Radiosynthesis of 1‐[11C] polyhomoallylic fatty acids

Abstract
A facile retro‐synthesis involving the radical chain decarboxylation of the N‐hydroxypyridine‐2‐thione esters of both arachidonic and docosahexaenoic acid was utilized to synthesize (all Z)‐1‐bromononadeca‐4,7,10,13‐tetraene, and (all Z)‐1‐bromoheneicosa‐3,6,9,12,15,18‐hexaene in 60% overall yield. The corresponding polyhomoallylic magnesium bromides were carbonated with [11C]CO2 to afford the 1‐[11C]polyhomoallylic labeled fatty acids in good yield in less than 35 minutes. The final radiochemical purities were found to be in excess of 95% by radio‐HPLC.