U 0080d diode array spectrophotometer

All the chemicals, unless specifically indicated otherwise, were bought from Merck KGaA (Darmstadt, Germany). The melting points, optical rotations, UV and IR spectra were recorded on an MP-S3 micromelting point apparatus (Yanagimoto, Kyoto, Japan), a P-2000 digital polarimeter (Jasco, Tokyo, Japan), a U-0080D diode array spectrophotometer (Hitachi, Tokyo, Japan), and a FT-IR Spectrum RX1 spectrophotometer (PerkinElmer, Waltham, MA, USA), respectively. The ESI-MS and HR-ESI-MS spectra were obtained on a Bruker Daltonics APEX II 30e spectrometer (Bruker, Billerica, MA, USA). ¹H-, ¹³C-, and all 2D NMR (COSY, NOESY, HMQC, and HMBC) spectra were recorded on Bruker AV-500 and Avance III-400 NMR spectrometers (Bruker, Billerica, MA, USA) with tetramethylsilane as the internal standard using deuterated solvents purchased from Sigma-Aldrich (St. Louis, MO, USA). Chemical shifts are reported in parts per million (ppm, δ). Column chromatography and thin layer chromatography (TLC) were conducted on silica gels (Kieselgel 60, 70–230 mesh and 230–400 mesh) and precoated Kieselgel 60 F 254 plates (Merck KGaA), and the compounds were detected by UV light or 10% (v/v) H₂SO₄/EtOH reagent.

The melting point was measured using Yanaco MP-S3 micromelting point apparatus (Yanaco, Tokyo, Japan). Optical rotations were recorded on a Jasco P-2000 digital polarimeter (Jasco, Tokyo, Japan). The UV spectra were obtained by a Hitachi U-0080D diode array spectrophotometer (Hitachi, Tokyo, Japan). The IR spectra were examined with a PerkinElmer FT-IR Spectrum RX1 spectrophotometer (PerkinElmer, Waltham, MA, USA). NMR spectrum was acquired on a Bruker AMX500 (500 MHz) NMR (Bruker, Billerica, MA, USA) and a Jeol JNM-ECA600 (600 MHz) instrument (Jeol, Tokyo, Japan) at a constant temperature controlled and adjusted to room temperature, and chemical shifts are shown in δ values (ppm) with tetramethylsilane as an internal standard. ¹H, ¹³C NMR and 2D spectra were recorded using methanol-d₄ as the solvent. The ECD spectrums were analyzed on the Jasco J-815 spectropolarimeter (Jasco, Tokyo, Japan) with a 5 mm optical pathlength cell. The blank solvent spectra were measured with methanol. The scan ranged from 200–400 nm and was performed at room temperature. The data pitch is 1 nm with scan speed at 100 nm/min and accumulation of the data are the average from 5 scans. The ESI-MS and HR-ESI-MS were taken on a Bruker Solarix FT-MS spectrometer (Bruker, Billerica, MA, USA).

The spectroscopic data of the purified compounds including optical rotations ( ${[\mathsf{\alpha }]}_{\mathrm{D}}^{25}$ ), UV, and IR spectra were recorded on a Jasco P-2000 digital polarimeter (Jasco, Tokyo, Japan), a Hitachi U-0080D diode array spectrophotometer (Hitachi, Tokyo, Japan), and a Jasco FT/IR-4100 spectrophotometer (Jasco, Tokyo, Japan), respectively. The mass spectra were collected on a Shimadzu LC-MS 8040 spectrometer (Shimadzu, Kyoto, Japan). The HRMS data were obtained on a JMS-T100LP spectrometer (Jeol, Tokyo, Japan). ¹H-, ¹³C-, and 2D NMR spectra were recorded on the Bruker AV-500 and Avance III-400 NMR spectrometers (Bruker, Billerica, MA, USA). The deuterated solvents were purchased from Sigma-Aldrich (St. Louis, MO, USA). Other chemicals used in this study were provided by Merck KGaA (Darmstadt, Germany). Column chromatography was performed on silica gels in different mesh sizes (70–230 and 230–400 mesh, Kieselgel 60, Merck KGaA, Darmstadt, Germany). Thin-layer chromatography (TLC) was conducted on precoated Kieselgel 60 F 254 plates (Merck KGaA, Darmstadt, Germany). The spots on TLC were detected by UV light or spraying with 10% (v/v) H₂SO₄ followed by heating at 110 °C for 10 min.