J 820 instrument

The 1D and 2D NMR spectra were recorded on a Bruker AVANCE III 500 spectrometer (Bruker, Rheinstetten, Germany). The mass spectra were measured on a JEOL JMS-T100LP mass spectrometer with ESI as an ionization source. The FTIR spectra were measured using a JASCO FT/IR-6100 UV spectra (Japan Spectroscopic Corporation, Tokyo, Japan) were taken on a Hitachi U-2001 spectrophotometer (Hitachi High-Tech Corporation, Tokyo, Japan). Optical rotation was measured on a Jasco P-1010 polarimeter, and ECD spectra were taken on a Jasco J-820 instrument. The presence of sodium was measured on a Hitachi Z-2010 atomic absorption spectrophotometer. High-performance liquid chromatography (HPLC) was performed on a Hitachi L-6000 pump equipped with a Shodex SE-101 RI monitor (Showa Denko, Tokyo, Japan) and a Hitachi L-4000 UV detector using Imtakt Cadenza CD-C18 (10 mm × 250 mm), or Nacalai Cosmosil 5C₁₈-ARII (4.6 mm × 250 mm), or YMC Pack ODS-AQ (4.6 mm × 100 mm) column. Nacalai Cosmosil 75C₁₈-PREP reversed phase gel was used for vacuum flash chromatography. All solvents used were reagent grade.