Purity was estimated to be approximately 99% by gas chromatography/mass spectrometry GC-MS (5973 Networ, Agilent) and nuclear magnetic resonance, NMR (VNMRS600, Varian, Department of Chemistry). 1H NMR (600 MHz, CDCl3): δ4.90 (m, 1H), 4.59 (br, 1H), 4.14 (br, 1H), 3.85 (...
2.2. Methods 1H-NMR measurements were recorded on a BRUKER AV III 300 MHz spectrometer (Brucker Austria GmbH, Vienna, Austria). As reference residual protonated solvents CDCl3: 7.26 ppm, DMSO-d6: 2.50 ppm and CD3OD: 3.31 ppm were used. The chemical shift is given in ppm. Gel permeation ...