| Abstract
| - As an effort in the development of more flexible 18F-labeling chemistry, we report herein on the use of theCu(I)-catalyzed Huisgen cycloaddition, also known as the “click reaction”, to form 18F-labeled 1,2,3-triazoles.Nucleophilic fluorination of 2-azidoethyl-4-toluenesulfonate followed by distillation provided 2-[18F]fluoroethylazidein 55% radiochemical yield (decay-corrected). 2-[18F]fluoroethylazide was reacted with a small library of terminalalkynes in the presence of excess Cu2+/ascorbate or copper powder. The most reactive alkyne, N-benzylpropynamideprovided nearly quantitative incorporation of 2-[18F]fluoroethylazide after 15 min at ambient temperature, whereasthe majority of the alkyne substrates provided excellent yields of the corresponding 18F-labeled 1,2,3-triazolesfollowing heating to 80 °C. Using the method described, a model peptide was obtained in 92.3 ± 0.3% (n = 3)radiochemical yield (decay-corrected) after purification by semipreparative HPLC.
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