N isotope-labeled amino acids (15N-amino acids) provide a safe and effective tracer tool for studying the synthesis of natural products, protein metabolism, and disease diagnosis and treatment in living organisms. In addition, it is an important synthetic block for the synthesis of 15N-labeled drugs. Currently, 15N-labeled amino acids are generally synthesized by microbial fermentation and chemical reduction amination of ketoacids, but these methods usually require complex steps, high temperature conditions or the use of toxic cyanide, causing energy and environmental problems. Therefore, it is of great significance to develop a green and mild method for the synthesis of 15N-amino acids.
Recently, Zhang's group reported an electrochemical method to synthesize 15N-amino acids from 15N-nitrite and ketonic acids over a commercial nickel foam (NF) cathode in an aqueous solution under ambient conditions. 15N-alanine with a 93% yield was achieved. Impressively, 15N-ammonium, the major byproduct, could be electrooxidized to 15N-nitrite with a yield of 93%, realizing the recycling property and atomic economy of 15N-nitrite. A 15N-nitrite→15NH2OH→15N-oxime→15N-amino acid pathway was revealed by a series of control experiments, in situ attenuated total reflection Fourier transform infrared (in situ A TR-SEIRAS) spectroscopy, and online differential electrochemical mass spectrometry (DEMS). Furthermore, the method was suitable for synthesizing six 15N-amino acids with 68%–95% yields, demonstrating the good universality of this method. A hepatitis treatment drug, 15N-tiopronin, was synthesized using 15N-glycine, highlighting the utility of this method.
The study not only offers a strategy for the room-temperature and green synthesis of 15N-amino acids but also opens a sustainable avenue to construct 15N-labeled compounds.
See the article:
Electrosynthesis of 15N-labeled amino acids from 15N-nitrite and ketonic acids
https://doi.org/10.1007/s11426-023-1613-x
