| When combined with sucrose to produce highly fluorinated sucrose polyesters (HFSPE's), fluorinated fatty acids with at least 10 fluorine atoms per chain may have possible use in the preparation of novel image enhancement agents for hyperpolarized xenon Magnetic Resonance Imaging (MRI).; The synthesis of Z-11,11,12,12,13,13,14,14,15,15,16,16,17,17,18,18,18-heptadecafluoro-octadec-8-enoic acid was performed via a procedure which employs a Wittig reaction as its key step and generates the Z isomer almost exclusively. The structure was confirmed by 13C NMR and NOESY spectra.; The stereospecific synthesis of Z-13,13,14,14,15,15,16,16,17,17,18,18,18-tridecafluoro-octadec-9-enoic acid (oleic acid-F13) was carried out through a seven-step synthesis. Again a Wittig reaction is the key chain-lengthening step, however the carbonyl component and the phosphonium salt component are reversed from the previously employed procedure and the carboxylic acid function is included in the phosphonium component. The 19F Nuclear Magnetic Resonance (NMR) spectrum of oleic acid-F13 has been recorded and unambiguous chemical shift assignments have been made via 19F-19F COSY spectroscopy. (Abstract shortened by UMI.)... |
