Maxis 2 uhr esi qtof ms instrument

Optical rotation was measured at room temperature with a Perkin-Elmer 241 automatic polarimeter. TLC analysis was performed on Kieselgel 60 F254 (Merck) silica gel plates with visualization by immersing in a sulfuric acid solution (5% in EtOH), followed by heating. Column chromatography was performed on silica gel 60 (Merck 0.063–0.200 mm). Organic solution was dried over MgSO₄ and concentrated under reduced pressure. 1D ¹H, J-modulated ¹³C, 2D ¹H-¹H COSY, ¹H-¹³C HSQC, ¹H-¹³C HSQC-CLIP-COSY (Clean In-Phase Correlation Spectroscopy) [47 (link)], ¹H-¹³C HMBC NMR spectra were recorded with Bruker Avance Neo 700 MHz and Bruker Avance II 500 MHz spectrometers (Bruker, Billerica, MA, USA). Chemical shifts are referenced to Me₄Si or DSS (0.00 ppm for ¹H) and to solvent signals (DMSO: 49.51 ppm for ¹³C). The 1D and 2D NMR spectra of the synthesized compounds can be found in the Supplementary Materials (Figures S1–S5). ESI-QTOF MS measurement was carried out on a maXis II UHR ESI-QTOF MS instrument (Bruker, Billerica, MA, USA) in positive ionization mode.

TLC was performed on Kieselgel 60 F254 (Merck, Darmstadt, Germany) with detection either by immersing into ammonium molybdate-sulfuric acid solution followed by heating for detection. Flash column chromatography was performed using Silica gel 60 (Merck, Darmstadt, Germany, 0.040–0.063 mm). The ¹H-NMR (400 MHz) and ¹³C-NMR (100 MHz) spectra were recorded with a Bruker DRX-400 spectrometer. Chemical shifts are referenced to Me₄Si (0.00 ppm for ¹H) and to the solvent residual signals. ESI-QTOF MS measurement was carried out on a maXis II UHR ESI-QTOF MS instrument (Bruker, Billerica, MA, USA), in positive ionization mode. Constant background correction was applied for the spectrum; the background was recorded before the sample by injecting the blank sample matrix (solvent). Na-formate calibrant was injected after the sample, which enabled internal calibration during data evaluation.