General Procedure for the NMR Spectroscopy Experiments F NMR spectra were recorded with a Bruker Avance III HD 500 MHz spectrometer equipped with a helium-cooled probe. F chemical shifts (d) are reported in ppm using 1,4-difluorobenzene (-120.00 ppm) as an internal standard. 32 scans per spectrum were collected at a scan rate of 1 second/scan. Typically, aryl halide (0.1 mmol), NBu4F•(H2O)3 (62 mg, 0.2 mmol, 2 equiv.) and the internal standard (0.1 mmol) were dissolved in the THF-d8/D2O mixture (10:1, v/v) in a 2 mL glass vial. The homogeneous solution was transferred into another vial containing the Pd(OAc)2 precatalyst (2 mg, 0.01 mmol) and the boronic acid (0.14 mmol, 1.4 equiv.). As the reaction starts at room temperature, to avoid the loss in information between sample preparation and the start of the measurements, the mixture was immediately transferred into an NMR tube and cooled at -78 ºC until it was frozen. After this, the tube was placed into the NMR spectrometer, and the acquisitions were started while the sample slowly returned to 25 ºC and the reaction proceeded.