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We have developed 8‐amino‐3‐(2S,5R‐dimethyl‐1‐piperidyl)‐[1,2,4]triazolo[4,3‐a]pyrazine‐5‐[11C]carbonitrile ([11C]MTP38) as a positron emission tomography (PET) tracer for the imaging of phosphodiesterase 7. For the fully automated production of [11C]MTP38 routinely and efficiently for clinical applications, we determined the radiosynthesis procedure of [11C]MTP38 using [11C]hydrogen cyanide ([11C]HCN) as a PET radiopharmaceutical. Radiosynthesis of [11C]MTP38 was performed using an automated 11C‐labeling synthesizer developed in‐house within 40 min after the end of irradiation. [11C]MTP38 was obtained with a relatively high radiochemical yield (33 ± 5.5% based on [11C]CO2 at the end of irradiation, decay‐corrected, n = 15), radiochemical purity (>97%, n = 15), and molar activity (47 ± 12 GBq/μmol at the end of synthesis, n = 15). All the results of the quality control (QC) testing for the [11C]MTP38 injection complied with our in‐house QC and quality assurance specifications. We successfully automated the radiosynthesis of [11C]MTP38 for clinical applications using an 11C‐labeling synthesizer and sterile isolator. Taken together, this protocol provides a new radiopharmaceutical [11C]MTP38 suitable for clinical applications. [ABSTRACT FROM AUTHOR]

A procedure for the synthesis of a11C-labeled oligopeptide containing [1-11C]1,2,3,4-tetrahydro-β-carboline-3-carboxylic acid ([1-11C]Tpi) from the corresponding Trp•HCl-containing peptides has been developed involving a Pictet-Spengler reaction with [11C]formaldehyde. The synthesis of [1-11C]Tpi from Trp and [11C]formaldehyde was examined as a model reaction with the aim of developing a facile and effective method for the labeling of peptides with carbon-11. The Pictet-Spengler reaction of Trp and [11C]formaldehyde in acidic media (TsOH or HCl) afforded the desired [1-11C]Tpi in a moderate radiochemical yield. Herein, the application of a Pictet-Spengler reaction to an aqueous solution of Trp•HCl gave the desired product with a radiochemical yield of 45.2%. The RGD peptide cyclo[Arg-Gly-Asp-D-Tyr-Lys] was then selected as a substrate for the labeling reaction with [11C]formaldehyde. The radiolabeling of a Trp•HCl-containing RGD peptide using the Pictet-Spengler reaction was successful. Furthermore, the remote-controlled synthesis of a [1-11C]Tpi-containing RGD peptide was attempted by using an automatic production system to generate [11C]CH3I. The radiochemical yield of the [1-11C]Tpi-containing RGD at the end of synthesis (EOS) was 5.9 ± 1.9% ( n = 4), for a total synthesis time of about 35 min. The specific activity was 85.7 ± 9.4 GBq/µmol at the EOS. Copyright © 2013 European Peptide Society and John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

We report a novel labeling method for the rapid radiochlorination of aromatic compounds using no-carrier-added short-half-life radioactive chloride ions ([38,39Cl]Cl− and [34mCl]Cl−) and OXONE® (Sigma-Aldrich, Japan) as an oxidation reagent. The reaction of radioactive chloride ions with anisole in the presence of OXONE gave a mixture of p-[*Cl]chloroanisole and o-[*Cl]-chloroanisole, with a radiochemical conversion yield of more than 85% (not decay corrected) and selectivity of 7:3, within 10 min. Regioselective radioactive chlorination was achieved by chlorodestannylation of tributylstannyl compounds to afford the corresponding radiochlorinated compounds ( p-chloroanisole and m-chloroanisole) in satisfactory radiochemical yields (80-95% and 46-65%, respectively). Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

We report a novel labeling method for the rapid radiochlorination of aromatic compounds using no-carrier-added short-half-life radioactive chloride ions ([38,39Cl]Cl− and [34mCl]Cl−) and OXONE® (Sigma-Aldrich, Japan) as an oxidation reagent. The reaction of radioactive chloride ions with anisole in the presence of OXONE gave a mixture of p-[*Cl]chloroanisole and o-[*Cl]-chloroanisole, with a radiochemical conversion yield of more than 85% (not decay corrected) and selectivity of 7:3, within 10 min. Regioselective radioactive chlorination was achieved by chlorodestannylation of tributylstannyl compounds to afford the corresponding radiochlorinated compounds ( p-chloroanisole and m-chloroanisole) in satisfactory radiochemical yields (80-95% and 46-65%, respectively). Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

For the first time tripeptides, Z-AA1-Xaa-AA3-OMe (AA1 and AA3 = Gly or Aib, Xaa = 2Pmg and 2Pyg) were prepared containing α-methyl-α-(2-pyridyl)glycine (2Pmg) and α-(2-pyridyl)glycine (2Pyg) by solid-phase Ugi reaction. These results clearly indicate that for the preparation of tripeptides containing an amino acid with a pyridine ring, the solid-phase Ugi reaction is very useful. NMR analysis clarified that 2Pmg-containing tripeptides adopt a unique conformation with an intramolecular hydrogen bond between 2Pmg-NH and the pyridine nitrogen. However, in the case of Z-Gly-2Pyg-Gly-OMe, the intramolecular hydrogen bonding between 2Pyg-NH and the pyridine nitrogen was not observed, whereas Z-Aib-2Pyg-Aib-OMe adopts a unique conformation with an intramolecular hydrogen bond between 2Pyg-NH and a pyridine nitrogen. Conformational analysis of the tripeptides, Z-AA1-Xaa-AA3-OMe (AA1, AA3 = Gly or Aib, Xaa = α,α-di(2-pyridyl)glycine (2Dpy), α-phenyl-α-(2-pyridyl)glycine (2Ppg), 2Pmg and 2Pyg), clarified that when an α,α-disubstituted glycine with a 2-pyridyl group at an α-carbon atom is introduced into any peptide, an intramolecular hydrogen bond between a pyridine nitrogen and an amide proton is formed and conformational mobility of the peptide backbone is restricted. Copyright © 2005 European Peptide Society and John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]