6230 lc tofms mass spectrometer

Melting points were measured with the aid of an automated melting point system (SRS OptiMelt MPA100). An Agilent 6230 LC TOFMS mass spectrometer equipped with an Agilent Dual AJS ESI source was used for HR-MS analysis. pH-Values were determined with a WTW pH 340i pocket meter. Molecular weights (M_n) of HA before and after acidic degradation were determined by gel permeation chromatography using a Viscotek GPCmax VE 2001 with a VE 3580 RI detector calibrated with Shodex P-82 pullulan standards.

Commercially available reagents were used without further purification. Reactions were monitored by thin layer chromatography with silica gel 60 F₂₅₄ plates (E. Merck, Darmstadt, Germany). HPLC chromatography was carried out with the Autopurification system by Waters using fluoro-phenyl columns. ¹H and ¹³C NMR spectra were recorded on Bruker AC 200 (¹H: 200 MHz, ¹³C: 50 MHz), Bruker Avance Ultrashield 400 (¹H: 400 MHz, ¹³C: 101 MHz) or Bruker Avance IIIHD 600 spectrometer equipped with a Prodigy BBO cryo probe (¹H: 600 MHz, ¹³C: 151 MHz). Chemical shifts are reported in parts per million (ppm) and were calibrated using DMSO-d₆ as internal standard. Multiplicities are denoted by s (singlet), br s (broad singlet), d (doublet), dd (doublet of doublet) and m (multiplet). Melting points were determined with a Büchi Melting Point B-545 apparatus. HR-MS was measured on an Aglient 6230 LC TOFMS mass spectrometer equipped with an Aglient Dual AJS ESI-Source.
Compounds 1 (PZ II 028), 2 (LAU156), 3 (LAU206) and 4 (LAU176) were synthesized and published previously^{23 (link)}. Synthesis of 5 (DCBS76) was conducted in analogy to previously outlined synthetic routes^{23 (link), 44 (link), 45 (link)}. The synthesis of 6 (DCBS96) was improved as described. Compound 7 (LAU462) was synthesized according to reported protocols^{23 (link), 46 (link), 47 (link)}.