6520 accurate mass q tof lc ms spectrometer

All reactions were carried out in oven-dried glassware under a positive pressure of argon unless otherwise noted. Neomycin B and Kanamycin A free bases were prepared from the corresponding monosulfate salts (purchased from Santa Cruz Biotechnology, inc. and Sigma-Aldrich, respectively) by use of Amberlite-IRA 400 (OH⁻) strongly basic ion-exchange resin. Solvents were dried in a Pure Solv system model PS-400-3-MD. Reactions were monitored by analytical thin-layer chromatography (TLC) on EM silica gel 60 F254 plates (0.25 mm), visualized by ultraviolet light and/or by staining with ceric ammonium molybdate, H₂SO₄ or ninhydrin. Column chromatography was performed on Silice 60 (230–400 µM) and on Amberlite CG-50 (NH4⁺) cation exchange resin. ¹H NMR spectra were recorded on a Varian Inova-400 (400 MHz) and Varian UNITY 500 (500 MHz) in CDCl₃, CD₃OD and D₂O solutions at ambient temperature. Data were reported as follows: chemical shift on the δ scale (either using TMS or residual proton solvent as internal standard), multiplicity (br = broad, s = singlet, d = doublet, t = triplet, q = quartet, m = multiplet), coupling constant(s) in hertz, and integration. ¹³C NMR spectra were recorded on a Varian Inova-400 (100 MHz) and Varian UNITY 500 (125 MHz). Mass spectra were recorded on an AGILENT 6520 Accurate-Mass QTOF LC/MS spectrometer using the electrospray modes (ES).

Compound purification was performed by column chromatography with Merck Silica Gel (40–63 µm) or by flash chromatography (Biotage Isolera One equipment) and the adequate eluyent for each case. Reaction course was monitored by thin layer cromatography (t.l.c.), revealing with UV light (λ = 254 nm) and ethanolic solution of vanillin or ninhydrin. Melting points were determined using a Reichert Thermo Galen Kofler block and are uncorrected. Samples were dissolved in CDCl₃ or DMSO-d₆ using TMS as internal standard for ¹H NMR spectra. In ¹³C NMR spectra, CDCl₃ central signal (77.0 ppm) and DMSO-d (39.5 ppm) were used as references. ¹H-NMR and ¹³C-NMR spectra were obtained in Bruker Avance 300 (300 MHz) and Bruker Avance 400 III HD (400 Hz) spectrometers. Chemical shifts (δ) are given in ppm. Coupling constants (J) are given in Hz. Signal multiplicity is abbreviated as: singlet (s), doublet (d), triplet (t), quartet (c), doublet of doublets (dd), triplet of doublets (td), or multiplet (m). IR spectra were recorded on a Perkin-Elmer Spectrum One B spectrometer. Units are cm⁻¹. Low resolution mass spectra were recorded on an Agilent HP 1,100 LC/MS Spectrometer, whereas High Resolution mass spectrometry (Exact Mass) was performed in an AGILENT 6,520 Accurate-Mass QTOF LC/MS Spectrometer. Elemental analyses were performed in an Elementary Chemical Analyzer LECO CHNS-932.

Optical rotations were measured with a PE model 343 polarimeter. CD spectra were recorded on a JASCO-815 CD spectrometer. A Nicolet 5700 FT-IR microscope instrument was used to record IR spectra. NMR spectra were obtained on INOVA-500 spectrometer. ESIMS were measured with an Agilent 1100 Series LC/MSD Trap mass spectrometer. HRESIMS data were measured using an Agilent 6520 Accurate-Mass Q-TOF LC/MS spectrometer. X-ray experiments were carried on a Gemini E X-ray single crystal diffractometer. A preparative Shimadazu LC-6AD HPLC equipped with SPD-20A and RID-10A detectors (Kyoto, Japan) along with an YMC ODS-A column (250 × 20 mm, 5 μm, Kyoto, Japan) were used to purify the compounds. Macroporous resin (D101 type, The Chemical Plant of NanKai University, China), MCI gel, Mitsubishi chemical corporation, Sepherdex LH-20, GE chemical corporation, Si gel (160–200, 200–300 mesh, Qingdao Marine Chemical Factory, China) and ODS (50 μm, Merck, Germany) were used for column chromatography (CC). TLC was carried out with precoated Si gel plates (Qingdao Marine Chemical Factory, China). Spots were visualized by spraying with 10% EtOH-sulfuric reagent; see supplementary information S4.

Compound purification was performed by column chromatography with Merck Silica Gel (40–63 µm) or by flash chromatography and the adequate eluent for each case. Reaction course was monitored by thin layer chromatography (t.l.c.), revealing with UV light (λ = 254 nm) and ethanolic solution of vanillin or ninhydrin. Melting points were determined using a Reichert Thermo Galen Kofler block and were uncorrected. Samples were dissolved in CDCl₃ or DMSO-d₆ using TMS as internal standard for ¹H NMR spectra. In ¹³C NMR spectra, CDCl₃ central signal (77.0 ppm) and DMSO-d (39.5 ppm) were used as references. ¹H-NMR and ¹³C-NMR spectra were obtained in Bruker Avance 300 (300 MHz) and Bruker Avance 400 III HD (400 Hz) spectrometers. Chemical shifts (δ) are given in ppm. Coupling constants (J) are given in Hz. Signal multiplicity is abbreviated as singlet (s), doublet (d), triplet (t), quartet (c), doublet of doublets (dd), triplet of doublets (td), or multiplet (m). IR spectra were recorded on a Perkin-Elmer Spectrum One B spectrometer. Units are cm⁻¹. Low resolution mass spectra were recorded on an Agilent HP 1100 LC/MS Spectrometer, whereas High Resolution mass spectrometry (Exact Mass) was performed in an AGILENT 6520 Accurate-Mass QTOF LC/MS Spectrometer. Elemental analysis was performed in an Elementary Chemical Analyzer LECO CHNS-932.