Synthesis of [11C]/(13C)amines viacarbonylation followed by reductive amination

Abstract

Twelve ¹¹C-labelled amines were prepared via¹¹C-carbonylation followed by reductive amination. The ¹¹C-carbonylation was performed in the presence of tetrakis(triphenylphosphine)palladium using aryl iodides or aryl triflates, [¹¹C]carbon monoxide and phenyl-/methylboronic acid. The [¹¹C]ketones formed in this step were then transformed directly into amines by reductive amination using different amines in the presence of TiCl₄ and NaBH₃CN. The ¹¹C-labelled amines were obtained with decay-corrected radiochemical yields in the range 2–78%. The radiochemical purity of the isolated products exceeded 98%. (¹³C)Benzhydryl-phenyl-amine was synthesised and analysed by NMR spectroscopy for confirmation of the labelling position. Specific radioactivity was determined for the same compound. The reference compounds were prepared by reductive amination of ketones using conventional reaction conditions and three of the compounds were novel. The presented approach is a new method for the synthesis of [¹¹C]/(¹³C)amines.