Inova 400 instrument

All reactions were performed in glassware under a positive pressure of argon. Flash column chromatography was performed on a Teledyne ISCO CombiFlash Rf 200 system (Isco, Inc., Lincoln, NE, USA) using silica gel 60 (230–400 mesh). Thin layer chromatography (TLC) analyses were performed on EMD 250 μm Silica Gel 60 F254 plates (Merck KGaA, Darmstadt, Germany) and visualized by quenching of UV fluorescence (λ_max = 254 nm) or by staining with ceric ammonium molybdate. ¹H-NMR spectra were recorded on a Varian Inova-400 instrument (Varian, Inc., Palo Alto, CA, USA). Chemical shifts are reported in ppm (δ) relative to the residual solvent signals of the solvent (δ 7.26 for CHCl₃), coupling constants (J) are reported in Hz and the multiplicities are presented as follows: s = singlet, brs = broad singlet, d = doublet, t = triplet, q = quartet, and m = multiplet. Mass spectra were acquired on Agilent 6120 Single Quadrupole Liquid Chromatography tandem Mass Spectrometer (LC/MS) (Agilent Technologies, Santa Clara, CA, USA). High-resolution mass spectrum was acquired by the Mass Spectrometry Facility at the University of Austin.

Thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC) were used to monitor the chemical separation. TLC was performed using silica gel (60, F254) on 20 × 20 cm aluminum sheets (Merck KGaA, Darmstadt, Germany). The HPLC analysis procedure was carried out as described elsewhere [39 (link)] on a Waters apparatus equipped with Empower Pro software (Waters Corporation, USA). Mass spectrometry analysis was performed on a triple quadrupole mass spectrometer (Waters) using an electrospray Z-spray ion source in ESI positive mode. Source and desolvation temperatures were 150 and 400 °C, respectively. A cone voltage of 20 V and a capillary voltage of 2.5 kV were used. Nitrogen was employed as both a desolvation gas and cone gas. An MS scan was performed using argon gas as the collision gas (Agilent INC, Santa Clara, CA, USA). Compounds 2 and 4 NMR spectra were recorded on an Agilent DD2-600 at 600 MHz and compounds 1 and 3 in a Varian INOVA-400 instrument at 400 MHz for ¹H NMR, NOESY, ¹H-¹H COSY, HSQC, and HMBC and DEPT in CDCl₃ and CD₃OD. Tetramethylsilane was used as an internal reference.

Fluorine-19 (376 MHz) and ¹H (400 MHz) NMR spectra were recorded using a Varian INOVA 400 instrument using a 1 s relaxation time, 60° pulse angle, and 90/10 (v/v) PhCN/C₆D₆ or CDCl₃ as the solvent with a trace amount of C₆F₆ (δ(¹⁹F) –164.90) added as the internal standard. Samples for spectra of 1 or 2 recorded at 23(1) °C were prepared without the exclusion of air; samples for spectra recorded at elevated temperatures and/or with added PS, CoCp₂, or Sn₂(n-Bu)₆ were prepared anaerobically. The program MestReNova 8.1.1 was used to simulate the ¹⁹F NMR spectra of 1 and 2. The uncertainties in the fitted J(FF) values are probably ±1 Hz. Mass spectra were recorded using a 2000 Finnigan LCQ-DUO mass-spectrometer with CH₃CN used as the carrier solvent. UV-vis spectra of samples dissolved in toluene were recorded using a Cary 500 UV-vis-NIR spectrometer.