4-trifluoroMethyl-trans-beta-styrylboronic acid pinacol ester

705-31-7

25015-63-8

1242770-50-8

SIPrCuCl (C8) (4.9 mg, 5 mol%, 0.01 mmol), tris(tert-butyl)phosphinimine (1b) (2.2 mg, 5 mol%, 0.01 mmol), pinacolborane (1c) (28 mg, 0.22 mmol, 1.1 equiv), 4-ethynyl-α,α,α-trifluorotoluene (1) (0.2 mmol, 1 equiv), and benzene (0.2 mg, 0.1 equiv) were added to oven-dried, screw-capped vials in a nitrogen-ambient glove box with an oxygen and moisture content ≤0.1 ppm. 0.22 mmol, 1.1 equiv), 4-ethynyl-α,α,α-trifluorotoluene (1) (0.2 mmol, 1 equiv), and benzene (2 mL, 0.1 M). The formed reaction mixture was stirred in a glove box for 13 to 15 hours. Subsequently, the dark brown reaction mixture was removed from the glove box and the solvent was removed by rotary evaporator. To the reaction residue, mixed solvent (hexane:ethyl acetate) was added as eluent and stirred at room temperature for about 30 minutes until precipitation was formed. The mixture was further filtered through a short silica gel pad to obtain a colorless filtrate. After removal of the organic solvent under reduced pressure, the target product (E)-4,4,5,5-tetramethyl-2-(4-(trifluoromethyl)styryl)-1,3,2-dioxaborolane was obtained by vacuum drying and did not require further purification.