.0230 (4) | |
C11 | 0.3345 (2) | 0.57284 (15) | 0.88449 (18) | 0.0231 (4) | |
C12 | 0.4388 (2) | 0.53802 (14) | 0.85254 (17) | 0.0201 (4) | |
C12a | 0.42136 (19) | 0.48714 (13) | 0.74691 (16) | 0.0162 (4) | |
C12b | 0.52830 (19) | 0.44786 (14) | 0.71427 (16) | 0.0167 (4) | |
H21A | 0.6361 | 0.2691 | 0.7729 | 0.040* | |
H21B | 0.7184 | 0.2929 | 0.9027 | 0.040* | |
H21C | 0.7881 | 0.2453 | 0.8147 | 0.040* | |
H22A | 0.8578 | 0.4458 | 0.9426 | 0.047* | |
H22B | 0.8928 | 0.4975 | 0.8362 | 0.047* | |
H22C | 0.9447 | 0.3897 | 0.8748 | 0.047* | |
H3 | 0.7614 | 0.4686 | 0.6396 | 0.023* | |
H4A | 0.6214 | 0.3828 | 0.4957 | 0.023* | |
H4B | 0.6252 | 0.2892 | 0.5764 | 0.023* | |
H61A | 0.2781 | 0.1939 | 0.5153 | 0.043* | |
H61B | 0.3488 | 0.1557 | 0.4233 | 0.043* | |
H61C | 0.1941 | 0.1495 | 0.3948 | 0.043* | |
H62A | 0.3395 | 0.2516 | 0.2478 | 0.037* | |
H62B | 0.2573 | 0.3507 | 0.2218 | 0.037* | |
H62C | 0.1842 | 0.2477 | 0.2084 | 0.037* | |
H7 | 0.0604 | 0.3318 | 0.3391 | 0.025* | |
H8 | 0.0741 | 0.4297 | 0.4941 | 0.021* | |
H9 | 0.1016 | 0.5013 | 0.6611 | 0.023* | |
H10 | 0.1363 | 0.5837 | 0.8342 | 0.028* | |
H11 | 0.3474 | 0.6063 | 0.9557 | 0.028* | |
H12 | 0.5240 | 0.5481 | 0.9018 | 0.024* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
O1 | 0.0149 (7) | 0.0229 (7) | 0.0190 (7) | 0.0007 (6) | 0.0008 (6) | −0.0050 (6) |
C2 | 0.0146 (10) | 0.0242 (10) | 0.0209 (10) | 0.0027 (8) | 0.0031 (8) | −0.0005 (8) |
C21 | 0.0323 (13) | 0.0259 (11) | 0.0225 (11) | 0.0057 (10) | 0.0098 (9) | 0.0049 (9) |
C22 | 0.0205 (12) | 0.0426 (14) | 0.0252 (11) | 0.0014 (10) | −0.0018 (9) | −0.0071 (10) |
C3 | 0.0142 (10) | 0.0220 (10) | 0.0225 (10) | 0.0010 (8) | 0.0057 (8) | 0.0012 (8) |
Br3 | 0.01572 (13) | 0.03517 (15) | 0.02973 (14) | 0.00178 (8) | 0.00852 (9) | −0.00089 (9) |
C4 | 0.0159 (10) | 0.0230 (10) | 0.0186 (9) | 0.0017 (8) | 0.0050 (8) | −0.0014 (8) |
C4a | 0.0165 (10) | 0.0164 (9) | 0.0176 (9) | −0.0001 (7) | 0.0053 (8) | −0.0003 (7) |
C4b | 0.0183 (10) | 0.0144 (9) | 0.0146 (9) | −0.0001 (7) | 0.0040 (7) | −0.0009 (7) |
O5 | 0.0166 (7) | 0.0273 (7) | 0.0165 (7) | −0.0024 (6) | 0.0047 (6) | −0.0076 (5) |
C6 | 0.0189 (10) | 0.0198 (9) | 0.0165 (9) | −0.0024 (8) | 0.0019 (8) | −0.0040 (8) |
C61 | 0.0359 (14) | 0.0231 (11) | 0.0278 (11) | 0.0008 (9) | 0.0105 (10) | −0.0007 (9) |
C62 | 0.0238 (11) | 0.0305 (12) | 0.0187 (10) | −0.0004 (9) | 0.0045 (8) | −0.0050 (8) |
C7 | 0.0162 (10) | 0.0242 (11) | 0.0193 (10) | −0.0012 (8) | 0.0013 (8) | −0.0002 (8) |
C8 | 0.0148 (10) | 0.0190 (9) | 0.0197 (9) | 0.0015 (8) | 0.0047 (8) | 0.0023 (7) |
C8a | 0.0169 (10) | 0.0147 (9) | 0.0147 (9) | −0.0012 (7) | 0.0029 (7) | 0.0006 (7) |
C8b | 0.0188 (10) | 0.0127 (9) | 0.0161 (9) | 0.0014 (7) | 0.0054 (7) | 0.0011 (7) |
C9 | 0.0203 (10) | 0.0173 (9) | 0.0217 (10) | 0.0028 (8) | 0.0071 (8) | 0.0019 (8) |
C10 | 0.0271 (12) | 0.0202 (10) | 0.0239 (10) | 0.0060 (9) | 0.0106 (9) | 0.0006 (8) |
C11 | 0.0329 (12) | 0.0191 (10) | 0.0185 (10) | 0.0035 (9) | 0.0093 (9) | −0.0035 (8) |
C12 | 0.0238 (11) | 0.0177 (9) | 0.0173 (9) | −0.0007 (8) | 0.0034 (8) | −0.0014 (7) |
C12a | 0.0195 (10) | 0.0127 (9) | 0.0162 (9) | 0.0002 (7) | 0.0050 (7) | 0.0005 (7) |
C12b | 0.0160 (10) | 0.0152 (9) | 0.0169 (9) | −0.0017 (7) | 0.0013 (8) | 0.0013 (7) |
Geometric parameters (Å, º) top
O1—C12b | 1.376 (2) | C11—C12 | 1.369 (3) |
O1—C2 | 1.461 (2) | C12—C12a | 1.419 (3) |
C2—C22 | 1.521 (3) | C12a—C12b | 1.420 (3) |
C2—C21 | 1.524 (3) | C12b—C4a | 1.372 (3) |
C2—C3 | 1.533 (3) | C8b—C12a | 1.427 (3) |
C21—H21A | 0.98 | C4b—O5 | 1.372 (2) |
C21—H21B | 0.98 | O5—C6 | 1.461 (2) |
C21—H21C | 0.98 | C6—C7 | 1.501 (3) |
C22—H22A | 0.98 | C6—C62 | 1.524 (3) |
C22—H22B | 0.98 | C6—C61 | 1.524 (3) |
C22—H22C | 0.98 | C61—H61A | 0.98 |
C3—C4 | 1.515 (3) | C61—H61B | 0.98 |
C3—Br3 | 1.965 (2) | C61—H61C | 0.98 |
C3—H3 | 1.00 | C62—H62A | 0.98 |
C4—C4a | 1.505 (3) | C62—H62B | 0.98 |
C4—H4A | 0.99 | C62—H62C | 0.98 |
C4—H4B | 0.99 | C7—H7 | 0.95 |
C7—C8 | 1.334 (3) | C8—C8a | 1.459 (3) |
C4a—C4b | 1.416 (3) | C8—H8 | 0.95 |
C4b—C8a | 1.375 (3) | C9—H9 | 0.95 |
C8a—C8b | 1.436 (3) | C10—H10 | 0.95 |
C8b—C9 | 1.419 (3) | C11—H11 | 0.95 |
C9—C10 | 1.373 (3) | C12—H12 | 0.95 |
C10—C11 | 1.403 (3) | | |
| | | |
C12b—O1—C2 | 116.74 (15) | C62—C6—C61 | 111.21 (17) |
O1—C2—C22 | 103.72 (16) | C6—C61—H61A | 109.5 |
O1—C2—C21 | 109.37 (17) | C6—C61—H61B | 109.5 |
C22—C2—C21 | 111.81 (18) | H61A—C61—H61B | 109.5 |
O1—C2—C3 | 104.73 (15) | C6—C61—H61C | 109.5 |
C22—C2—C3 | 112.47 (18) | H61A—C61—H61C | 109.5 |
C21—C2—C3 | 113.92 (17) | H61B—C61—H61C | 109.5 |
C2—C21—H21A | 109.5 | C6—C62—H62A | 109.5 |
C2—C21—H21B | 109.5 | C6—C62—H62B | 109.5 |
H21A—C21—H21B | 109.5 | H62A—C62—H62B | 109.5 |
C2—C21—H21C | 109.5 | C6—C62—H62C | 109.5 |
H21A—C21—H21C | 109.5 | H62A—C62—H62C | 109.5 |
H21B—C21—H21C | 109.5 | H62B—C62—H62C | 109.5 |
C2—C22—H22A | 109.5 | C8—C7—C6 | 121.41 (19) |
C2—C22—H22B | 109.5 | C8—C7—H7 | 119.3 |
H22A—C22—H22B | 109.5 | C6—C7—H7 | 119.3 |
C2—C22—H22C | 109.5 | C7—C8—C8a | 120.31 (19) |
H22A—C22—H22C | 109.5 | C7—C8—H8 | 119.8 |
H22B—C22—H22C | 109.5 | C8a—C8—H8 | 119.8 |
C4—C3—C2 | 112.66 (17) | C4b—C8a—C8b | 118.23 (17) |
C4—C3—Br3 | 108.94 (13) | C4b—C8a—C8 | 117.33 (17) |
C2—C3—Br3 | 111.82 (14) | C8b—C8a—C8 | 124.43 (18) |
C4—C3—H3 | 107.7 | C9—C8b—C12a | 117.97 (17) |
C2—C3—H3 | 107.7 | C9—C8b—C8a | 122.77 (18) |
Br3—C3—H3 | 107.7 | C12a—C8b—C8a | 119.25 (18) |
C4a—C4—C3 | 109.21 (16) | C10—C9—C8b | 121.0 (2) |
C4a—C4—H4A | 109.8 | C10—C9—H9 | 119.5 |
C3—C4—H4A | 109.8 | C8b—C9—H9 | 119.5 |
C4a—C4—H4B | 109.8 | C9—C10—C11 | 120.8 (2) |
C3—C4—H4B | 109.8 | C9—C10—H10 | 119.6 |
H4A—C4—H4B | 108.3 | C11—C10—H10 | 119.6 |
C12b—C4a—C4b | 117.69 (18) | C12—C11—C10 | 119.90 (19) |
C12b—C4a—C4 | 121.90 (18) | C12—C11—H11 | 120.0 |
C4b—C4a—C4 | 120.38 (17) | C10—C11—H11 | 120.0 |
O5—C4b—C8a | 121.85 (17) | C11—C12—C12a | 120.87 (19) |
O5—C4b—C4a | 114.40 (17) | C11—C12—H12 | 119.6 |
C8a—C4b—C4a | 123.71 (17) | C12a—C12—H12 | 119.6 |
C4b—O5—C6 | 118.05 (15) | C12—C12a—C12b | 121.55 (18) |
O5—C6—C7 | 110.38 (16) | C12—C12a—C8b | 119.43 (18) |
O5—C6—C62 | 103.78 (16) | C12b—C12a—C8b | 119.00 (17) |
C7—C6—C62 | 112.67 (17) | C4a—C12b—O1 | 122.38 (18) |
O5—C6—C61 | 108.01 (17) | C4a—C12b—C12a | 122.00 (18) |
C7—C6—C61 | 110.50 (18) | O1—C12b—C12a | 115.62 (16) |
| | | |
C12b—O1—C2—C22 | 170.25 (16) | C4a—C4b—C8a—C8 | −179.11 (18) |
C12b—O1—C2—C21 | −70.3 (2) | C7—C8—C8a—C4b | 9.5 (3) |
C12b—O1—C2—C3 | 52.1 (2) | C7—C8—C8a—C8b | −171.85 (19) |
O1—C2—C3—C4 | −64.6 (2) | C4b—C8a—C8b—C9 | 179.12 (18) |
C22—C2—C3—C4 | −176.56 (17) | C8—C8a—C8b—C9 | 0.5 (3) |
C21—C2—C3—C4 | 54.9 (2) | C4b—C8a—C8b—C12a | −1.7 (3) |
O1—C2—C3—Br3 | 172.33 (12) | C8—C8a—C8b—C12a | 179.62 (17) |
C22—C2—C3—Br3 | 60.4 (2) | C12a—C8b—C9—C10 | 0.1 (3) |
C21—C2—C3—Br3 | −68.2 (2) | C8a—C8b—C9—C10 | 179.32 (18) |
C2—C3—C4—C4a | 44.1 (2) | C8b—C9—C10—C11 | −0.2 (3) |
Br3—C3—C4—C4a | 168.73 (13) | C9—C10—C11—C12 | 0.4 (3) |
C3—C4—C4a—C12b | −10.5 (3) | C10—C11—C12—C12a | −0.5 (3) |
C3—C4—C4a—C4b | 171.45 (17) | C11—C12—C12a—C12b | −177.96 (19) |
C12b—C4a—C4b—O5 | 177.96 (17) | C11—C12—C12a—C8b | 0.4 (3) |
C4—C4a—C4b—O5 | −3.9 (3) | C9—C8b—C12a—C12 | −0.2 (3) |
C12b—C4a—C4b—C8a | 0.3 (3) | C8a—C8b—C12a—C12 | −179.42 (17) |
C4—C4a—C4b—C8a | 178.45 (18) | C9—C8b—C12a—C12b | 178.19 (17) |
C8a—C4b—O5—C6 | −28.9 (3) | C8a—C8b—C12a—C12b | −1.0 (3) |
C4a—C4b—O5—C6 | 153.46 (17) | C4b—C4a—C12b—O1 | 176.64 (17) |
C4b—O5—C6—C7 | 38.2 (2) | C4—C4a—C12b—O1 | −1.4 (3) |
C4b—O5—C6—C62 | 159.17 (17) | C4b—C4a—C12b—C12a | −3.3 (3) |
C4b—O5—C6—C61 | −82.7 (2) | C4—C4a—C12b—C12a | 178.65 (18) |
O5—C6—C7—C8 | −26.1 (3) | C2—O1—C12b—C4a | −21.8 (3) |
C62—C6—C7—C8 | −141.6 (2) | C2—O1—C12b—C12a | 158.14 (16) |
C61—C6—C7—C8 | 93.3 (2) | C12—C12a—C12b—C4a | −178.02 (18) |
C6—C7—C8—C8a | 3.4 (3) | C8b—C12a—C12b—C4a | 3.6 (3) |
O5—C4b—C8a—C8b | −175.33 (16) | C12—C12a—C12b—O1 | 2.1 (3) |
C4a—C4b—C8a—C8b | 2.1 (3) | C8b—C12a—C12b—O1 | −176.29 (16) |
O5—C4b—C8a—C8 | 3.4 (3) | | |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
C4—H4A···Cgi | 0.99 | 2.95 | 3.765 (2) | 140 |
Symmetry code: (i) −x+1, −y+1, −z+1. |
Experimental details
| (III) | (IV) |
Crystal data |
Chemical formula | C16H16O2 | C20H21BrO2 |
Mr | 240.29 | 373.28 |
Crystal system, space group | Orthorhombic, Pbca | Monoclinic, P21/c |
Temperature (K) | 120 | 120 |
a, b, c (Å) | 6.3357 (9), 15.5230 (2), 25.3654 (6) | 10.7350 (2), 13.7043 (3), 12.0692 (2) |
α, β, γ (°) | 90, 90, 90 | 90, 106.343 (1), 90 |
V (Å3) | 2494.7 (4) | 1703.83 (6) |
Z | 8 | 4 |
Radiation type | Mo Kα | Mo Kα |
µ (mm−1) | 0.08 | 2.42 |
Crystal size (mm) | 0.74 × 0.40 × 0.14 | 0.44 × 0.40 × 0.18 |
|
Data collection |
Diffractometer | Bruker Nonius KappaCCD area-detector diffractometer | Bruker Nonius KappaCCD area-detector diffractometer |
Absorption correction | Multi-scan (SADABS; Sheldrick, 2003) | Multi-scan (SADABS;(Sheldrick, 2003) |
Tmin, Tmax | 0.957, 0.989 | 0.378, 0.647 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 18107, 2848, 2033 | 27068, 3910, 3289 |
Rint | 0.045 | 0.035 |
(sin θ/λ)max (Å−1) | 0.649 | 0.650 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.040, 0.108, 1.05 | 0.026, 0.088, 1.18 |
No. of reflections | 2848 | 3910 |
No. of parameters | 166 | 212 |
H-atom treatment | H-atom parameters constrained | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.18, −0.22 | 0.43, −0.49 |
Selected geometric parameters (Å, º) for (III) topC3—C4 | 1.3282 (16) | C8—C8a | 1.4104 (16) |
C4a—C4b | 1.4339 (16) | C8a—C9 | 1.4269 (16) |
C4b—C5 | 1.4174 (16) | C9—C10 | 1.3692 (16) |
C5—C6 | 1.3637 (17) | C10—C10a | 1.4075 (15) |
C6—C7 | 1.4035 (18) | C10a—C4a | 1.3802 (15) |
C7—C8 | 1.3710 (17) | C4b—C8a | 1.4234 (16) |
| | | |
O9—C9—C8a | 114.27 (10) | O9—C9—C10 | 124.33 (10) |
| | | |
C8a—C9—O9—C91 | 178.09 (10) | C10—C9—O9—C91 | −0.82 (17) |
Selected bond lengths (Å) for (IV) topC7—C8 | 1.334 (3) | C10—C11 | 1.403 (3) |
C4a—C4b | 1.416 (3) | C11—C12 | 1.369 (3) |
C4b—C8a | 1.375 (3) | C12—C12a | 1.419 (3) |
C8a—C8b | 1.436 (3) | C12a—C12b | 1.420 (3) |
C8b—C9 | 1.419 (3) | C12b—C4a | 1.372 (3) |
C9—C10 | 1.373 (3) | C8b—C12a | 1.427 (3) |
Hydrogen-bond geometry (Å, º) for (IV) top
D—H···A | D—H | H···A | D···A | D—H···A |
C4—H4A···Cgi | 0.99 | 2.95 | 3.765 (2) | 140 |
Symmetry code: (i) −x+1, −y+1, −z+1. |
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Chromenes are of considerable interest, both because of their biological activity (Hepworth, 1984) and because of their useful applications in modern optics (Zhang et al., 2001; Ahmed et al., 2003). We have developed a one-pot synthesis of chromenes which involves the reaction of a 1,2-naphthoquinone, (A) (see scheme), with the allylic Wittig precursor [Me2CH═CHCH2PPh3]+Br− in the presence of concentrated aqueous sodium hydroxide solution to give the intermediate, (B), which undergoes spontaneous cyclization to the chromene, (C), in a hetero Diels–Alder reaction. The Wittig reaction is fully regioselective for the 1-position, with no evidence for any reaction at the 2-position. Thus, reaction of 4-methoxy-1,2,naphthoqinone, (I), yields 9-methoxy-2,2-dimethyl-2H-benzo[d]chromene, (III), while racemic 3-bromo-β-lapachone, (II), yields racemic 3-bromo-2,2,6,6-tetramethyl-3,4-dihydro-2H,6H,1,5-dioxatriphenylene, (IV). Here, we report the structures of compounds (III) and (IV) (Figs. 1 and 2), which we compare briefly with that of the precursor, (II) (De Simone et al., 2002).
Compounds (II) and (IV) each contain a stereogenic centre, at atom C3, but since the precursor, (II), is racemic (De Simone et al., 2002), so also is the product, (IV). Compounds (II) and (IV) both crystallize in centrosymmetric space groups. The reference molecule in the structure of (IV) was selected to have an (S) configuration at C3, just as for compound (II). In each of compounds (III) and (IV), the newly-formed ring adopts a screw-boat conformation. In (III), the ring-puckering parameters (Cremer & Pople, 1975) for the atom sequence O1/C2/C3/C4/C4a/C10a are θ = 113.6 (2)° and ϕ = 215.8 (2)°, while in (IV), the parameters for the atom-sequence O5/C4b/C8a/C8/C7/C6 are θ = 63.2 (4)° and ϕ = 328.4 (4). For the ideal screw-boat conformer, the values are θ = 675 [67.5 ?] or 112.5°, and ϕ = (60n + 30)°, where n represents zero or an integer.
The brominated ring in compound (IV) adopts a half-chair conformation, with the Br substituent occupying an equatorial site and with ring-puckering parameters θ = 128.3 (2)° and ϕ = 262.2 (3) for the atom sequence O1/C2/C3/C4/C4a/C12b. The ideal values are θ = 50.8 or 129.2° and ϕ = (60n + 30)°, where n represents zero or an integer. This conformation was also found for the heterocyclic ring in compound (I) (De Simone et al., 2002).
In each of compounds (III) and (IV), the carbocyclic portion of the molecule shows the marked bond fixation typical of naphthalenes (Tables 1 and 2), while the bonds C3—C4 in compound (III) and C7—C8 in compound (IV) are effectively isolated double bonds. The remaining bond distances show no unusual features. The methoxy C atom in compound (III) is almost coplanar with the adjacent carbocyclic ring, as shown by the relevant torsion angles, and the exocyclic O—C—C angles differ by ca 10°.
While there are no hydrogen bonds of any kind in the structure of compound (III), pairs of molecules are weakly linked into centrosymmetric dimeric aggregates by means of a single aromatic π–π stacking interaction. The unsubstituted aryl rings of the molecules at (x, y, z) and (1 − x, 1 − y, 1 − z) are strictly parallel, with an interplanar spacing of 3.463 (2) Å; the ring centroid separation is 3.853 (2) Å, corresponding to a ring offset of 1.739 (2) Å. The molecules of compound (IV) are also weakly linked into centrosymmetric dimers, this time by a C—H···π(arene) hydrogen bond (Table 3), in which atom C4 in the molecule at (x, y, z) acts as hydrogen-bond donor, via its equatorial H atom H4A, to the aryl ring C4a/C4b/C8a/C8b/C12a/C12b in the molecule at (1 − x, 1 − y, 1 − z) (Fig. 3).
By contrast with the dimeric aggregates formed by compounds (III) and (IV), the molecules of compound (II) are linked into chains of edge-fused rings (Fig. 4) by three independent C—H···O hydrogen bonds [C3—H3···O2ii, C9—H9···O2iii and C10—H10···O3iii; symmetry codes: (ii) 1 − x, 1/2 + y, 1/2 − z; (iii) x, 1 + y, z]. This aggregation was not discussed in the original report on this compound, which was concerned with proof of structure and conformation (De Simone et al., 2002).