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

Abstract [11C]Carbon monoxide in low concentration, palladium complexes, alkyl/aryl iodides, and organostannanes are utilized in the synthesis of twenty alkyl [carbonyl‐11C]ketones. The activated palladium(0) species [Pd{P(o‐Tol)3}2] was generated in situ from tris(dibenzylideneacetone)palladium(0) [Pd2(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 11C‐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[13C‐arbonyl)one 6 was synthesised in order to confirm the position of labelling (δ = 196.7 ppm, CDCl3). The presented approach is an efficient way for synthesising 11C‐labelled alkyl/aryl ketones with acceptable radiochemical yield and is generally applicable in 13C‐labelling syntheses. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)