Autopol 1 automatic polarimeter

Optical rotations were carried out on a Rudolph Autopol I automatic polarimeter (Rudolph Research Analytical, Hackettstown, NJ, USA). The UV spectra were measured at a Shimadzu UV-2450 spectrophotometer (Shimadzu Corporation, Kyoto, Japan). IR spectra were determined on a Bruker Tensor 37 infrared spectrophotometer (Bruker Optics, Ettlingen, Germany) with KBr disk. ECD spectra were measured on an Applied Photophysics Chirascan spectrometer (Applied Photophysics Ltd., England). NMR spectra were measured on Bruker AM-400 spectrometer with tetramethylsilane (TMS) as the internal standard. HR-ESIMS data were determined using a Waters Micromass Q-TOF spectrometer (Waters Corporation, Milford, MA, USA). The semi-preparative HPLC was performed on an Essentia LC-16 (Shimadzu, Suzhou, China). Column chromatography (CC) was used using silica gel (200–300 mesh, Qingdao Marine Chemical Factory, Qingdao, China).

The NMR spectra were recorded using Bruker AV500/300MHz spectrometer (Bruker, Fallanden, Switzerland). High-resolution electrospray ionisation mass spectra (HR-ESI-MS) were obtained using a Bruker microTOF QII mass spectrometer (Bruker Daltonics, Fremont, CA, USA). Sephadex LH-20 was purchased from GE Healthcare (USA). Optical rotation was measured using a Rudolph Autopol I automatic polarimeter (Rudolph Research Analytical, Hackettstown, NJ, USA). Silica gel (200–300 mesh) was purchased from Qingdao Haiyang Chemical Co., Ltd, Qingdao, P. R. China. TLC was performed using precoated Silica gel 60 RP-18 F254s glass and aluminum plates (200×200 mm, Merck, Germany). ODS (50 μm) was obtained from YMC(Japan). All other chemicals and solvents were analytical grade.

Non-aqueous reactions were performed under a nitrogen or argon atmosphere and all reaction vessels were oven-dried. Solvents were distilled prior to use: dichloromethane (DCM), triethylamine and diisopropylethylamine (DIPEA) from CaH₂, tetrahydrofuran (THF) from Na/benzophenone. TLCs were carried out using pre-coated sheets (Qingdao silica gel 60-F₂₅₀, 0.2 mm, Qingdao, China) and visualized at 254 nm, and stained in ninhydrin or phosphomolybdic acid solution followed by heating. Flash column chromatography was performed on E. Qingdao silica gel 60 (230–400 mesh ASTM) using the indicated solvents. Optical rotations were measured on AUTOPOL I automatic polarimeter (Rudolph Research Analytical, Hackettstown NJ 07840, USA). NMR spectra were recorded on Bruker spectrometers (Bruker BioSpin AG, Industriestrasse 26, 8117 Fällanden, Switzerland). Chemical shifts were reported in parts per million (ppm), relative to the signals of solvent residue. Data were reported as follows: chemical shift, multiplicity (s = singlet, d = doublet, t = triplet, q = quartet, br = broad), integration and coupling constant. ESI mass spectra were obtained using a AB QSTAR Elite mass spectrometer (International Equipment Trading Ltd. Mundelein, IL 60060, USA).