Synthesis of 11C-labelled monosaccharides
Sammanfattning: The synthesis of some 11C-labelled (tl/2=20.3 min) monosaccharides is presented. Terminal labelled alkenes were synthesized and selectively oxidized using asymmetric dihydroxylation (AD) and palladium(II)-promoted oxidation. The labelled polyols obtained after the AD were submitted to enzymatic oxidations. The use of polymer-bound triphenylphosphine in the synthesis of three 11C-labelled aromatic alkenes was also investigated.The 11C-labelled alkenes were synthesized from [11C]methyltriphenyl phosphineiodide. Unreacted triphenylphosphine was quenched prior to the AD. In the synthesis of D-[6-11C]glucose and D-[1-11C]mannitol, the protecting groups were removed by acid hydrolysis and purified on high performance liquid chromatography (HPLC). The decay corrected radiochemical yields were 25 % in the synthesis of D-[6-11C]glucose, and 29 % in the synthesis of D-[1-11C]mannitol.In the synthesis of 2-deoxy-D-[1-11C]glucose, the 11C-labelled alkene was oxidized with palladium(II) chloride and water. The resulting labelled aldehyde was deprotected and the product was purified on HPLC. The decay corrected radiochemical yield was 28 %.D-[1-11C]Mannitol and D-[ 1-11C]glucitol were synthesized using a Wittig reactionand an AD. Enzymatic oxidation of the two labelled polyols yielded D-[1-11C]fructose and D-[1-11C]glucose, repectively. D-Mannitol dehydrogenase was used for converting D-[1-11C]mannitol to D-[1-11C]fructose and xylitol oxidase for converting D-[1-11C]glucitol to D-[1-11C]glucose. The decay corrected radiochemical yield was 13 % in the synthesis of D-[1-11C]fructose. In the synthesis of D-[1-11C]glucitol the radiochemical yield was low in the AD affording D-[l-11C]glucose in low yield.In the polymer-bound synthesis of 11C-labelled aromatic alkenes three aldehydes,benzaldehyde, para-nitrobenzaldehyde and para-methoxybenzaldehyde, were used to synthesize the corresponding alkenes. The decay corrected radiochemical yields were 29-65%.
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