All reagents and starting materials were purchased from commercial vendors and used as supplied unless otherwise indicated. All experiments were conducted under air unless otherwise noted. Compounds were purified by column chromatography using silica gel (SiliCycle ® , 60 Å, 230-400 mesh) as stationary phase and solvents mixtures used during chromatography were reported as volume ratios unless otherwise noted. Deuterated solvents were purchased from Cambridge Isotope Laboratories, Inc. and used as received. H NMR, C NMR and 2D NMR spectra were recorded on a 500, 600 or 800 MHz NMR spectrometer, with carrier frequencies of 500.13, 600.13 or 799.75 MHz for 1 H nuclei, and on 600 or 800 MHz NMR spectrometers with carrier frequencies of 150.9 and 201.1 MHz for C nuclei. Chemical shifts are quoted in ppm and were calibrated using the residual solvent peak as the reference. ESI mass spectra were obtained on a Waters Quattro II ESI mass spectrometer. Melting points were measured on an Electrothermal Thermo Scientific IA9100X1 digital melting point instrument.