Analytical Techniques for Compound Characterization

UV spectra were obtained by using a Double Beam Spectrophotometer UH5300 (Hitachi High-Technologies, Tokyo, Japan). IR spectra were obtained on a Shimadzu Fourier Transform Infrared spectrometer using KBr pellets. NMR spectra were recorded with a Bruker Avance III 600 MHz spectrometer (Bruker, Karlsruhe, Germany). Optical rotations were measured on a Rudolph Autopol IV polarimeter (Hackettstown, NJ, USA). HRESIMS were measured on an Agilent (Santa Clara, CA, USA) 6200 Q-TOF MS system. Circular dichroism (CD) spectra were measured with an Applied Photophysics spectrometer (Chirascan, New Haven, CT, USA). HPLC was performed on an Agilent 1260 liquid chromatography system equipped with Zorbax (Santa Clara, CA, USA) SB-C18 columns (5 μm, 9.4 mm × 150 mm or 21.2 mm × 150 mm). Sephadex LH-20 (GE Healthcare, Chicago, IL, USA), Silica gel (200–300 mesh), and RP-18 gel (20–45 μm, FuJi, Tokyo, Japan) were used for column chromatography (CC). Chiral separation was carried out on a Chiralpak AD-H chiral column (5 μm, 250 × 4.6 mm; Daicel, Osaka, Japan).