Palladium‐Mediated ¹¹C‐Carbonylative Cross‐Coupling of Alkyl/Aryl Iodides with Organostannanes: An Efficient Synthesis of Unsymmetrical Alkyl/Aryl [¹¹C‐<i>carbonyl</i>]Ketones

Abstract

Abstract [ 11 C]Carbon monoxide in low concentration, palladium complexes, alkyl/aryl iodides, and organostannanes are utilized in the synthesis of twenty alkyl [carbonyl‐ 11 C]ketones. The activated palladium(0) species [Pd{P( o ‐Tol) 3 } 2 ] was generated in situ from tris(dibenzylideneacetone)palladium(0) [Pd 2 (dba) 3 ] and a large excess of tri‐ o ‐tolylphosphane [P( o ‐Tol) 3 ]. The Stille coupling reactions were performed in a micro‐autoclave system. Radiochemical yields of 11 C‐labelled alkyl/aryl ketones were in the range of 37–98 % with specific radioactivity up to 300 GBq μmol –1 . Using this method, 4'‐aminoacetophen[ 13 C‐ arbonyl )one 6 was synthesised in order to confirm the position of labelling ( δ = 196.7 ppm, CDCl 3 ). The presented approach is an efficient way for synthesising 11 C‐labelled alkyl/aryl ketones with acceptable radiochemical yield and is generally applicable in 13 C‐labelling syntheses. (© Wiley‐VCH Verlag GmbH &amp; Co. KGaA, 69451 Weinheim, Germany, 2005)