600 or 500 hz nmr spectrometer

For optical rotation the JASCO P-2300 polarimeter (JASCO, Tokyo, Japan) was used; for IR spectra, the Shimazu FTIR-8400S instrument (Shimazu, Columbia, MD 21046, USA) was used. A Bruker 600 or 500 Hz NMR spectrometer was used to record 1D and 2D NMR spectra (Bruker, MA, USA). A JEOL JMS-700 equipment was used to obtain HR-MS spectra (Tokyo, Japan). TLC analysis was conducted with precoated silica gel plates (Merck, Kieselgel60 F₂₅₄, 0.25 mm, Merck, Darmstadt, Germany); chromatography (CC) was conducted with silica gel 60 (Merck, 230–400 mesh, Merck, Darmstadt, Germany). HPLC was carried out with a Jasco PU-980 pump, a Jasco UV-970 intelligent UV detector at 210 nm, and a semi-preparative reversed-phase column (Cosmosil C₁₈, column 250 × 10 mm, 5 μm, Nacalai Tesque, Kyoto, Japan).

A JASCO P-2300 polarimeter was used to measureoptical rotation (Jasco Corporation, Tokyo, Japan). A Shimazi FTIR-8400S was used to measure IR spectra (Columbia, MD 21046, USA). A Bruker 600 or 500 Hz NMR spectrometer was used to record 1D and 2D NMR spectra (MA, USA). Chemical shifts were expressed in parts per million (ppm), while coupling constants were expressed in hertz (Hz). On a JEOL JMS-700 instrument, HR-MS spectra were collected (Tokyo, Japan). A JASCO 810 polarimeter was used to measure electronic circular dichroism (ECD). For column chromatography, Merck’s Silica Gel 60 (230–400 mesh, Merck, Darmstadt, Germany) was employed. TLC examination was performed on precoated silica gel plates (Merck, Kieselgel 60 F254, 0.25 mm, Merck, Darmstadt, Germany). A Jasco PU-980 pump clever HPLC pump was used to perform high-performance liquid chromatography (HPLC).