The azide/tetrazole equilibrium: an investigation in the series of furo- and thieno[2,3-e]tetrazolo[3,2-d]pyrimidine derivatives

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• 作者：Samvel N. Sirakanyan^a ; ^{shnnr@mail.ru" class="auth_mail" title="E-mail the corresponding author} ; Domenico Spinelli^b ; ^{domenico.spinelli@unibo.it" class="auth_mail" title="E-mail the corresponding author} ; Athina Geronikaki^c ; ^{geronik@pharm.auth.gr" class="auth_mail" title="E-mail the corresponding author} ; Viktor G. Kartsev^d ; ^{vkartsev@ibscreen.chg.ru" class="auth_mail" title="E-mail the corresponding author} ; Henrik A. Panosyan^e ; ^{henry@msrc.am" class="auth_mail" title="E-mail the corresponding author} ; Armen G. Ayvazyan^e ; Rafael A. Tamazyan^e ; Vincenzo Frenna^f ; ^{vincenzo.frenna@unipa.it" class="auth_mail" title="E-mail the corresponding author} ; Anush A. Hovakimyan^a
• 关键词：Azide/tetrazole equilibrium ; Furo(thieno)[2 ; 3-e]tetrazolo[1 ; 5-c]pyrimidines ; Structure effect ; Solvent effect ; Temperature effect
• 刊名：Tetrahedron
• 出版年：2016
• 出版时间：21 April 2016
• 年：2016
• 卷：72
• 期：16
• 页码：1919-1927
• 全文大小：760 K

文摘

Starting from 7(8)-chlorofuro(thieno)[3,2-d]pyrimidines class="boldFont">1, the corresponding 7(8)-hydrazinofuro(thieno)[3,2-d]pyrimidines class="boldFont">2 were obtained by reaction with hydrazine. By treatment with nitrous acid, compounds class="boldFont">2 gave fused furo- and thieno[2,3-e]tetrazolo[1,5-c]pyrimidines class="boldFont">3T and class="boldFont">4T in excellent yields, which in solution exist in equilibrium with 7(8)-azidofuro(thieno)[3,2-d]pyrimidines class="boldFont">3A and class="boldFont">4A. Compounds class="boldFont">3T/class="boldFont">3A and class="boldFont">4T/class="boldFont">4A represent useful substrates for investigating the azide/tetrazole equilibrium: it has been examined as a function of solvent, temperature, and their structure. We have observed that, in solution, in both class="boldFont">3 and class="boldFont">4 the equilibrium was strongly affected by the solvent used. In contrast, X-ray analysis has shown that both thieno[2,3-e]tetrazolo[1,5-c]pyrimidines and furo[2,3-e]tetrazolo[1,5-c]pyrimidines in solid state exist only in the tetrazole tautomeric form. For this reason the equilibrium constants and the relevant thermodynamic parameters have been calculated in different solvents: finally excellent logarithmic plots of ΔG° values versus dielectric constants have been observed (slopes 10.00÷10.57; correlation coefficients 0.9962÷0.9999) for a series (seven examples) of furo compounds class="boldFont">3.