*3.1. General Procedures*

Optical rotations were measured with a Jasco Dip-370 polarimeter (JASCO Inc., Easton, MD, USA.) using CHCl3 as solvent. ECD spectra were measured with JASCO J-810 (JASCO Inc., Easton, MD, USA). First, 1D and 2D NMR spectra were recorded in CDCl3 or DMSO-d6 with a Bruker Avance III 400 instrument (Bruker BioSpin Corporation, San Jose, CA, USA) at 400 MHz for 1H NMR and 100 MHz for 13C NMR using residual CHCl3 as the internal standard. Chemical shift values (δ) are given in parts per million (ppm) and the coupling constants are in Hz. Low-resolution and high-resolution MS were recorded on Shimadzu LCMS-DQ8000α (Shimadzu Scientific Instruments, Inc., Columbia, MD, USA) and Agilent G6224A TOF mass spectrometers (Agilent Technologies Co. Ltd., Beijing, China), respectively. HPLC (Waters Corporation, Milford, MA, USA) was carried out on a 10 × 250 mm Phenomenex Luna 5μ C18 (2) column with Waters Delta Prep system consisting of a PDA 996 detector.
