Mcp 300 polarimeter

The melting points were recorded on a SGW X-4B micro melting point apparatus (Shanghai Precision Scientific Instrument Co., Ltd, Shanghai, China) and were uncorrected. Optical rotations were determined using an MCP 300 polarimeter (Anton Paar, Graz, Austria) at 25 °C. UV data were recorded on a TU-1900 spectrophotometer (Persee, Beijing, China) in MeOH solution. ECD spectra were recorded using a Chirascan CD spectrometer (Applied Photophysics, London, UK). IR spectra were recorded on a Nicolet Nexus 670 spectrophotometer (Thermo Nicolet Corporation, Madison, WI, USA) in KBr discs. All NMR experiments were measured with Bruker Avance 500 spectrometers (500 and 125 MHz) (Bruker BioSpin, Switzerland), and the residual solvent peaks of CDCl₃ (δ_C 77.1/δ_H 7.26), acetone-d₆ (δ_C 29.8 and 206.3/δ_H 2.05), or methanol-d₄ (δ_C 49.0/δ_H 3.31) were used as references. HRESIMS data were acquired on a Thermo Fisher LTQ Orbitrap Elite high-resolution mass spectrometer (Thermo Fisher Scientific, Waltham, MA, USA). Column chromatography (CC) was carried by silica gel (200–300 mesh, Qingdao Maine Chemical Factory) and Sephadex LH-20 (GE Healthcare Bio-Sciences AB, Stockholm, Sweden). Semipreparative HPLC was performed on a Primaide HPLC system (Hitachi Instrument Dalian Co., Ltd, Dalian, China) with an Ultimate XB-C18 column (10 × 250 mm, 10 μm).

Optical rotations were measured at 20 °C in methanol using an Anton Paar MCP 300 polarimeter (Anton Paar, Graz, Austria) in a 100 mm long 350 μL cell. UV spectra for pure molecules were recorded at 20 °C in methanol using a PerkinElmer Lambda 5 spectrophotometer. NMR spectra were recorded on Bruker 500 MHz and 700 MHz spectrometers (Bruker, Rheinstetten, Germany). The chemical shifts (δ) are reported as ppm based on the solvent signal, and coupling constants (J) are in hertz. All solvents were HPLC grade, purchased from Sigma-Aldrich (Saint-Quentin-Fallavier, France).

Optical rotations were measured at 20 °C in methanol using an Anton Paar MCP 300 polarimeter in a 100 mm long 350 μL cell (Anton Paar, Graz, Austria) . UV spectra were recorded at 20 °C in MeOH using a PerkinElmer Lambda 5 spectrophotometer (Thermo Fisher scientific, Les Ulis, France). NMR spectra were recorded on Bruker 700 MHz spectrometers (Bruker, Rheinstetten, Germany). The chemical shifts (δ) are reported as ppm based on the solvent signal, and the coupling constants (J) are given in hertz. Preparative HPLC was conducted with a Gilson system equipped with a 322 pumping device, a GX-271 fraction collector, a 171 diode array detector, and a prep ELSII. All solvents were HPLC grade and purchased from Sigma–Aldrich (Saint-Quentin-Fallavier, France).