Nucleophilic [18F]Fluorination and subsequent decarbonylation of methoxy-substituted nitro- and halogen-benzenes activated by one or two formyl groups
✍ Scribed by Bin Shen; Dirk Löffler; Gerald Reischl; Hans-Jürgen Machulla; Klaus-Peter Zeller
- Publisher
- John Wiley and Sons
- Year
- 2010
- Tongue
- French
- Weight
- 199 KB
- Volume
- 53
- Category
- Article
- ISSN
- 0022-2135
No coin nor oath required. For personal study only.
✦ Synopsis
Abstract
As model reactions for the introduction of ^18^F into protected aromatic amino acids, the replacement of NO~2~, Cl, Br and F by [^18^F]fluoride in 2‐isophthalaldehyde and 2‐terephthalaldehyde derivatives which model ^18^F‐DOPA and ^18^F‐tyrosine was investigated by comparing labelling yields and reaction rates with those of corresponding mono‐aldehyde compounds. All isophthalaldehydes showed maximum radiochemical yields (79 to 86%) at 140°C and in comparison with the corresponding mono‐aldehydes the reaction proceeded faster. At lower temperature the reaction already resulted in high yields, e.g. 2‐nitroisophthalaldehyde was labelled with a yield of 78% at 25°C after 7 min, whereas 2‐nitrobenzaldehyde only reached a yield of 1.7% under the same reaction conditions. The ^18^F/NO~2~ exchange in nitroterephthalaldehydes proceeded more slowly and with lower radiochemical yields when compared with corresponding isophthalaldehydes and monoaldehydes. The decarbonylation of ^18^F‐labelled aromatic dialdehydic compounds with 4 eq. of Wilkinson's catalyst at 150°C in benzonitrile resulted in high yields, e.g. 2‐[^18^F]fluoro‐5‐methoxyisophthalaldehyde and 4‐[^18^F]fluoro‐2‐methoxy‐5‐methylisophthalaldehyde were decarbonylated efficiently with yields of 67±3% and 72±2%, respectively. Copyright © 2010 John Wiley & Sons, Ltd.