Synthesis and Characterization of Novel Compounds

All chemicals were purchased from commercial suppliers and used without further purification. NMR spectra of all synthesized compounds were carried out on an Agilent DD2-400 MHz NMR or Agilent DD2-600 MHz NMR spectrometer with ProbeOne. All chemical shifts of ¹H and ¹³C signals were reported in parts per million using TMS as internal standard at 25 °C and all spectra were calibrated using the respective solvent signal. Mass spectra were recorded on an Advion ExpressIon CMS or Xevo T-QS (Waters) using electrospray ionization. TLC analyses for reaction control were performed on Merck Silica Gel 60 F₂₅₄ TLC plates and visualized using UV light. Analytical HPLC was performed on VWR Hitachi with an Agilent C18 column (Agilent Zorbax 300SB-C18, 100 mm × 4.6 mm) and acetonitrile/water (0.1% TFA each) as mobile phase. Chromatographic separations were performed using automated flash column chromatography on Isolera Four (Biotage) using silica gel cartridges (SNAP KP-Sil; 10 g or 25 g) and reversed phase HPLC system Knauer Azura with Zorbax 300SB-C18 semi-preparative column and acetonitrile/water (0.1% TFA each) as mobile phase. Starting materials such as anhydrous solvents, dimethyl 4-hydroxypyridine-2,6-dicarboxylate (TCI Europe) and 4,13-diaza-18-crown-6 (Merck) were purchased and used as received. Methyl 6-(chloromethyl)picolinate was prepared according to the literature [44 (link)].