Agilent 6210 tof lc ms spectrometer

The reagents and alkoxy amine intermediates used in chemical synthesis were purchased directly from the company, such as Macklin, Aladdin, Energy chemical, etc. All solvents were of chemical purity and without further processing, such as petroleum ether (PE), ethyl acetate (EA), dimethylformamide (DMF), dichloromethane (DCM), tetrahydrofuran (THF). Usually, the reactions were monitored by thin-layer chromatography (TLC, Qingdao Marine Chemical Inc., Qingdao, China). The structure of the compounds was confirmed with ¹H NMR, ¹³C NMR spectra, and high-resolution mass spectra (HRMS, Agilent 6210 TOF LC-MS spectrometer, Agilent, Santa Clara, CA, USA). ¹H NMR and ¹³C NMR spectra were collected with JNM-ECZ500R (500 MHz, Jeol, Tokyo, Japan) with CDCl₃ or DMSO-d₆ as solvents and tetramethylsilane (TMS) as internal standard; chemical shift values (δ) were listed in parts per million (ppm). The spectra were analyzed with MestReNova 14.0.

Nuclear magnetic resonance (NMR) spectra were recorded on a Bruker Avance III 400 and 600 MHz NMR spectrometer (Bruker, Rheinstetten, Germany) in CDCl₃ and acetone-d₆ with TMS as an internal standard at room temperature. Ultraviolet (UV) spectra were recorded on a Hitachi U-3000 spectrophotometer (Hitachi, Tokyo, Japan). Optical rotations were measured in MeOH solution on a Rudolph Autopol III automatic polarimeter (Rudolph Research Analytical, NJ, USA). High-resolution-electrospray ionization-mass spectrometry (HR-ESI-MS) spectra were obtained on an Agilent 6210 TOF LC-MS spectrometer (Agilent, CA, USA). X-ray data were obtained on a Bruker APEX-II CCD diffractometer (Bruker, MA, USA). Column chromatography was performed on silica gel (200−300 mesh, Qingdao Marine Chemical Inc., Qingdao, China) and Sephadex LH-20 (Pharmacia Biotech, Uppsala, Sweden). High-performance liquid chromatography (HPLC) was performed on a Shimadzu LC-20AT instrument with an SPD-20A detector (Agilent, CA, USA) using an ODS column (ODS-2 HYPERSIL, 250 × 10 mm, 5 μm, Thermo Scientific, Shanghai, China). All chemicals used in this study were of analytical or HPLC grade.

NMR data were recorded in CDCl₃ using a Bruker DRX-600 spectrometer (600 MHz for ¹H-NMR and 150 MHz for ¹³C-NMR) with TMS (tetramethylsilane) as the internal standard (δ in ppm, J in Hz) (Bruker Corporation, Karlsruhe, Germany). High resolution electrospray ionization mass spectra were obtained on an Agilent 6210 TOF LC-MS spectrometer (Agilent Technologies Inc., Palo Alto, CA, USA). Silica gel (200–300 mesh, Qingdao Marine Chemical Factory, Qingdao, China) and Sephadex LH-20 (GE Healthcare Bio-Sciences AB, Uppsala, Sweden) were used for column chromatography. Semipreparative reverse-phase (RP) HPLC was conducted on an Hitachi HPLC system (Hitachi High-Technologies Corporation, Tokyo, Japan) consisting of a Hitachi L-7110 pump (Hitachi) and a Hitachi L-7420 UV–vis detector equipped with a Hypersil RP-C18 column (5 µm, 250 × 10.0 mm, Thermo Fisher Scientific, Waltham, MA, USA).