Long-Range 1H鈥?sup>15N J Couplings Providing a Method for Direct Studies of the Structure and Azide鈥揟etrazole Equilibrium in a Series of Azido-1,2,4-triazines and Azidopyrimidi

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• 作者：Tatyana S. Shestakova ; Zakhar O. Shenkarev ; Sergey L. Deev ; Oleg N. Chupakhin ; Igor A. Khalymbadzha ; Vladimir L. Rusinov ; Alexander S. Arseniev
• 刊名：The Journal of Organic Chemistry
• 出版年：2013
• 出版时间：July 19, 2013
• 年：2013
• 卷：78
• 期：14
• 页码：6975-6982
• 全文大小：456K
• 年卷期：v.78,no.14(July 19, 2013)
• ISSN：1520-6904

文摘

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鈥搕etrazole equilibrium could lead to the formation of two tetrazoles (T, T鈥?/b>) and one azide (A) isomer for each compound. The incorporation of the ¹⁵N label led to the appearance of long-range ¹H鈥?sup>15N coupling constants (J_HN), which can be measured easily by using amplitude-modulated 1D ¹H spin鈥揺cho experiments with selective inversion of the ¹⁵N nuclei. The observed J_HN 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鈥? 4*T鈥?/b> 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 J_HN couplings in ¹⁵N-labeled compounds provides a simple and efficient method for direct NMR studies of the azide鈥搕etrazole equilibrium in solution.