It tof hr mass spectrometer

The optical rotations were determined using a JASCO P-2000 polarimeter (Jasco Co., Tokyo, Japan). The IR spectra were recorded on a Mattson Genesis II spectrometer (Thermo Nicolet, Madison, WI, USA). ESIMS data were obtained on an LCQ mass spectrometer (Thermo Finnigan Co., CA, USA). HREIMS data were measured using a Shimadzu IT-TOF HR mass spectrometer. NMR spectra were recorded on Bruker UltraShield 400 MHz, Varian Inova 500 MHz, and Varian VNMRS 600 MHz spectrometers. For column chromatography (CC), silica gel 60 (70–230 and 230–400 mesh, Merck, Darmstadt, Germany) and Sephadex LH-20 (GE Healthcare, Uppsala, Sweden) were used. Precoated silica gel (Merck 60 F-254) plates were used for TLC. The plates were sprayed with an anisaldehyde−H₂SO₄ (5%) solution and heated at 110 °C to detect the TLC spots. MPLC was performed on a system equipped with a Buchi pump B-688, Buchi B-684 fraction collector, and Buchi columns. HPLC separations were performed on a Shimadzu LC-8A pump with an SPD-20A UV detector, equipped with a 250 × 20 mm i.d. preparative Cosmosil 5C₁₈ AR-II column (Nacalai Tesque, Inc.), and the UV detection wavelength was 210 nm. The single-crystal X-ray diffraction measurements were carried out on a Bruker D8 Venture Dual X-ray single-crystal diffractometer.