New [(18) F]fluorinated 1,2,3-triazolyl amino acid derivatives were efficiently prepared from Huisgen 1,3-dipolar cycloaddition reactions, well known as click reaction. We developed two simultaneous click reactions in one-pot with a simple solid-phase extraction (SPE) purification method. [(18) F]fluoro-1-propyne was obtained at a 45% non-decay corrected radiochemical yield based on the [(18) F]fluoride ion. The one-pot and simultaneous two click reactions were performed with unprotected azido-alkyl amino acid, [(18) F]fluoro-1-propyne, and lipophilic additive alkyne to produce three synthetic amino acid derivatives, AMC-101 ([(18) F]-6a), AMC-102 ([(18) F]-6b), and AMC-103 ([(18) F]-6c) with 29%, 28%, and 24% of non-decay corrected radiochemical yields, respectively. All radiotracers indicated that radiochemical purities were >95% without any residual organic solvent. Our new method involving two click reactions in one-pot showed high radiochemical and chemical purity by easy removal of the residual precursor from the simultaneous two click reactions.

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A chiral aziridine was utilized for the synthesis of the anti-bacterial natural amino acid L-(+)-furanomycin, and its analogues including 5'-epi-furanomycin and norfuranomycin. Key steps of this synthesis are the stereoselective Pd-catalyzed etherification for diallyl ethers and ring closing metathesis.

The present study evaluated the tumoral uptake of the novel synthetic amino acid positron emission tomography (PET) tracers (S)-2-amino-3-(4-([(18) F]fluoromethyl)-1H-1,2,3-triazol-1-yl)propanoic acid (AMC-101), (S)-2-amino-4-(4-([(18) F]fluoromethyl)-1H-1,2,3-triazol-1-yl)butanoic acid (AMC-102), and (S)-2-amino-5-(4-([(18) F]fluoromethyl)-1H-1,2,3-triazol-1-yl)pentanoic acid (AMC-103), all of which are (S)-2-amino-(4-([(18) F]fluoromethyl)-1H-1,2,3-triazol-1-yl)alkyl acids. In vitro cellular uptake was investigated using the rat glioma cell lines 9L and C6. In vitro competitive inhibition tests were performed to identify the involvement of specific amino acid transporters. In vivo dynamic PET images of 9L xenograft tumor-bearing model mice were acquired over 2 h after AMC administration. [(18) F]FDOPA PET studies were performed with and without S-carbidopa pretreatment for comparison. All three AMCs exhibited good in vitro cell uptake through the L and alanine-serine-cysteine transporters and enabled clear tumor visualization on PET, leaving the brain devoid of the tracer. Thirty minutes after injection, the mean tumor standardized uptake values were 1.59 ± 0.05, 1.89 ± 0.27, and 1.74 ± 0.13 for AMC-101, AMC-102, and AMC-103, respectively. Although the tumor uptake values of AMCs were lower than that of [(18) F]FDOPA with S-carbidopa pretreatment, AMCs enabled higher contrast images with lower background activity compared with [(18) F]FDOPA with S-carbidopa pretreatment. Our results indicate the potential uses of these new synthetic amino acids as oncologic radiotracers.