The Use of Lithium Amides in the Palladium‐Mediated Synthesis of [ Carbonyl ‐ 11 C]Amides

Weakly nucleophilic amines were converted into the corresponding lithium amides and used in either one‐ or two‐pot palladium‐mediated reactions with [ 11 C]carbon monoxide and aryl iodides. It was found that palladium acyl complexes may be prepared in a separate step and have sufficient lifetime to be used in a subsequent reaction with a nucleophile. This two‐pot procedure was used for the labelling synthesis of eleven amides (nine of which are analogues of WAY‐100635, a 5‐HT 1A radioligand) from weakly nucleophilic amines. The results were compared to a direct one‐pot procedure using lithium amides. Both approaches extend the scope of palladium‐mediated carbonylation using [ 11 C]carbon monoxide and aryl iodides allowing use of weakly nucleophilic amines. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)