New self-organised benzo[b]thiophene-based materials for GHz applications

Abstract

The solution of 6-bromobenzothiophene (10.00g -0.047mol) 1, 2-(4pentylphenyl)-1,3,2-dioxaborate (10.19g -0.049mol) 2, anhydrous caesium carbonate Cs 2 CO 3 (53.60 g -0.16 mol), acetone (250cm 3 ) and water (100cm 3 ) were added to a flask and stirred under an N 2 atmosphere and heated up to the boiling temperature and kept under this conditions for 10 minutes. Then it was cooled slowly to 35 o C and palladium(II) acetate (0.1%mol) with XPhos (0.05%mol) was added. Next, mixture was stirred under reflux for 2h. When the reaction was finished acetone was evaporated and obtained mixture was filtered under reduced pressure and washed by 100cm 3 of toluene. Crude product was extracted with toluene. Organic layer was washed two times with water, separated, dried over magnesium sulfate MgSO4 and solvent evaporated. Solid product was purified by column chromatography on silica gel using hexane as eluent and crystallized from anhydrous ethanol. Yield: 10,55g (80,16%). 2-iodo-6-(4-pentylphenyl)benzothiophene 4Anhydrous tetrahydrofuran THF (500cm 3 ) and diisopropylamine (19.88 cm 3 -0.14mol) were introduced into a flask and stirred under an N 2 atmosphere. The reaction mixture was cooled to -78 o C in a dry iceacetone bath. Then n-Butyllithium (56cm 3 -2.50mol/dm 3 ) was added dropwise (temperature of reaction mixture increased by 8°C), followed by 6-(4pentylphenyl)benzothiophene (26.40g -0.094mol) dissolved in anhydrous THF (30cm 3 ). After 10 minutes, iodine (35.56g -0.14mol) dissolved in 100cm 3 of anhydrous THF was added dropwise to the reaction mixture (temperature of reaction mixture increased by 7°C). Thirty minutes after the addition was complete, the cooling bath was removed to allow the solution to reach room temperature. Sodium sulfite was added to the mixture for discoloration. Everything was transferred to a separatory funnel. Organic layer separated and solvent evaporated. Crude product was extracted with dichloromethane Organic layer was washed two times with water, separated, dried over magnesium sulfate MgSO4 and solvent evaporated Solid product was crystallized from ethanol.