preparation of 4-trifluoromethylbenzylboronic acid pinacol ester_industrial additives

preparation background and overview of 4-trifluoromethylbenzylboronic acid pinacol ester

4-trifluoromethylbenzylboronic acid pinacol ester is an organic chemical intermediate that can be used in suzuki coupling reactions.

preparation of 4-trifluoromethylbenzylboronic acid pinacol ester

method 1:

place [cu(mecn)_{4formylbenzeneboronic acid}]²⁺ [bf4^– ]₂ (5.0 mol%, 4.0 mg) and xantphos (6.5 mol%, 7.5 mg) were dissolved in 0.5 ml mtbe in a dry vial in a boron trifluoride tetrahydrofuran complex glove box under argon and the reaction was stirred for 5 minute. then, pinacol diborate (1.2 equiv, 60.9 mg), 1f (1.0 equiv, 35.2 mg) and ti (oⁱpr)₄ (1.0 equiv , 59.2 μl) were added in this order. finally, another 0.5 ml of mtbe was added to the mixture. the reaction was heated to 100°c under argon for 20 hours. pass the crude mixture through a celite pad. then, the solvent was removed on a rotary evaporator (30 °c, 350 mbar). 2f was purified by flash chromatography (pentane/etoac = 97/3), during which some decomposition occurred. isolated yield: 92% (52.8 mg, colorless liquid). ¹hnmr (300mhz, cdcl₃)d 7.46-7.50 (m, 2h), 7.26-7.29 (m, 2h), 2.35 (s, 2h), 1.23 ( s, 12h).¹³c{1h} nmr (75mhz, cdcl₃) 143.3,129.3,127.4 (q, j_c-f = 33hz ), 125.3 (q, j_c-f = 4hz), 124.7 (q, j_c-f = 272hz), 83.8, 24.9, 20.3 (wide, low intensity). ¹¹b nmr (96mhz, cdcl₃) δ32.8,

¹⁹f nmr (470mhz, cdcl₃) δ-62.6, hrms (asap): m/z [m+ h] of c14h19brf3o2 ⁺calculated: 287.1425, found: 287.1422.

method 2:

reaction conditions: aryl tricarboxylate (0.1mmol), pinacol borate (1.5 equivalent), pd(oac)₂ (5mol%), pph_{3</sub (10 mol%), base (3 equiv) in 1 ml in ar atmosphere at room temperature using dioxane for 3-6 h. tbaoh¼tetrabutylammonium hydroxide.}