Palladium-catalysed direct polyheteroarylation of di- or tribromobenzene derivatives: a one step synthesis of conjugated poly(hetero)aromatics

Abstract

The palladium catalysed polyheteroarylation of benzene, biphenyl, fluorene, naphthalene or antracene derivatives via C–H bond functionalisation allows the synthesis of a wide variety of functionalised conjugated poly(hetero)aromatics in only one step. This simple method provides a powerful tool to material chemists allowing to tune easily the physical properties of materials.

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Introduction

Molecular and polymeric semiconducting materials based on conjugated (hetero)aromatic rings have been extensively investigated for twenty years. For example, some arylthiophenes-containing polymers have been used as dye-sensitised solar cells. Such compounds also exhibit fluorescent or photoreversible photochromism properties.¹ They are usually synthesized using Stille, Negishi or Suzuki cross-coupling reactions as the key step.^2–4

One possible approach for an easier and more direct access to polyheteroarylated arenes would obviously be the heteroarylationvia regioselective C–H bond functionalisation of heteroaromatics. In 1990, Ohta et al. reported the coupling of non functional thiophenes, furans or thiazoles with aryl halides, via a C–H bond activation/functionalisation, in moderate to good yields using 5 mol% Pd(PPh₃)₄ as the catalyst.⁵ Since these results, the so-called palladium-catalysed direct arylation of heteroaryl derivatives with aryl halides or triflates has proved to be a powerful method for the synthesis of arylated heterocycles.^6–12 This reaction appears more attractive and useful than palladium catalysed Suzuki, Stille or Negishi cross-couplings, as no previous preparation of an organometallic derivative and its transmetallation product using B(OR)₃, XSnR₃ or ZnX₂ is required (Scheme 1). Actually, one of the major drawbacks of these reactions is the limited substrate scope. To the best of our knowledge, only a few examples of palladium,¹³ruthenium or iridium¹⁴ catalysed direct arylation reactions using dihalobenzenes have been described and they employ quite large amount of catalyst or gave moderate yields. Moreover, to the best of our knowledge, no examples of palladium-catalysed direct coupling using 1,4-dihalonaphthalenes, 9,10-dihaloantracenes or 1,3,5-trihalobenzenes has been reported so far.

Scheme 1

We now report on the catalytic direct regioselective poly heteroarylation of di- or tribromoarenes with a wide variety of heteroaromatics, allowing to tune easily their physical properties.

Results and discussion

First, we attempted to promote the coupling of 2-i-butylthiazole with 1,4-dibromobenzene. For this reaction we employed as little as 0.5 mol% Pd(OAc)₂/dppb [dppb: 1,4-bis(diphenylphosphino)butane] as the catalyst in the presence of KOAc as the base. We had previously observed that these conditions allow to catalyse very efficiently the direct arylation of several heteroaromatics (Scheme 2).¹⁵ We initially employed a 3 : 1 ratio of 2-i-butylthiazole and 1,4-dibromobenzene. In the course of this reaction, after 20 h, almost no coupling product 1 was detected. Only 2 arising from the 1,4-diheteroarylation of 1,4-dibromobenzene was detected, and it was isolated in 76%. As the formation of the monoheteroarylated benzene to give 1 might also be useful, we performed the reaction using a 1 : 4 ratio of 2-i-butylthiazole and 1,4-dibromobenzene. However, the arylation of 1 to produce 2 seems to be much faster than the coupling with 1,4-dibromobenzene to give 1, and the ratio of mono- and diheteroarylated benzene 1:2 was 29 : 71. Even in the presence of a 20 : 1 ratio of the reactants, 1 was formed in only 60% selectivity and 53% yield. However, as 1,4-dibromobenzene is a very cheap reagent, and as its excess can be recycled this procedure might be useful. It should be noted that the use of 4-iodobromobenzene allows to prepare 1 in similar yield of 51% using only a 2 : 1 ratio of thiazole derivative and 4-iodobromobenzene. This is due to the easier oxidative addition of the palladium catalyst into the C–I bond than into the C–Br bond.

Scheme 2

The scope of this reaction was examined with other heteroaromatics using similar reaction conditions and a 3 : 1 ratio of heteroaromatic and 1,4-dibromobenzene (Scheme 3). A furan, a thiophene, a pyrrole and an imidazole substituted at C2 led to the products 3–6 in 71–80% yields. Only the diheteroarylated benzene derivatives were detected. A regioselective arylation at C5 of the heteroaromatics was observed in all cases.

Scheme 3

The synthesis of mixed biheteroarylbenzenes is also possible from 1 (Scheme 4). For example, the reaction of 1 with 2-n-butyrylfuran gives 7 in 79% yield.

Scheme 4

From 1,3-dibromobenzene a similar reactivity than with 1,4- dibromobenzene was observed (Scheme 5). For these couplings, 3 equiv. of 2-substituted furan, thiophene, pyrrole, and also thiazole derivatives have been employed. In all cases, the diheteroarylated products 8–12 were formed in good to high yields. It should be noted that no formation of mono-heteroarylated 1,3-dibromobenzene was detected by GC analysis of the crude mixtures. The use of 2-chlorothiophene led to the C5 arylated thiophene to produce 10 in 66% yield. Under these reaction conditions, the aryl-chloride bond of the thiophene derivative appears to be unreactive.

Scheme 5

Then we attempted the diheteroarylation of 1,4′-dibromobiphenyl, and 2,7-dibromofluorene as such polyheteroarylated aromatics display useful physical properties.¹⁶ Both 1,4′-dibromobiphenyl and 2,7-dibromofluorene were found to give clean reactions, and in the presence of 3 equiv. of 2-i-butylthiazole, the diheteroarylated products 14 and 15 were selectively obtained in 81% and 83% yields (Schemes 6 and 7). It should be noted that in the presence of a 1 : 4 ratio of 2-i-butylthiazole and 1,4′-dibromobiphenyl, the monoheteroarylated biphenyl 13 was obtained in 88% selectivity and 77% yield. The arylation rates of 13 and 1,4′-dibromobiphenyl seems to be relatively similar allowing the formation of 13 in good yield. In the presence of 20 equiv. of 1,4′-dibromobiphenyl, 13 was almost exclusively obtained.

Scheme 6

Scheme 7

1,4′-Dibromobiphenyl was also coupled with 1-(furan-2-yl)butan-1-one, methyl 2-methylfuran-3-carboxylate and 2-acetylthiophene ethylene acetal using again 0.5 mol% Pd(OAc)₂/dppb as the catalyst (Scheme 8). The desired products 16–18 were obtained in good yields of 72–83%.

Scheme 8

The 1,4-diheteroarylation of 1,4-dibromonaphthalene was expected to be more challenging, as this reactant is more hindered (Scheme 9).^17,18 However, we observed that using similar reaction conditions, 0.5 mol% Pd(OAc)₂/dppb as the catalyst at 150 °C, the target compounds 19–26 were obtained in good yields. A wide variety of heteroaromatics bearing useful functional groups have been employed. For example, thiophene 2-carbonitrile and 2-chlorothiophene led to 21 and 22 in 81% and 80% yields, respectively. A pyrrole bearing a formyl substituent at C2 was arylated regioselectively at C5 to produce 24 in 74% yield. In the presence of 2,5-dimethylisoxazole the arylation at C4 was observed to give 26 in 78% yield.

Scheme 9

Anthracenes substituted at C9 and C10 by heteroaromatics are also important building blocks in material chemistry.¹⁹ We have already reported that the direct arylation of some heteroaromatics proceed nicely with 9-bromoanthracene.¹⁷ The coupling of 9,10-dibromoanthracene with ten heteroaromatics was examined, and in all cases, the diheteroarylated anthracene derivatives 27–36 were obtained in 63–86% yields (Scheme 10). The reaction tolerates several functions at C2 or C3 of heteroaromatics such as chloro, acetyl, butyryl, ester or nitrile.

Scheme 10

Finally, we attempted the triheteroarylation of 1,3,5-tribromobenzene (Scheme 11). The synthesis in only one step of such compounds might be important for the preparation of electroluminescent or two-photon absorption materials.^3c,20 It should also allow to prepare building blocks useful for the synthesis of dendrimers. For these couplings we employed 1 mol% PdCl(C₃H₅)(dppb) as the catalyst.^8i,21 We initially examined the reactivity of furan derivatives. In all cases, the desired triheteroarylated benzene derivatives 37–41 were obtained in good yields. Only traces of mono or diheteroarylated benzenes were detected. It should be noted that even furfurylalcohol could be employed.²² The direct use of such heteroaromatics bearing an unprotected hydroxymethyl function is very useful in organic synthesis since it allows to avoid the protection/deprotection sequence. The coupling of several thiophene derivatives with 1,3,5-tribromobenzene also proceed in good yields. Again the coupling was found to be highly regioselective at C5 of all thiophene derivatives. In the presence of 2-chlorothiophene, no cleavage of the C–Cl bond occurs and 43 was obtained in 62% yield. 2-Acetylthiophene was also found to be a suitable coupling partner. The presence of such chloro or acetyl substituents on thiophene should allow the preparation of more complex conjugated structures presenting useful physical properties. The triheteroarylation of 1,3,5-tribromobenzene is not limited to the use of furans or thiophenes. The coupling with 1-methyl-2-formylpyrrole or 2-i-butylthiazole also gives the desired products 46 and 47 in 66% and 80% yields respectively.

Scheme 11 Direct coupling of heteroarenes with 1,3,5-tribromobenzene.

We also performed UV-vis absorption and photoluminescent analysis of some the these compounds (see supplementary material†). UV-vis absorption of compounds 7, 15, 16 and 23 showed quite similar ìmax at ca. 330-360 nm; whereas the absorption maximum, of 36 was shifted about 30 nm at ca. 380 nm. The wavelength of emission was arround 410 nm for product 7, 420 nm for 16, 440 nm for 23, and 450 nm for 36.

Conclusions

In summary, we have demonstrated that polybromobenzenes can be coupled with heteroaromatics, using the simple Pd(OAc)₂ precatalyst in the presence of the profitable influence of a diphosphine ligand (dppb) or using directly PdCl(C₃H₅)(dppb) as the catalyst. When using appropriate reaction conditions, dibromobenzenes, 1,4′-dibromobiphenyl, 2,7-dibromofluorene, 1,4-dibromonaphthalene or 9,10-dibromoanthracene were heteroarylated via C–H bond functionalisation of several heteroaromatics at C5. 1,3,5-Tribromobenzene was also successfully employed to prepare 1,3,5-tri(heteroaryl)benzenes. It should be noted that a wide range of heteroaromatics and functions such as formyl, acetyl, butyryl, ester, nitrile or chloro on the heteroaromatics are tolerated. Such functional group tolerance should allow the easy modification of structures to prepare materials presenting required physical properties. Moreover, this procedure employ a low loading of either a commercially available palladium source associated to a cheap diphosphine ligand, or an easily accessible catalyst.

Experimental

General procedure

As a typical experiment, the reaction of the aryl bromide (1–20 mmol), heteroarene (1–5 mmol) and KOAc (2–5 mmol) at 150 °C during 20 h in DMAc (4–8 mL) in the presence of Pd(OAc)₂/dppb 0.5 mol% or PdCl(C₃H₅)(dppb) 1 mol% (see schemes) under argon affords the coupling product after evaporation of the solvent and purification on silica gel.

Preparation of the PdCl(C₃H₅)(dppb) catalyst:²¹

An oven-dried 40 mL Schlenk tube equipped with a magnetic stirring bar under argon atmosphere, was charged with [Pd(C₃H₅)Cl]₂ (182 mg, 0.5 mmol) and dppb (426 mg, 1 mmol). 10 mL of anhydrous dichloromethane were added, then, the solution was stirred at room temperature for twenty minutes. The solvent was removed in vacuum. The yellow powder was used without purification. ³¹P NMR (81 MHz, CDCl₃) δ = 19.3 (s).

5-(4-Bromophenyl)-2-propylthiazole (1)

From 1,4-dibromobenzene (4.72 g, 20 mmol), 2-i-butylthiazole (0.141 g, 1 mmol) and KOAc (0.196 g, 2 mmol) in DMAc (8 mL) 1 was obtained in 53% (0.157 g) yield. ¹H NMR (300 MHz, CDCl₃): δ 7.73 (s, 1H), 7.42 (d, J = 8.0 Hz, 2H), 7.30 (d, J = 8.0 Hz, 2H), 2.83 (d, J = 7.7 Hz, 2H), 2.14 (m, 1H), 1.08 (d, J = 7.7 Hz, 6H). ¹³C NMR (75 MHz, CDCl₃): δ 170.4, 138.3, 137.5, 132.4, 130.9, 128.3, 122.1, 42.9, 30.1, 22.6. elemental analysis: calcd (%) for C₁₃H₁₄BrNS (296.23): C 52.71, H 4.76; found: C 52.89, H 4.87.

1,4-Di(5-isobutylthiazol-2-yl)benzene (2)

From 1,4-dibromobenzene (0.236 g, 1 mmol), 2-i-butylthiazole (0.423 g, 3 mmol) and KOAc (0.294 g, 3 mmol) in DMAc (4 mL) 2 was obtained in 76% (0.271 g) yield. ¹H NMR (300 MHz, CDCl₃): δ 7.86 (s, 2H), 7.53 (s, 4H), 2.85 (d, J = 7.7 Hz, 4H), 2.14 (m, 2H), 1.08 (d, J = 7.7 Hz, 12H). ¹³C NMR (75 MHz, CDCl₃): δ 169.9, 137.8, 137.7, 131.2, 127.0, 42.6, 29.8, 22.3. elemental analysis: calcd (%) for C₂₀H₂₄N₂S₂ (356.55): C 67.37, H 6.78; found: C 67.24, H 6.95.

1,4-Di(5-butyrylfuran-2-yl)benzene (3)

From 1,4-dibromobenzene (0.236 g, 1 mmol), 1-(furan-2-yl)butan-1-one (0.414 g, 3 mmol) and KOAc (0.294 g, 3 mmol) in DMAc (4 mL) 3 was obtained in 78% (0.273 g) yield. ¹H NMR (300 MHz, CDCl₃): δ 7.86 (s, 4H), 7.28 (d, J = 3.6 Hz, 2H), 6.85 (d, J = 3.6 Hz, 2H), 2.87 (t, J = 7.7 Hz, 4H), 1.82 (sext., J = 7.7 Hz, 4H), 1.04 (t, J = 7.7 Hz, 6H). ¹³C NMR (75 MHz, CDCl₃): δ 189.5, 156.7, 152.3, 130.0, 125.5, 119.3, 108.3, 40.6, 18.2, 14.1. elemental analysis: calcd (%) for C₂₂H₂₂O₄ (350.41): C 75.41, H 6.33; found: C 75.50, H 6.21.

1,4-Di[5-(2-methyl-[1,3]dioxolan-2-yl)-thiophen-2-yl]benzene (4)

From 1,4-dibromobenzene (0.236 g, 1 mmol), 2-acetylthiophene ethylene acetal (0.510 g, 3 mmol) and KOAc (0.294 g, 3 mmol) in DMAc (4 mL) 4 was obtained in 80% (0.331 g) yield. ¹H NMR (300 MHz, CDCl₃): δ 7.58 (s, 4H), 7.19 (d, J = 3.7 Hz, 2H), 7.03 (d, J = 3.7 Hz, 2H), 4.08–3.97 (m, 8H), 1.83 (s, 6H). ¹³C NMR (75 MHz, CDCl₃): δ 147.5, 144.0, 134.1, 126.7, 125.8, 123.4, 107.8, 65.7, 28.2. elemental analysis: calcd (%) for C₂₂H₂₂O₄S₂ (414.54): C 63.74, H 5.35; found: C 63.61, H 5.18.

1,4-Di(1-methyl-2-formylpyrrol-5-yl)benzene (5)

From 1,4-dibromobenzene (0.236 g, 1 mmol), 1-methyl-2-formylpyrrole (0.329 g, 3 mmol) and KOAc (0.294 g, 3 mmol) in DMAc (4 mL) 5 was obtained in 71% (0.207 g) yield. ¹H NMR (300 MHz, CDCl₃): δ 9.56 (s, 2H), 7.50 (s, 4H), 6.97 (d, J = 4.0 Hz, 2H), 6.34 (d, J = 4.0 Hz, 2H), 3.96 (s, 6H). ¹³C NMR (75 MHz, CDCl₃): δ 179.1, 142.6, 132.8, 130.7, 128.8, 123.9, 110.5, 33.9. elemental analysis: calcd (%) for C₁₈H₁₆N₂O₂ (292.33): C 73.95, H 5.52; found: C 73.99, H 5.61.

1,4-Di(1,2-dimethylimidazol-5-yl)benzene (6)

From 1,4-dibromobenzene (0.236 g, 1 mmol), 1,2-dimethylimidazole (0.288 g, 3 mmol) and KOAc (0.294 g, 3 mmol) in DMAc (4 mL) 6 was obtained in 74% (0.197 g) yield. ¹H NMR (300 MHz, CDCl₃): δ 7.29 (s, 4H), 6.86 (s, 2H), 3.58 (s, 6H), 2.47 (s, 6H). ¹³C NMR (75 MHz, CDCl₃): δ 146.5, 133.2, 130.0, 128.9, 126.2, 31.7, 13.9. elemental analysis: calcd (%) for C₁₆H₁₈N₄ (266.34): C 72.15, H 6.81; found: C 72.20, H 6.97.

1-(5-isobutylthiazol-2-yl)-4-(5-butyrylfuran-2-yl)benzene (7)

From 5-(4-bromophenyl)-2-propylthiazole (1) (0.296 g, 1 mmol), 1-(furan-2-yl)butan-1-one (0.276 g, 2 mmol) and KOAc (0.196 g, 2 mmol) in DMAc (4 mL) 7 was obtained in 79% (0.279 g) yield. ¹H NMR (300 MHz, CDCl₃): δ 7.90 (s, 1H), 7.81 (d, J = 8.0 Hz, 2H), 7.60 (d, J = 8.0 Hz, 2H), 7.27 (d, J = 3.8 Hz, 1H), 6.80 (d, J = 3.8 Hz, 1H), 2.90 (d, J = 7.7 Hz, 2H), 2.86 (t, J = 7.7 Hz, 2H), 2.16 (m, 1H), 1.82 (sext., J = 7.7 Hz, 2H), 1.02–1.08 (m, 9H). ¹³C NMR (75 MHz, CDCl₃): δ 188.7, 169.7, 156.1, 151.4, 137.5, 137.1, 131.7, 128.2, 126.3, 124.9, 118.5, 107.1, 42.0, 39.8, 29.2, 21.7, 17.4, 13.3. elemental analysis: calcd (%) for C₂₁H₂₃NO₂S (353.48): C 71.35, H 6.56; found: C 71.24, H 6.65.

1,3-Di(5-butyrylfuran-2-yl)benzene (8)

From 1,3-dibromobenzene (0.236 g, 1 mmol), 1-(furan-2-yl)butan-1-one (0.414 g, 3 mmol) and KOAc (0.294 g, 3 mmol) in DMAc (4 mL) 8 was obtained in 79% (0.276 g) yield. ¹H NMR (300 MHz, CDCl₃): δ 8.15 (s, 1H), 7.79 (d, J = 7.8 Hz, 2H), 7.51 (t, J = 7.8 Hz, 1H), 7.28 (d, J = 3.6 Hz, 2H), 6.88 (d, J = 3.6 Hz, 2H), 2.88 (t, J = 7.7 Hz, 4H), 1.82 (sext., J = 7.7 Hz, 4H), 1.04 (t, J = 7.7 Hz, 6H). ¹³C NMR (75 MHz, CDCl₃): δ 189.3, 156.5, 152.2, 130.2, 129.5, 125.5, 121.1, 119.0, 108.1, 40.4, 18.0, 13.9. elemental analysis: calcd (%) for C₂₂H₂₂O₄ (350.41): C 75.41, H 6.33; found: C 75.32, H 6.21.

1,3 Di(methyl 2-methyl-3-carboxylatefuran-5-yl)benzene (9)

From 1,3-dibromobenzene (0.236 g, 1 mmol), methyl 2-methylfuran-3-carboxylate (0.420 g, 3 mmol) and KOAc (0.294 g, 3 mmol) in DMAc (4 mL) 9 was obtained in 76% (0.269 g) yield. ¹H NMR (300 MHz, CDCl₃): δ 7.91 (s, 1H), 7.55 (d, J = 7.8 Hz, 2H), 7.42 (t, J = 7.8 Hz, 1H), 6.97 (s, 2H), 3.85 (s, 6H), 2.66 (s, 6H). ¹³C NMR (75 MHz, CDCl₃): δ 164.0, 158.6, 151.0, 130.1, 128.8, 122.4, 118.4, 114.8, 105.6, 51.0, 13.5. elemental analysis: calcd (%) for C₂₀H₁₈O₆ (354.35): C 67.79, H 5.12; found: C 67.70, H 5.20.

1,3-Bis(5-chlorothiophen-2-yl)benzene (10)

From 1,3-dibromobenzene (0.236 g, 1 mmol), 2-chlorothiophene (0.355 g, 3 mmol) in DMAc (4 mL) 10 was obtained in 66% (0.205 g) yield. ¹H NMR (300 MHz, CDCl₃): δ 7.62 (s, 1H), 7.46–7.34 (m, 3H), 7.12 (d, J = 3.8 Hz, 2H), 6.93 (d, J = 3.8 Hz, 2H). ¹³C NMR (75 MHz, CDCl₃): δ 142.0, 134.3, 129.5, 129.4, 127.0, 124.8, 122.6, 122.4. elemental analysis: calcd (%) for C₁₄H₈Cl₂S₂ (311.25): C 54.02, H 2.59; found: C 54.09, H 2.70.

1,3-Di(1-methyl-2-formylpyrrol-5-yl)benzene (11)

From 1,3-dibromobenzene (0.236 g, 1 mmol), 1-methyl-2-formylpyrrole (0.329 g, 3 mmol) and KOAc (0.294 g, 3 mmol) in DMAc (4 mL) 11 was obtained in 78% (0.228 g) yield. ¹H NMR (300 MHz, CDCl₃): δ 9.62 (s, 2H), 7.91 (s, 1H), 7.54 (t, J = 7.8 Hz, 1H), 7.51 (d, J = 7.8 Hz, 2H), 7.02 (d, J = 3.8 Hz, 2H), 6.36 (d, J = 3.8 Hz, 2H), 3.93 (s, 6H). ¹³C NMR (75 MHz, CDCl₃): δ 179.7, 143.1, 133.3, 131.7, 129.8, 129.2, 129.0, 124.3, 111.0, 34.4. elemental analysis: calcd (%) for C₁₈H₁₆N₂O₂ (292.33): C 73.95, H 5.52; found: C 73.84, H 5.60.

1,3-Di(5-isobutylthiazol-2-yl)benzene (12)

From 1,3-dibromobenzene (0.236 g, 1 mmol), 2-i-butylthiazole (0.423 g, 3 mmol) and KOAc (0.294 g, 3 mmol) in DMAc (4 mL) 12 was obtained in 83% (0.296 g) yield. ¹H NMR (300 MHz, CDCl₃): δ 7.83 (s, 2H), 7.61 (t, J = 1.6 Hz, 1H), 7.45–7.32 (m, 3H), 2.86 (d, J = 7.7 Hz, 4H), 2.12 (m, 2H), 1.00 (d, J = 7.7 Hz, 12H). ¹³C NMR (75 MHz, CDCl₃): δ 169.5, 137.5, 137.2, 132.0, 129.1, 125.5, 124.2, 42.0, 29.3, 21.7. elemental analysis: calcd (%) for C₂₀H₂₄N₂S₂ (356.55): C 67.37, H 6.78; found: C 67.47, H 6.64.

5-(4′-Bromobiphenyl-4-yl)-2-isobutylthiazole (13)

From 4,4′-dibromobiphenyl (1.248 g, 4 mmol), 2-i-butylthiazole (0.141 g, 1 mmol) and KOAc (0.196 g, 2 mmol) in DMAc (4 mL) 13 was obtained in 77% (0.286 g) yield. ¹H NMR (300 MHz, CDCl₃): δ 7.89 (s, 1H), 7.65–7.55 (m, 6H), 7.48 (d, J = 8.2 Hz, 2H), 2.91 (d, J = 7.7 Hz, 2H), 2.18 (m, 1H), 1.06 (d, J = 7.7 Hz, 6H). ¹³C NMR (75 MHz, CDCl₃): δ 169.9, 139.4, 139.2, 137.9, 137.8, 132.0, 131.1, 128.5, 127.4, 127.0, 121.8, 42.6, 29.8, 22.3. elemental analysis: calcd (%) for C₁₉H₁₈BrNS (372.32): C 61.29, H 4.87; found: C 61.40, H 4.69.

4,4′-Di(5-isobutylthiazol-2-yl)biphenyl (14)

From 4,4′-dibromobiphenyl (0.312 g, 1 mmol), 2-i-butylthiazole (0.423 g, 3 mmol) and KOAc (0.294 g, 3 mmol) in DMAc (4 mL) 14 was obtained in 81% (0.350 g) yield. ¹H NMR (300 MHz, CDCl₃): δ 7.67 (s, 2H), 7.45–7.35 (m, 8H), 2.90 (d, J = 7.7 Hz, 4H), 2.18 (m, 2H), 1.06 (d, J = 7.7 Hz, 12H). ¹³C NMR (75 MHz, CDCl₃): δ 169.7, 139.6, 137.9, 137.6, 130.8, 127.2, 126.8, 42.4, 29.7, 22.2. elemental analysis: calcd (%) for C₂₆H₂₈N₂S₂ (432.65): C 72.18, H 6.52; found: C 72.29, H 6.41.

2,7-Di(5-isobutylthiazol-2-yl)fluorene (15)

From 2,7-dibromofluorene (0.324 g, 1 mmol), 2-i-butylthiazole (0.423 g, 3 mmol) and KOAc (0.294 g, 3 mmol) in DMAc (4 mL) 15 was obtained in 83% (0.369 g) yield. ¹H NMR (500 MHz, CDCl₃): δ 7.90 (s, 2H), 7.78 (d, J = 8.0 Hz, 2H), 7.73 (s, 2H), 7.59 (d, J = 8.0 Hz, 2H), 3.98 (s, 2H), 2.92 (d, J = 7.2 Hz, 4H), 2.18 (m, 2H), 1.06 (d, J = 6.7 Hz, 12H). ¹³C NMR (125 MHz, CDCl₃): δ 169.5, 144.2, 141.0, 138.9, 137.5, 130.4, 125.6, 123.2, 120.5, 42.6, 36.8, 29.8, 22.3. elemental analysis: calcd (%) for C₂₇H₂₈N₂S₂ (444.66): C 72.93, H 6.35; found: C 72.81, H 6.56.

4,4′-Di(5-butyrylfuran-2-yl)biphenyl (16)

From 4,4′-dibromobiphenyl (0.312 g, 1 mmol), 1-(furan-2-yl)butan-1-one (0.414 g, 3 mmol) and KOAc (0.294 g, 3 mmol) in DMAc (4 mL) 16 was obtained in 72% (0.307 g) yield. ¹H NMR (300 MHz, CDCl₃): δ 7.90 (d, J = 8.0 Hz, 4H), 7.71 (d, J = 8.0 Hz, 4H), 7.29 (d, J = 3.4 Hz, 2H), 6.84 (d, J = 3.4 Hz, 2H), 2.84 (t, J = 7.7 Hz, 4H), 1.80 (sext., J = 7.7 Hz, 4H), 1.06 (t, J = 7.7 Hz, 6H). ¹³C NMR (75 MHz, CDCl₃): δ 189.2, 157.0, 152.0, 140.6, 128.8, 127.3, 125.4, 119.1, 107.6, 40.4, 18.0, 13.9. elemental analysis: calcd (%) for C₂₈H₂₆O₄ (426.50): C 78.85, H 6.14; found: C 78.91, H 6.03.

4,4-Di(methyl 2-methyl-3-carboxylatefuran-5-yl)biphenyl (17)

From 4,4′-dibromobiphenyl (0.312 g, 1 mmol), methyl 2-methylfuran-3-carboxylate (0.420 g, 3 mmol) and KOAc (0.294 g, 3 mmol) in DMAc (4 mL) 17 was obtained in 75% (0.322 g) yield. ¹H NMR (300 MHz, CDCl₃): δ 7.72 (d, J = 8.0 Hz, 4H), 7.65 (d, J = 8.0 Hz, 4H), 6.94 (s, 2H), 3.88 (s, 6H), 2.69 (s, 6H). ¹³C NMR (75 MHz, CDCl₃): δ 163.8, 158.3, 150.9, 138.9, 128.5, 126.5, 123.5, 114.6, 105.1, 50.8, 13.3. elemental analysis: calcd (%) for C₂₆H₂₂O₆ (430.45): C 72.55, H 5.15; found: C 72.48, H 5.24.

4,4′-Di[5-(2-methyl-[1,3]dioxolan-2-yl)-thiophen-2-yl]biphenyl (18)

From 4,4′-dibromobiphenyl (0.312 g, 1 mmol), 2-acetylthiophene ethylene acetal (0.510 g, 3 mmol) and KOAc (0.294 g, 3 mmol) in DMAc (4 mL) 18 was obtained in 83% (0.407 g) yield. ¹H NMR (300 MHz, CDCl₃): δ 7.70–7.62 (m, 8H), 7.23 (d, J = 3.7 Hz, 2H), 7.07 (d, J = 3.7 Hz, 2H), 4.20–4.00 (m, 8H), 1.86 (s, 6H). ¹³C NMR (75 MHz, CDCl₃): δ 146.6, 143.2, 139.2, 133.3, 127.0, 125.9, 124.9, 122.6, 107.0, 64.8, 27.3. elemental analysis: calcd (%) for C₂₈H₂₆O₄S₂ (490.64): C 68.54, H 5.34; found: C 68.35, H 5.39.

1,4 Di(methyl 2-methyl-3-carboxylatefuran-5-yl)naphthalene (19)

From 1,4-dibromonaphthalene (0.286 g, 1 mmol), methyl 2-methylfuran-3-carboxylate (0.420 g, 3 mmol) and KOAc (0.294 g, 3 mmol) in DMAc (4 mL) 19 was obtained in 82% (0.331 g) yield. ¹H NMR (300 MHz, CDCl₃): δ 8.50–8.40 (m, 2H), 7.78 (s, 2H), 7.65–7.55 (m, 2H), 7.02 (s, 2H), 3.91 (s, 6H), 2.75 (s, 6H). ¹³C NMR (75 MHz, CDCl₃): δ 164.0, 158.9, 150.3, 130.1, 127.5, 126.4, 125.3, 125.0, 114.7, 110.0, 51.0, 13.6. elemental analysis: calcd (%) for C₂₄H₂₀O₆ (404.41): C 71.28, H 4.98; found: C 71.32, H 4.87.

1,4-Di(5-methylthiophen-2-yl)naphthalene (20)

From 1,4-dibromonaphthalene (0.286 g, 1 mmol), 2-methylthiophene (0.294 g, 3 mmol) and KOAc (0.294 g, 3 mmol) in DMAc (4 mL) 20 was obtained in 84% (0.269 g) yield. ¹H NMR (300 MHz, CDCl₃): δ 8.50–8.40 (m, 2H), 7.63–7.52 (m, 4H), 7.12 (d, J = 3.3 Hz 2H), 6.92 (d, J = 3.3 Hz 2H), 2.65 (s, 6H). ¹³C NMR (75 MHz, CDCl₃): δ 139.9, 138.9, 132.4, 131.8, 127.0, 126.9, 125.8, 125.7, 125.1, 14.9. elemental analysis: calcd (%) for C₂₀H₁₆S₂ (320.47): C 74.96, H 5.03; found: C 75.04, H 5.11.

1,4-Di(5-cyanothiophen-2-yl)naphthalene (21)

From 1,4-dibromonaphthalene (0.286 g, 1 mmol), thiophene 2-carbonitrile (0.327 g, 3 mmol) in DMAc (4 mL) 21 was obtained in 81% (0.277 g) yield. ¹H NMR (300 MHz, CDCl₃): δ 8.20–8.15 (m, 2H), 7.75 (d, J = 3.8 Hz 2H), 7.65–7.61 (m, 2H), 7.60 (s, 2H), 7.31 (d, J = 3.8 Hz 2H). ¹³C NMR (75 MHz, CDCl₃): δ 148.1, 137.2, 131.4, 131.2, 127.7, 127.4, 127.3, 125.2, 113.5, 109.7. elemental analysis: calcd (%) for C₂₀H₁₀N₂S₂ (342.44): C 70.15, H 2.94; found: C 70.31, H 3.10.

1,4-Di(5-chlorothiophen-2-yl)naphthalene (22)

From 1,4-dibromonaphthalene (0.286 g, 1 mmol), 2-chlorothiophene (0.355 g, 3 mmol) in DMAc (4 mL) 22 was obtained in 80% (0.289 g) yield. ¹H NMR (300 MHz, CDCl₃): δ 8.25–8.15 (m, 2H), 7.60–7.50 (m, 4H), 7.10–7.04 (m, 4H). ¹³C NMR (75 MHz, CDCl₃): δ 140.4, 132.6, 132.5, 130.6, 128.0, 127.4, 127.3, 126.9, 126.4. elemental analysis: calcd (%) for C₁₈H₁₀Cl₂S₂ (361.31): C 59.84, H 2.79; found: C 59.64, H 2.70.

1,4-Di[5-(2-methyl-[1,3]dioxolan-2-yl)-thiophen-2-yl]naphthalene (23)

From 1,4-dibromonaphthalene (0.286 g, 1 mmol), 2-acetylthiophene ethylene acetal (0.510 g, 3 mmol) and KOAc (0.294 g, 3 mmol) in DMAc (4 mL) 23 was obtained in 85% (0.395 g) yield. ¹H NMR (300 MHz, CDCl₃): δ 8.40–8.32 (m, 2H), 7.59 (s, 2H), 7.58–7.51 (m, 2H), 7.17 (d, J = 3.5 Hz 2H), 7.15 (d, J = 3.5 Hz 2H), 4.12 (s, 8H), 1.92 (s, 6H). ¹³C NMR (75 MHz, CDCl₃): δ 146.8, 140.2, 131.6, 131.1, 126.5, 126.4, 125.5, 125.2, 123.4, 106.2, 64.1, 26.6. elemental analysis: calcd (%) for C₂₆H₂₄O₄S₂ (464.60): C 67.21, H 5.21; found: C 67.35, H 5.35.

1,4-Di(1-methyl-2-formylpyrrol-5-yl)naphthalene (24)

From 1,4-dibromonaphthalene (0.286 g, 1 mmol), 1-methyl-2-formylpyrrole (0.329 g, 3 mmol) and KOAc (0.294 g, 3 mmol) in DMAc (4 mL) 24 was obtained in 74% (0.253 g) yield. ¹H NMR (300 MHz, CDCl₃): δ 9.70 (s, 2H), 7.72–7.65 (m, 2H), 7.60–7.50 (m, 4H), 7.14 (d, J = 4.0 Hz 2H), 6.44 (d, J = 4.0 Hz 2H), 3.76 (s, 6H). ¹³C NMR (75 MHz, CDCl₃): δ 180.2, 142.1, 133.2, 133.0, 130.8, 128.4, 127.8, 126.5, 124.7, 112.7, 34.6. elemental analysis: calcd (%) for C₂₂H₁₈N₂O₂ (342.39): C 77.17, H 5.30; found: C 77.04, H 5.41.

1,4-Di(5-isobutylthiazol-2-yl)naphthalene (25)

From 1,4-dibromonaphthalene (0.286 g, 1 mmol), 2-i-butylthiazole (0.423 g, 3 mmol) and KOAc (0.294 g, 3 mmol) in DMAc (4 mL) 25 was obtained in 86% (0.349 g) yield. ¹H NMR (300 MHz, CDCl₃): δ 8.20–8.10 (m, 2H), 7.74 (s, 2H), 7.55–7.45 (m, 4H), 2.92 (d, J = 7.2 Hz, 4H), 2.20 (m, 2H), 1.04 (d, J = 7.2 Hz, 6H). ¹³C NMR (75 MHz, CDCl₃): δ 170.9, 141.4, 135.0, 132.2, 129.9, 127.9, 126.9, 125.8, 42.4, 29.8, 22.4. elemental analysis: calcd (%) for C₂₄H₂₆N₂S₂ (406.61): C 70.89, H 6.45; found: C 70.99, H 6.58.

1,4-Di(3,5-dimethylisoxazol-4-yl)naphthalene (26)

From 1,4-dibromonaphthalene (0.286 g, 1 mmol), 3,5-dimethylisoxazole (0.291 g, 3 mmol) and KOAc (0.294 g, 3 mmol) in DMAc (4 mL) 26 was obtained in 78% (0.248 g) yield. ¹H NMR (300 MHz, CDCl₃): δ 7.62–7.55 (m, 2H), 7.50–7.42 (m, 2H), 7.31 (s, 2H), 2.24 (s, 6H), 2.07 (s, 6H). ¹³C NMR (75 MHz, CDCl₃): δ 166.0, 159.5, 132.2, 127.9, 127.6, 126.3, 125.5, 114.4, 11.2, 10.3. elemental analysis: calcd (%) for C₂₀H₁₈N₂O₂ (318.37): C 75.45, H 5.70; found: C 75.31, H 5.59.

9,10-Bis(5-butylfuran-2-yl)-anthracene (27)

From 9,10-dibromoanthracene (0.336 g, 1 mmol), 2-n-butylfuran (0.372 g, 3 mmol) and KOAc (0.294 g, 3 mmol) in DMAc (4 mL) 27 was obtained in 76% (0.321 g) yield. ¹H NMR (300 MHz, CDCl₃): δ 8.10–8.02 (m, 4H), 7.52–7.45 (m, 4H), 6.63 (d, J = 3.0 Hz, 2H), 6.36 (d, J = 3.0 Hz, 2H), 2.85 (t, J = 7.7 Hz, 4H), 1.78 (quint., J = 7.7 Hz, 4H), 1.56 (sext., J = 7.7 Hz, 4H), 1.03 (t, J = 7.7 Hz, 6H). ¹³C NMR (75 MHz, CDCl₃): δ 157.6, 148.7, 131.7, 128.3, 127.0, 126.1, 113.5, 106.5, 30.8, 28.4, 22.7, 14.3. elemental analysis: calcd (%) for C₃₀H₃₀O₂ (422.56): C 85.27, H 7.16; found: C 85.11, H 7.37.

9,10-Bis(5-butyrylfuran-2-yl)-anthracene (28)

From 9,10-dibromoanthracene (0.336 g, 1 mmol), 1-(furan-2-yl)butan-1-one (0.414 g, 3 mmol) and KOAc (0.294 g, 3 mmol) in DMAc (4 mL) 28 was obtained in 80% (0.360 g) yield. ¹H NMR (300 MHz, CDCl₃): δ 7.93–7.85 (m, 4H), 7.55–7.47 (m, 4H), 7.46 (d, J = 3.5 Hz, 2H), 6.85 (d, J = 3.5 Hz, 2H), 2.91 (t, J = 7.7 Hz, 4H), 1.83 (sext., J = 7.7 Hz, 4H), 1.03 (t, J = 7.7 Hz, 6H). ¹³C NMR (75 MHz, CDCl₃): δ 190.0, 154.1, 153.5, 131.1, 127.0, 126.8, 126.1, 117.7, 115.3, 40.6, 17.9, 14.0. elemental analysis: calcd (%) for C₃₀H₂₆O₄ (450.53): C 79.98, H 5.82; found: C 80.10, H 6.02.

9,10-Bis(5-acetoxymethylfuran-2-yl)-anthracene (29)

From 9,10-dibromoanthracene (0.336 g, 1 mmol), furfuryl acetate (0.420 g, 3 mmol) and KOAc (0.294 g, 3 mmol) in DMAc (4 mL) 29 was obtained in 77% (0.350 g) yield. ¹H NMR (300 MHz, CDCl₃): δ 8.00–7.92 (m, 4H), 7.53–7.45 (m, 4H), 6.77 (d, J = 2.7 Hz, 2H), 6.71 (d, J = 2.7 Hz, 2H), 5.25 (s, 4H), 2.15 (s, 6H). ¹³C NMR (75 MHz, CDCl₃): δ 171.2, 151.4, 150.6, 131.7, 127.9, 126.8, 126.6, 114.0, 112.3, 58.9, 21.5. elemental analysis: calcd (%) for C₂₈H₂₂O₆ (454.47): C 74.00, H 4.88; found: C 74.14, H 5.01.

9,10 Di(methyl 2-methyl-3-carboxylatefuran-5-yl)anthracene (30)

From 9,10-dibromoanthracene (0.336 g, 1 mmol), methyl 2-methylfuran-3-carboxylate (0.420 g, 3 mmol) and KOAc (0.294 g, 3 mmol) in DMAc (4 mL) 30 was obtained in 79% (0.359 g) yield. ¹H NMR (300 MHz, CDCl₃): δ 7.90–7.80 (m, 4H), 7.40–7.30 (m, 4H), 6.86 (s, 2H), 3.80 (s, 6H), 2.66 (s, 6H). ¹³C NMR (75 MHz, CDCl₃): δ 164.6, 160.0, 148.0, 131.2, 126.9, 126.3, 126.2, 114.7, 113.2, 51.5, 14.1. elemental analysis: calcd (%) for C₂₈H₂₂O₆ (454.47): C 74.00, H 4.88; found: C 74.12, H 5.04.

9,10-Bis(5-methylthiophen-2-yl)anthracene (31)

From 9,10-dibromoanthracene (0.336 g, 1 mmol), 2-methylthiophene (0.294 g, 3 mmol) and KOAc (0.294 g, 3 mmol) in DMAc (4 mL) 31 was obtained in 84% (0.311 g) yield. ¹H NMR (300 MHz, CDCl₃): δ 8.10–8.05 (m, 4H), 7.52–7.45 (m, 4H), 7.07 (d, J = 3.0 Hz, 2H), 7.03 (d, J = 3.0 Hz, 2H), 2.73 (s, 6H). ¹³C NMR (75 MHz, CDCl₃): δ 140.7, 136.0, 130.9, 130.0, 128.9, 126.3, 125.0, 124.8, 14.9. elemental analysis: calcd (%) for C₂₄H₁₈S₂ (370.53): C 77.80, H 4.90; found: C 77.72, H 5.02.

9,10-Bis(5-cyanothiophen-2-yl)anthracene (32)

From 9,10-dibromoanthracene (0.336 g, 1 mmol), thiophene 2-carbonitrile (0.327 g, 3 mmol) in DMAc (4 mL) 32 was obtained in 74% (0.290 g) yield. ¹H NMR (300 MHz, CDCl₃): δ 7.90 (d, J = 3.7 Hz, 2H), 7.85–7.70 (m, 4H), 7.60–7.45 (m, 4H), 7.27 (d, J = 3.7 Hz, 2H). ¹³C NMR (75 MHz, CDCl₃): δ 146.3, 137.5, 130.8, 129.8, 127.8, 126.5, 125.7, 113.6, 111.2. elemental analysis: calcd (%) for C₂₄H₁₂N₂S₂ (392.50): C 73.44, H 3.08; found: C 73.52, H 3.00.

9,10-Bis(5-acetylthiophen-2-yl)anthracene (33)

From 9,10-dibromoanthracene (0.336 g, 1 mmol), 2-acetylthiophene (0.378 g, 3 mmol) in DMAc (4 mL) 33 was obtained in 63% (0.269 g) yield. ¹H NMR (300 MHz, CDCl₃): δ 7.78 (d, J = 3.5 Hz, 2H), 7.70–7.62 (m, 4H), 7.30–7.22 (m, 4H), 7.09 (d, J = 3.5 Hz, 2H), 2.63 (s, 6H). ¹³C NMR (75 MHz, CDCl₃): δ 190.7, 147.8, 145.8, 132.7, 130.9, 130.7, 129.5, 126.3, 126.2, 26.9. elemental analysis: calcd (%) for C₂₆H₁₈O₂S₂ (426.55): C 73.21, H 4.25; found: C 73.04, H 4.31.

9,10-Bis(5-chlorothiophen-2-yl)anthracene (34)

From 9,10-dibromoanthracene (0.336 g, 1 mmol), 2-chlorothiophene (0.355 g, 3 mmol) in DMAc (4 mL) 34 was obtained in 83% (0.341 g) yield. ¹H NMR (300 MHz, CDCl₃): δ 8.10–7.90 (m, 4H), 7.60–7.40 (m, 4H), 7.17 (d, J = 3.3 Hz, 2H), 7.02 (d, J = 3.3 Hz, 2H). ¹³C NMR (75 MHz, CDCl₃): δ 137.5, 131.4, 130.9, 129.5, 129.0, 126.5, 126.4, 126.1. elemental analysis: calcd (%) for C₂₂H₁₂Cl₂S₂ (411.37): C 64.23, H 2.94; found: C 64.31, H 2.84.

9,10-Bis[5-(2-methyl-[1,3]dioxolan-2-yl)thiophen-2-yl]anthracene (35)

From 9,10-dibromoanthracene (0.336 g, 1 mmol), 2-acetylthiophene ethylene acetal (0.510 g, 3 mmol) and KOAc (0.294 g, 3 mmol) in DMAc (4 mL) 35 was obtained in 86% (0.442 g) yield. ¹H NMR (300 MHz, CDCl₃): δ 8.00–7.90 (m, 4H), 7.50–7.40 (m, 4H), 7.28 (d, J = 3.5 Hz, 2H), 7.08 (d, J = 3.5 Hz, 2H), 4.17 (m, 8H), 1.98 (s, 6H). ¹³C NMR (75 MHz, CDCl₃): δ 148.6, 138.6, 131.3, 130.2, 129.3, 126.7, 125.7, 124.3, 107.3, 35.1, 27.5. elemental analysis: calcd (%) for C₃₀H₂₆O₄S₂ (514.66): C 70.01, H 5.09; found: C 70.10, H 5.02.

9,10-Bis(5-isobutylthiazol-2-yl)anthracene (36)

From 9,10-dibromoanthracene (0.336 g, 1 mmol), 2-i-butylthiazole (0.423 g, 3 mmol) and KOAc (0.294 g, 3 mmol) in DMAc (4 mL) 36 was obtained in 78% (0.356 g) yield. ¹H NMR (300 MHz, CDCl₃): δ 7.90–7.80 (m, 4H), 7.74 (s, 2H), 7.45–7.35 (m, 4H), 3.07 (d, J = 7.7 Hz, 4H), 2.29 (m, 2H), 1.12 (d, J = 7.7 Hz, 12H). ¹³C NMR (75 MHz, CDCl₃): δ 171.8, 142.8, 131.6, 131.0, 126.4, 125.9, 125.7, 42.1, 29.5, 22.1. elemental analysis: calcd (%) for C₂₈H₂₈N₂S₂ (456.67): C 73.64, H 6.18; found: C 73.71, H 6.25.

1,3,5-Tris(5-butylfuran-2-yl)-benzene (37)

1,3,5-tribromobenzene (0.315 g, 1 mmol), 2-n-butylfuran (0.620 g, 5 mmol) and KOAc (0.490 g, 5 mmol) in DMAc (4 mL) 37 was obtained in 73% (0.324 g) yield. ¹H NMR (300 MHz, CDCl₃): δ 7.77 (s, 3H), 6.69 (d, J = 3.0 Hz, 3H), 6.12 (d, J = 3.0 Hz, 3H), 2.76 (t, J = 7.7 Hz, 6H), 1.74 (quint., J = 7.7 Hz, 6H), 1.52 (sext., J = 7.7 Hz, 6H), 0.99 (t, J = 7.7 Hz, 9H). ¹³C NMR (75 MHz, CDCl₃): δ 156.7, 151.8, 131.8, 116.7, 106.8, 106.2, 30.2, 27.9, 22.3, 13.8. elemental analysis: calcd (%) for C₃₀H₃₆O₃ (444.61): C 81.04, H 8.16; found: C 81.02, H 8.08.

1,3,5-Tris(5-butyrylfuran-2-yl)-benzene (38)

1,3,5-tribromobenzene (0.315 g, 1 mmol), 1-(furan-2-yl)butan-1-one (0.690 g, 3 mmol) and KOAc (0.490 g, 5 mmol) in DMAc (4 mL) 38 was obtained in 62% (0.301 g) yield. ¹H NMR (300 MHz, CDCl₃): δ 8.10 (s, 3H), 7.29 (d, J = 3.7 Hz, 3H), 6.96 (d, J = 3.7 Hz, 3H), 2.87 (t, J = 7.7 Hz, 6H), 1.83 (sext., J = 7.7 Hz, 6H), 1.03 (t, J = 7.7 Hz, 9H). ¹³C NMR (75 MHz, CDCl₃): δ 189.2, 155.7, 152.3, 130.9, 121.4, 119.0, 108.7, 40.4, 17.9, 13.9. elemental analysis: calcd (%) for C₃₀H₃₀O₆ (486.56): C 74.06, H 6.21; found: C 74.21, H 6.14.

[1,3,5-Tris-(5-acetoxymethylfuran-2-yl)benzene (39)

1,3,5-tribromobenzene (0.315 g, 1 mmol), furfuryl acetate (0.700 g, 5 mmol) and KOAc (0.490 g, 5 mmol) in DMAc (4 mL) 39 was obtained in 74% (0.364 g) yield. ¹H NMR (300 MHz, CDCl₃): δ 7.86 (s, 3H), 6.76 (d, J = 3.4 Hz, 3H), 6.54 (d, J = 3.4 Hz, 3H), 5.15 (s, 6H), 2.12 (s, 9H). ¹³C NMR (75 MHz, CDCl₃): δ 170.5, 153.9, 149.6, 131.5, 118.7, 112.7, 106.8, 58.2, 20.8. elemental analysis: calcd (%) for C₂₇H₂₄O₉ (492.47): C 65.85, H 4.91; found: C 65.99, H 4.97.

1,3,5-Tris-(5-hydroxymethylfuran-2-yl)benzene (40)

1,3,5-tribromobenzene (0.315 g, 1 mmol), furfurylalcohol (0.490 g, 5 mmol) and KOAc (0.490 g, 5 mmol) in DMAc (4 mL) 40 was obtained in 70% (0.256 g) yield. ¹H NMR (300 MHz, MeOD): δ 7.88 (s, 3H), 6.82 (d, J = 3.2 Hz, 3H), 6.42 (d, J = 3.2 Hz, 3H), 4.60 (s, 6H). ¹³C NMR (75 MHz, MeOD): δ 156.1, 154.4, 133.2, 118.5, 110.7, 107.7, 57.6. elemental analysis: calcd (%) for C₂₁H₁₈O₆ (366.36): C 68.85, H 4.95; found: C 68.69, H 5.08.

1,3,5-Tris-(methyl 2-methyl-3-carboxylatefuran-5-yl)benzene (41)

1,3,5-tribromobenzene (0.315 g, 1 mmol), methyl 2-methylfuran-3-carboxylate (0.700 g, 5 mmol) and KOAc (0.490 g, 5 mmol) in DMAc (4 mL) 41 was obtained in 72% (0.354 g) yield. . ¹H NMR (300 MHz, CDCl₃): δ 7.68 (s, 3H), 6.94 (s, 3H), 3.86 (s, 9H), 2.67 (s, 9H). ¹³C NMR (75 MHz, CDCl₃): δ 164.2, 159.1, 150.8, 130.8, 117.5, 115.2, 106.4, 51.4, 13.9. elemental analysis: calcd (%) for C₂₇H₂₄O₉ (492.47): C 65.85, H 4.91; found: C 65.68, H 5.08.

1,3,5-Tris(5-methylthiophen-2-yl)benzene (42)²³

1,3,5-tribromobenzene (0.315 g, 1 mmol), 2-methylthiophene (0.490 g, 5 mmol) and KOAc (0.490 g, 5 mmol) in DMAc (4 mL) 42 was obtained in 78% (0.285 g) yield. ¹H NMR (300 MHz, CDCl₃): δ 7.64 (s, 3H), 7.22 (d, J = 3.0 Hz, 3H), 6.80 (d, J = 3.0 Hz, 3H), 2.62 (s, 9H). ¹³C NMR (75 MHz, CDCl₃): δ 141.1, 139.8, 135.6, 126.1, 123.3, 121.2, 15.3.

1,3,5-Tris(5-chlorothiophen-2-yl)benzene (43)²³

1,3,5-tribromobenzene (0.315 g, 1 mmol), 2-chlorothiophene (0.592 g, 5 mmol) and KOAc (0.490 g, 5 mmol) in DMAc (4 mL) 43 was obtained in 62% (0.265 g) yield. ¹H NMR (300 MHz, CDCl₃): δ 7.49 (s, 3H), 7.14 (d, J = 3.8 Hz, 3H), 6.93 (d, J = 3.8 Hz, 3H). ¹³C NMR (75 MHz, CDCl₃): δ 141.4, 135.2, 130.1, 127.2, 123.2, 121.9.

1,3,5-Tris(5-acetylthiophen-2-yl)benzene (44)²⁴

1,3,5-tribromobenzene (0.315 g, 1 mmol), 2-acetylthiophene (0.630 g, 5 mmol) and KOAc (0.490 g, 5 mmol) in DMAc (4 mL) 44 was obtained in 67% (0.301 g) yield. ¹H NMR (300 MHz, CDCl₃): δ 7.85 (s, 3H), 7.71 (d, J = 3.9 Hz, 3H), 7.43 (d, J = 3.9 Hz, 3H), 2.61 (s, 9H). ¹³C NMR (75 MHz, CDCl₃): δ 190.5, 150.4, 144.2, 135.2, 133.3, 125.0, 124.1, 26.6.

1,3,5-Tris[5-(2-methyl-[1,3]dioxolan-2-yl)-thiophen-2-yl]benzene (45)

1,3,5-tribromobenzene (0.315 g, 1 mmol), 2-acetylthiophene ethylene acetal (0.850 g, 5 mmol) and KOAc (0.490 g, 5 mmol) in DMAc (4 mL) 45 was obtained in 77% (0.448 g) yield. ¹H NMR (300 MHz, CDCl₃): δ 7.68 (s, 3H), 7.25 (d, J = 3.6 Hz, 3H), 7.05 (d, J = 3.6 Hz, 3H), 4.08 (m, 12H), 1.84 (s, 9H). ¹³C NMR (75 MHz, CDCl₃): δ 147.3, 142.7, 135.4, 124.9, 123.3, 121.9, 107.0, 64.9, 27.3. elemental analysis: calcd (%) for C₃₀H₃₀O₆S₃ (582.75): C 61.83, H 5.19; found: C 61.94, H 5.08.

1,3,5-Tris(1-methyl-2-formylpyrrol-5-yl)benzene (46)

1,3,5-tribromobenzene (0.315 g, 1 mmol), 1-methyl-2-formylpyrrole (0.548 g, 3 mmol) and KOAc (0.490 g, 5 mmol) in DMAc (4 mL) 46 was obtained in 66% (0.263 g) yield. ¹H NMR (300 MHz, CDCl₃): δ 9.63 (s, 3H), 7.52 (s, 3H), 7.02 (d, J = 3.6 Hz, 3H), 6.39 (d, J = 3.6 Hz, 3H), 4.01 (s, 9H). ¹³C NMR (75 MHz, CDCl₃): δ 179.8, 142.1, 133.5, 132.3, 129.6, 124.3, 111.3, 34.5. elemental analysis: calcd (%) for C₂₄H₂₁N₃O₃ (399.44): C 72.16, H 5.30; found: C 72.28, H 5.41.

1,3,5-Tris(2-isobutylthiazol-5-yl)benzene (47)

1,3,5-tribromobenzene (0.315 g, 1 mmol), 2-i-butylthiazole (0.705 g, 5 mmol) and KOAc (0.490 g, 5 mmol) in DMAc (4 mL) 47 was obtained in 80% (0.396 g) yield. ¹H NMR (300 MHz, CDCl₃): δ 7.87 (s, 3H), 7.54 (s, 3H), 2.88 (d, J = 7.2 Hz, 6H), 2.18 (m, 3H), 1.01 (d, J = 7.2 Hz, 18H). ¹³C NMR (75 MHz, CDCl₃): δ 170.5, 138.5, 137.0, 133.3, 124.1, 42.6, 29.8, 22.3. elemental analysis: calcd (%) for C₂₇H₃₃N₃S₃ (495.77): C 65.41, H 6.71; found: C 65.40, H 6.90.

1,3,5-Tris(3,5-dimethylisoxazol-4-yl)benzene (48)

1,3,5-tribromobenzene (0.315 g, 1 mmol), 3,5-dimethylisoxazole (0.485 g, 5 mmol) and KOAc (0.490 g, 5 mmol) in DMAc (4 mL) 48 was obtained in 77% (0.280 g) yield. ¹H NMR (300 MHz, CDCl₃): δ 7.13 (s, 3H), 2.48 (s, 9H), 2.34 (s, 9H). ¹³C NMR (75 MHz, CDCl₃): δ 165.6, 158.3, 131.6, 128.6, 115.8, 11.8, 11.0. elemental analysis: calcd (%) for C₂₁H₂₁N₃O₃ (363.41): C 69.41, H 5.82; found: C 69.40, H 6.04.

Acknowledgements

Support provided from the ANR program for Sustainable Chemistry Development (ANR-09-CP2D-03 CAMELOT), Rennes Métropole and CNRS.

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Footnote

† Electronic Supplementary Information (ESI) available. See DOI: 10.1039/c1ra00370d/

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