Synthesis of isomers of 18F-labelled amino acid radiopharmaceutical

Inhibition of radical reactions for an improved potassium tert‐butoxide‐promoted 11C‐methylation strategy for the synthesis of α‐11C‐methyl amino acids

“…Benzophenone imine analogs are more stable than benzaldimine analogs, 17 and benzophenone imine-type labeling precursors are therefore more suitable for the radiosynthesis of α-11 C-methyl amino acids. We initially explored the 11 conditions. Several bases were screened against the reaction, including TBAF, TEA, and DBU, but all of these bases failed to provide the desired 11 C-methylated product (Table 1, entries 1-4).…”

“…1,2 Because amino acids are the building blocks of proteins and hormones and intermediates for neurotransmitters and energy metabolism, 1,2 amino acid analogs labeled with 11 C, 18 F, and 13 N have been explored extensively as tool compounds for the imaging of biological phenomenon by positron emission tomography (PET).…”

“…10 However, the number of radiolabeled α-methyl amino acid tracer compounds available for imaging studies is limited, because the vast majority of these compounds are synthesized by the incorporation of a radiohalogen into their side chain. 4,5,11 In contrast, L-[ 11 C]-α-methyl tryptophan ([ 11 C] AMT) 12 and 2-amino- [3-11 C]isobutyric acid ( [3][4][5][6][7][8][9][10][11] C]AIB) 13 were labeled with 11 C at their α-methyl group by the 11 C-methylation of the corresponding Schiff-base-activated amino acid derivatives. The radiolabeling of the core structure of α-methyl amino acids with 11 C could potentially be used as an effective strategy to synthesize a variety of 11 C-labeled α-amino acids and evaluate their biological properties by PET.…”

“…4,5,11 In contrast, L-[ 11 C]-α-methyl tryptophan ([ 11 C] AMT) 12 and 2-amino- [3-11 C]isobutyric acid ( [3][4][5][6][7][8][9][10][11] C]AIB) 13 were labeled with 11 C at their α-methyl group by the 11 C-methylation of the corresponding Schiff-base-activated amino acid derivatives. The radiolabeling of the core structure of α-methyl amino acids with 11 C could potentially be used as an effective strategy to synthesize a variety of 11 C-labeled α-amino acids and evaluate their biological properties by PET. In this study, we have developed an optimized procedure for the 11 C-methylation of Schiff-baseactivated α-amino acid derivatives that can be used for the radiosynthesis of a wide variety of α-11 C-methyl amino acids.…”

“…The radiolabeling of the core structure of α-methyl amino acids with 11 C could potentially be used as an effective strategy to synthesize a variety of 11 C-labeled α-amino acids and evaluate their biological properties by PET. In this study, we have developed an optimized procedure for the 11 C-methylation of Schiff-baseactivated α-amino acid derivatives that can be used for the radiosynthesis of a wide variety of α-11 C-methyl amino acids.…”