Chemicals and solvents were purchased from commercial suppliers and purified using standard techniques. For thinlayer chromatography (TLC), silica gel plates Merck 60 F254 were used, and compounds were visualized by irradiation with UV light and/or by treatment with a solution of phosphomolybdic acid (AMC) or vanillin followed by heating. Column chromatography was performed using silica gel Fluka (40-63 µm) or SiliCycle-SiliaFlash P60 (particle size: 40-63 μm, pore diameter: 60 Å. 1 H, 13