Column chromatography was carried out using the Teledyne ISCO CombiFlash ® Rf+ apparatus with RediSep ® silica cartridges (normal-phase), Biotage® SNAP KP-C18 cartridges (reverse-phase) or an EZ Prep® column (preparatory HPLC). Eluent conditions are stated in a form describing a gradient of the minor solvent (e.g. EtOAc) in the major solvent (e.g. cyclohexane).