[F:1][C:2]([F:12])([F:11])[O:3][C:4]1[CH:5]=[C:6](Br)[CH:7]=[CH:8][CH:9]=1.[Mg].[B:14](OC)(OC)OC.S(=O)(=O)(O)O.[OH:26][C:27]([C:30]([OH:33])([CH3:32])[CH3:31])([CH3:29])[CH3:28]>C(OCC)C>[CH3:28][C:27]1([CH3:29])[C:30]([CH3:32])([CH3:31])[O:33][B:14]([C:6]2[CH:7]=[CH:8][CH:9]=[C:4]([O:3][C:2]([F:12])([F:11])[F:1])[CH:5]=2)[O:26]1
2.41 g of 3-(trifluoromethoxy)brombenzene are dissolved in 25 ml of diethyl ether and added dropwise to a suspension of 0.28 g of magnesium in 25 ml of diethyl ether such that the solution remains at the boil. After addition is complete, the mixture is stirred under reflux for 2 h. The cooled solution is added dropwise to a solution of 1.16 ml of trimethyl borate in 25 ml of diethyl ether at a temperature of <−50° C. and then stirred at room temperature for 2 h. 5 ml of 40% strength sulfuric acid and 1.21 g of pinacol are successively added to this solution. After 30 minutes, the solvent is removed on a Rotavapor, the residue is neutralized using saturated sodium hydrogencarbonate solution and the mixture is extracted three times with methyl tert-butyl ether. The organic phase is dried over magnesium sulfate and concentrated in vacuo. 4,4,5,5-Tetramethyl-2-(3-trifluoromethoxyphenyl)-[1,3,2]dioxaborolane is obtained, which is reacted further without further purification.
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