General Experimental Procedure
NMR spectra were recorded on a Varian VNMRS spectrometer in CDCl3 at 600 MHz for 1H NMR and 150 MHz
for 13C NMR spectra. Column chromatography was performed with silica gel 60 (70-230 mesh). Thin layer
chromatography was performed with plastic backed plates coated with silica gel F254 and the plates were visualized
by spraying with vanillin/H2SO4 solution followed by warming.