Fully automated synthesis of 13N-labeled nitrosothiols

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Microfluidics has recently emerged as a useful alternative to traditional methods for the preparation of radiotracers labelled with positron emitters. Up to date, microfluidics technology has been applied to the radiosynthesis of 18F‐labelled and 11C‐labelled compounds; however, application to other shorter‐lived positron emitters has not been investigated. The radiosynthesis of S‐[13N]nitrosothiols and N‐[13N]nitrosamines was approached in microfluidic system by reaction of the corresponding thiol or secondary amine, respectively, with [13N]NO2− in the presence of mineral acid. The radiosynthesis of azo compounds was carried out by reaction of the same labelling agent with primary aromatic amines in acidic media to yield the corresponding diazonium salts, which were further reacted with aromatic amines and alcohols to yield the corresponding 13N‐labelled azo compounds. Radiochemical conversion values for S‐[13N]nitrosothiols and 13N‐labelled azo compounds calculated from chromatographic profiles improved our previous results by using conventional methods. The formation of N‐[13N]nitrosamines could not be detected, independently of experimental conditions. In conclusion, the preparation of S‐[13N]nitrosothiols and 13N‐labelled azo compounds was successfully achieved by using microfluidics technology. Higher radiochemical conversions than those previously reported using conventional synthetic strategies have been obtained. Copyright © 2012 John Wiley & Sons, Ltd.

“… Solid phase support results have been obtained from Gómez‐Vallejo et al . RCC, radiochemical conversion.…”

Section: Resultsmentioning

confidence: 59%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Synthesis of ¹³N‐labelled radiotracers by using microfluidic technology

Gaja

Gómez‐Vallejo

Cuadrado‐Tejedor

et al. 2012

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“…After the reduction, the reaction of [ 13 N]nitrite with glutathione in the presence of hydrochloric acid led to S ‐[ 13 N]nitrosoglutathione with a sufficient RCY of 24% in a short production time of 3 minutes . The synthesis of S ‐[ 13 N]nitrosothiols (cf Scheme , pathway I) has been fully automated by trapping the [ 13 N]nitrite on an anion exchange resin followed by a nitrosation reaction on the cartridge . The same method was also applied for the preparation of several [ 13 N]nitrosamines (cf Scheme , pathway I) …”

Section: Nitrogen‐13mentioning

confidence: 99%

Labelling with positron emitters of pnicogens and chalcogens

Neumaier

2017

The increasing importance of the positron emission tomography (PET) in clinical diagnosis led to the development of a multitude of radiotracers labelled with positron‐emitting radionuclides of groups 15 (pnicogens) and 16 (chalcogens) of the periodic table of elements. The positron emitters of the endogenous occurring elements nitrogen, phosphorus, oxygen, and sulphur are characterized by very short half‐lives compared with the most commonly used PET radionuclides carbon‐11 or fluorine‐18. Therefore, the potential of their synthesis and possible applications in PET is challenging and limited. On the other hand, the nonstandard positron emitters arsenic‐72, arsenic‐74, and selenium‐73 have half‐lives in the range of hours to days and, thus, are of interest for PET studies of processes with long biological half‐lives, but novel methods have to be developed for their application, especially in the no‐carrier‐added state. This review summarizes recent research concerning the positron emitters of pnicogens and chalcogens for radiolabelling applications.

“…35 The production of the radioactive precursor [ . 36 The preparation of 13 N-labeled nitrosothiols was recently reported using microfluidics technology. 60 In general terms, under similar experimental conditions, higher radiochemical conversion values were obtained when compared with solid phase support synthesis in similar overall reaction times.…”

Section: N]glutamic Acid and L-[mentioning

confidence: 99%

Nitrogen‐13: historical review and future perspectives

Gómez‐Vallejo

Gaja²,

Gona³

et al. 2014

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Positron emission tomography is an ultra-sensitive, in vivo molecular imaging technique that allows the determination of the spatiotemporal distribution of a positron emitter labeled radiotracer after administration into living organisms. Among all existing positron emitters, (18) F has been by far the most widely used both in clinical diagnosis and in preclinical investigation, while the use of (11) C significantly increased after the 1980s because of the widespread installation of biomedical cyclotrons. The use of other shorter-lived positron emitters such as (13) N (T1/2 = 9.97 min) has been historically more restricted. Paradoxically, its stable isotope ((14) N) is present in many biological active molecules; consequently, the development of strategies for the efficient incorporation of (13) N into radiotracers would represent an interesting alternative to (11) C- and (18) F-labeling. In the current paper, the developments related to (13) N chemistry are reviewed, including different production routes of primary precursors and their applications to the preparation of more complex (13) N-labeled molecules. The current situation and future perspectives are also briefly discussed.