1. Long-range 1H-15N J couplings providing a method for direct studies of the structure and azide-tetrazole equilibrium in a series of azido-1,2,4-triazines and azidopyrimidines
- Author
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Oleg N. Chupakhin, Tatyana S. Shestakova, Vladimir L. Rusinov, Sergey L. Deev, Igor A. Khalymbadzha, Alexander S. Arseniev, and Zakhar O. Shenkarev
- Subjects
Magnetic Resonance Spectroscopy ,MOLECULAR STRUCTURE ,Tetrazoles ,REFERENCE STANDARDS ,PROTON ,ISOMERS ,Medicinal chemistry ,chemistry.chemical_compound ,STANDARD ,AZIDES ,CHEMISTRY ,X RAY CRYSTALLOGRAPHY ,PYRIMIDINES ,Organic chemistry ,Tetrazole ,ELECTROSPRAY ,STRUCTURE ANALYSIS ,ISOMERIZATION ,chemistry.chemical_classification ,Nitrous acid ,Molecular Structure ,COUPLING CONSTANTS ,Triazines ,NMR STUDIES ,SIGNAL TRANSDUCTION ,NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY ,AMPLITUDE-MODULATED ,Nuclear magnetic resonance spectroscopy ,HYDROGEN ,Reference Standards ,NITROGEN 15 ,Azine ,1,2,4 TRIAZINE DERIVATIVE ,1H-TETRAZOLE ,MAGNETIC RESONANCE SPECTROSCOPY ,PYRROLE ,Protons ,Azides ,LOW CONCENTRATIONS ,J COUPLING ,SYNTHESIS ,CARBON NUCLEAR MAGNETIC RESONANCE ,TETRAZOLE DERIVATIVE ,TETRAZOLES ,PYRIMIDINE DERIVATIVE ,DIMETHYL SULFOXIDE ,PROTONS ,ARTICLE ,NITROGEN ISOTOPES ,TRIAZINES ,Coupling constant ,Coupling ,ISOMER ,Nitrogen Isotopes ,AZIDE ,NITROGEN NUCLEAR MAGNETIC RESONANCE ,CHEMICAL STRUCTURE ,Organic Chemistry ,1,2,4 TRIAZINE ,1H TETRAZOLE ,NITROGEN ,PROTON NUCLEAR MAGNETIC RESONANCE ,NITROUS ACID ,Pyrimidines ,chemistry ,AMPLITUDE MODULATION ,Azole ,Azide ,TRIAZINE DERIVATIVE ,1,2,4-TRIAZINE ,SPIN ECHO - Abstract
The selectively 15N labeled azido-1,2,4-triazine 2*A and azidopyrimidine 4*A were synthesized by treating hydrazinoazines with 15N-labeled nitrous acid. The synthesized compounds were studied by 1H, 13C, and 15N NMR spectroscopy in DMSO, TFA, and DMSO/TFA solutions, where the azide-tetrazole equilibrium could lead to the formation of two tetrazoles (T, T′) and one azide (A) isomer for each compound. The incorporation of the 15N label led to the appearance of long-range 1H-15N coupling constants (JHN), which can be measured easily by using amplitude-modulated 1D 1H spin-echo experiments with selective inversion of the 15N nuclei. The observed JHN patterns enable the unambiguous determination of the mode of fusion between the azole and azine rings in the two groups of tetrazole isomers (2*T′, 4*T′ and 2*T, 4*T), even for minor isoforms with a low concentration in solution. However, the azide isomers (2*A and 4*A) are characterized by the absence of detectable J HN coupling. The analysis of the JHN couplings in 15N-labeled compounds provides a simple and efficient method for direct NMR studies of the azide-tetrazole equilibrium in solution. © 2013 American Chemical Society.
- Published
- 2013