What is it about?

By taking advantage of 1D NMR (1H and 13C NMR) and 2D NMR (NOESY) spectroscopic analyses of NMR data in dissolved DMSO-d6 at room tempertaure, we indicated the presence of acetohydrazine derivatives as a mixture of two conformers. The critical parameter is a slow rotation around the N-acyl bond, with the N-H bond being in a cis or trans position with respect to the carbonyl bond, leading respectively to syn-periplanar E (sp E) or anti-periplanar E (ap E) conformers.

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Why is it important?

The work deals with the synthesis of a series of heteroaromatic compounds including a particular functional group, N-acyl hydrazone that is subject to dynamic isomerism, a phenomenon that the work identifies, thanks to the NMR tool. Despite the effect of temperature on this equilibrium position, mainly in DMSO, considering its boiling point. A variable temperature NMR experiment was done but the coalescence and the activation barrier of the conformational equilibrium did not show any difference from what we found as results.


Our work shows an interesting and strong milestone to get the major synperiplanar E conformer. Given the approach, the features that it enables, and the fact that the basic concept is broadly adaptable to other scaffolds, we believe that our findings are important and broadly interesting for researchers. This series of new N-acylhydrazone derivatives containing the thio-imidazo[1,2-a]pyridine scaffold could access to a new class of compounds with potential biological activities.

Souleymane Coulibaly
Universite Felix Houphouet-Boigny

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This page is a summary of: Synthesis and characterization of novel conformers of ( E ) ‐ 2‐(3‐nitro‐ H ‐imidazo[1,2‐ a ]pyridin‐2‐ylthio)‐ N..., Magnetic Resonance in Chemistry, September 2022, Wiley,
DOI: 10.1002/mrc.5308.
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