Steric and electronic effects on the 1H hyperpolarization of substituted pyridazines by signal amplification by reversible exchange was written by Rayner, Peter j.;Burns, Michael j.;Fear, Elizabeth j.;Duckett, Simon b.. And the article was included in Magnetic Resonance in Chemistry in 2021.Electric Literature of C5H6N2O This article mentions the following:
Utility of the pyridazine motif is growing in popularity as pharmaceutical and agrochem. agents. The detection and structural characterization of such materials is therefore imperative for the successful development of new products. Signal amplification by reversible exchange (SABRE) offers a route to dramatically improve the sensitivity of magnetic resonance methods, and we apply it here to the rapid and cost-effective hyperpolarization of substituted pyridazines. The 33 substrates investigated cover a range of steric and electronic properties and their capacity to perform highly effective SABRE is assessed. We find the method to be tolerant to a broad range of electron donating and withdrawing groups; however, good sensitivity is evident when steric bulk is added to the 3- and 6-positions of the pyridazine ring. We optimize the method by reference to a disubstituted ester that yields signal gains of >9000-fold at 9.4 T (>28% spin polarization). In the experiment, the researchers used many compounds, for example, 3-Methoxypyridazine (cas: 19064-65-4Electric Literature of C5H6N2O).
3-Methoxypyridazine (cas: 19064-65-4) belongs to pyridazine derivatives. The pyridazine structure is also found within the structure of several drugs such as cefozopran, cadralazine, minaprine, pipofezine, and hydralazine. The unsubstituted pyridazines are more resistant to eletrophilic substitution due to the nature of withdrawal of electron density from the ring by two heteroatoms, while the related electron deficiency of the ring makes pyridazine more easily attacked by nucleophiles.Electric Literature of C5H6N2O
Referemce:
Pyridazine – Wikipedia,
Pyridazine | C4H4N2 – PubChem