Av 300 spectrometer

All the reagents and solvents were obtained from commercial sources and used without further purification. The compounds were characterized by standard spectroscopic techniques. All air-sensitive manipulations were carried out under dry N₂ by Schlenk techniques unless otherwise stated. Solvents were degassed and/or distilled and stored over 3 Å molecular sieves prior to use. Glasswares were oven-dried and placed under vacuum for 30 min prior to use. The progress of reactions was monitored by thin-layer chromatography (TLC) on silica gel 60 F₂₅₄ aluminium-backed plates (Merck). The chromatograms were visualized under ultraviolet radiation (UV) or I₂. Flash column chromatography was conducted using silica gel 60 (Merck). Nuclear magnetic resonance (NMR) spectra were obtained using a Bruker AV 300 spectrometer (¹H at 300 MHz, ¹³C at 75 MHz, ¹⁹F{¹H} at 282 MHz, ³¹P{¹H} at 121 MHz), Bruker AV 400 spectrometer (¹H at 400 MHz, ¹³C at 100 MHz, ³¹P{¹H} at 161 MHz) or Bruker AV 500 spectrometer (¹H at 500 MHz, ¹³C at 125 MHz, ³¹P{¹H} at 202 MHz). ¹H spectra were referenced to an internal SiMe₄ standard at δ 0 or CDCl₃ at δ 7.26. All ¹³C spectra were referenced to CDCl₃ at δ 77.16.