title: [18F]fluorination/decarbonylation: new route to aryl [18F]fluorides.
abstract: A new route to aryl [18F]fluorides without electron withdrawing ring substituents has been developed. [18F]Fluorobenzaldehydes, prepared from no-carrier-added (NCA) [18F]fluoride using nucleophilic aromatic substitution of fluoro or nitro groups, were decarbonylated using palladium on charcoal (Pd-C). By this approach 2-methoxy-4-nitrobenzaldehyde was converted to NCA 3-[18F]fluorophenol (25-30%, EOB) and 4-fluoro-2-methoxy-5-methylbenzaldehyde to carrier-added (CA) 3-[18F]fluoro-4-methylphenol (30-40%, EOB). Overall synthesis time was about 2 h. Since the 4-fluoro-2-methoxy-5-methylbenzaldehyde was in turn prepared by methylation and regiospecific formylation of 3-fluoro-4-methylphenol, the overall process represents use of a removable activating group for nucleophilic aromatic substitution with [18F]fluoride for preparation of CA and NCA aryl [18F]fluorides.
authors.affiliation: Department of Internal Medicine, University of Michigan, Ann Arbor 48109.
authors.forename: P K
authors.initials: PK
authors.lastname: Chakraborty
authors.forename: M R
authors.initials: MR
authors.lastname: Kilbourn
mesh_terms: D006845:Hydrocarbons, Fluorinated / Q000138:chemical synthesis*; D007553:Isotope Labeling
chemical_list: D006845:Hydrocarbons, Fluorinated