Compound 1
2-(5-(3,5-bis(trifluoromethyl)phenyl)-2-methylthiophen-3-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane
From: Light-driven molecular trap enables bidirectional manipulation of dynamic covalent systems
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Compound data: 1H NMR
Compound data: 13C NMR
Compound data: 19F NMR
Synthetic procedure: See article for the definitive version of this procedure and for full experimental details.
Under an argon atmosphere, 5-(3,5-bis(trifluoromethyl)phenyl)-3-bromo-2-methylthiophene (5.00 g, 12.9 mmol, 1.0 eq.), triethylamine (10.7 mL, 77.1 mmol, 6.0 eq.), and bis(triphenylphosphine)palladium(II) dichloride (0.92 g, 1.2 mmol, 10 mol%) were dissolved in 125 mL of dry and degassed toluene. Then, pinacolborane (5.6 mL, 38.5 mmol, 3.0 eq.) was added and the reaction mixture was refluxed at 120 °C for 16 hours. After cooling to room temperature, the crude mixture was filtered over a pad of Celite and purified by flash column chromatography (SiO2; cyclohexane/ethyl acetate 50:1 with 1 vol% triethylamine) to provide the product (4.5 g, 80%) as a colorless solid. 1H NMR (500 MHz, CDCl3, 25 °C): δ = 7.96 (s, 2H), 7.70 (s, 1H), 7.56 (s, 1H), 2.73 (s, 3H), 1.36 (s, 12H) ppm. 13C{1H} NMR (126 MHz, CDCl3, 25 °C): δ = 154.77 (s), 137.43 (s), 136.65 (s), 132.27 (q, 2J(C,F) = 33.3 Hz), 131.35 (s), 125.71–125.11 (m), 123.42 (q, 1J(C,F) = 272.8 Hz), 120.15 (p, 3J(C,F) = 3.9 Hz)*, 83.76 (s), 25.05 (s), 16.18 (s) ppm. *Full assignment of heptet splitting is not possible due to low intensity. One carbon signal is missing. 19F NMR (471 MHz, CD2Cl2, 25 °C): δ = –63.26 (s, 6F) ppm. MS (API+): m/z calculated for C19H19BF6O2S [M]+: 436.110, found: 436.112.
