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A versatile synthetic route to the preparation of 15 N heterocycles
Author(s) -
Chukanov Nikita V.,
Kidd Bryce E.,
Kovtunova Larisa M.,
Bukhtiyarov Valerii I.,
Shchepin Roman V.,
Chekmenev Eduard Y.,
Goodson Boyd M.,
Kovtunov Kirill V.,
Koptyug Igor V.
Publication year - 2019
Publication title -
journal of labelled compounds and radiopharmaceuticals
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.432
H-Index - 47
eISSN - 1099-1344
pISSN - 0362-4803
DOI - 10.1002/jlcr.3699
Subject(s) - chemistry , radiochemistry , combinatorial chemistry , organic chemistry
A robust medium‐scale (approximately 3 g) synthetic method for 15 N labeling of pyridine ( 15 N‐Py) is reported based on the Zincke reaction. 15 N enrichment in excess of 81% was achieved with approximately 33% yield. 15 N‐Py serves as a standard substrate in a wide range of studies employing a hyperpolarization technique for efficient polarization transfer from parahydrogen to heteronuclei; this technique, called SABRE (signal amplification by reversible exchange), employs a simultaneous chemical exchange of parahydrogen and a to‐be‐hyperpolarized substrate (e.g., pyridine) on metal centers. In studies aimed at the development of hyperpolarized contrast agents for in vivo molecular imaging, pyridine is often employed either as a model substrate (for hyperpolarization technique development, quality assurance, and phantom imaging studies) or as a co‐substrate to facilitate more efficient hyperpolarization of a wide range of emerging contrast agents (e.g., nicotinamide). Here, the produced 15 N‐Py was used for the feasibility study of spontaneous 15 N hyperpolarization at high magnetic (HF) fields (7 T and 9.4 T) of an NMR spectrometer and an MRI scanner. SABRE hyperpolarization enabled acquisition of 2D MRI imaging of catalyst‐bound 15 N‐pyridine with 75 × 75 mm 2 field of view (FOV), 32 × 32 matrix size, demonstrating the feasibility of 15 N HF‐SABRE molecular imaging with 2.4 × 2.4 mm 2 spatial resolution.