Maxis 4g q tof mass spectrometer

Optical rotations were measured on a Perkin-Elmer model 343 polarimeter. UV spectra were recorded on a Hitachi U2910 UV spectrophotometer. ECD measurements were performed on a JASCO J-810 spectropolarimeter. IR spectra were recorded on a Nicolet 6700 FT-IR spectrometer. ¹H and ¹³C, DEPT, HSQC, HMBC, NOESY, and COSY NMR spectra were recorded on a Bruker Avance DRX-400, DRX-700, or a DRX-800 MHz NMR spectrometer. ESIMS, HRESIMS, and MS² spectra were measured on a Bruker Maxis 4G Q-TOF mass spectrometer. All mass spectrometric data were obtained in the positive-ion mode using an ESI ion source, with scan ranges (m/z) from 100 to 1000. For MS² measurements, a dilute sample (around 1 µM in MeOH) was introduced via a syringe pump at a flow rate of 3 µL/min. Column chromatography was conducted using silica gel (65 × 250 or 230 × 400 mesh, Sorbent Technologies). Analytical thin-layer chromatography (TLC) was performed on precoated silica gel 60 F254 plates (Sorbent Technologies). Sephadex LH-20 was purchased from Amersham Biosciences. For visualization of TLC plates, sulfuric acid reagent was used. Fluorescence was tested using a Spectroline (model ENF-260C) UV light source at 386 nm wavelength. All procedures were carried at room temperature using solvents purchased from commercial sources and employed without further purification.

Commercially available starting materials, reagents, and solvents were used as received. Unless otherwise indicated, all reactions were conducted in oven-dried glassware. In general, anhydrous reactions were performed under nitrogen. Reactions were monitored by thin-layer chromatography (TLC) carried out on pre-coated glass plates of silica gel (0.25 mm) 60 F₂₅₄ from EMD Chemicals Inc. Visualization was accomplished with ultraviolet light (UV 254 nm), or by shaking the TLC plate in a sealed jar containing silica gel and iodine. Flash column chromatography was performed using 230–400 mesh silica gel purchased from Silicycle. All work-up and purification procedures were carried out with reagent grade solvents in the air. Yields refer to isolate yield unless otherwise stated. Melting points were determined on a MEL-TEMP 3.0 apparatus. ¹H NMR and ¹³C NMR spectra were recorded on Varian 400 MHz instrument. Chemical shifts are reported in parts per million (ppm) and are calibrated using residual undeuterated solvent as an internal reference (CDCl₃: δ 7.26 ppm; CD₃OD: δ 3.31 ppm; DMSO: δ 2.50 ppm). Data are reported as follows: chemical shift, multiplicity, coupling constants (Hz), and integration. High resolution positive ion mass (HRMS) analyses were conducted on a Bruker MaXis 4G Q-TOF mass spectrometer with electrospray ionization source.

Optical rotations were measured on a Perkin–Elmer 241 Polarimeter. UV spectra were recorded on an Aminco/OLIS UV-Vis Spectrophotometer. ECD spectra were recorded on an AVIV Model 420 Circular Dichroism Spectrometer. IR spectra were measured with a Bruker Equinox 55/S FT–IR Spectrophotometer. Both 1D and 2D NMR spectra were obtained using a Bruker Avance 600 MHz spectrometer with ¹H{¹³C/¹⁵N} cryoprobe and a 500 MHz spectrometer with ¹³C/¹⁵N{¹H} cryoprobe; chemical shifts were referenced to the residual solvent peaks (CD₃OD: δ_H = 3.31, δ_C = 49.15). HRMS and MS/MS data were acquired with a Bruker MaXis 4G QTOF mass spectrometer. RP HPLC was performed using a Shimadzu Prominence HPLC system and a Phenomenex Luna C₁₈ column (250 × 10 mm, 5 µm).