Synthesis, effect of substituents on the regiochemistry and equilibrium studies of tetrazolo[1,5-a]pyrimidine/2-azidopyrimidines

• Elisandra Scapin,
• Paulo R. S. Salbego,
• Caroline R. Bender,
• Alexandre R. Meyer,
• Anderson B. Pagliari,
• Tainára Orlando,
• Geórgia C. Zimmer,
• Clarissa P. Frizzo,
• Helio G. Bonacorso,
• Nilo Zanatta and
• Marcos A. P. Martins

Beilstein J. Org. Chem. 2017, 13, 2396–2407, doi:10.3762/bjoc.13.237

• theory (DFT) for energetic and molecular orbital (MO) calculations. Keywords: 5-aminotetrazol; azide–tetrazole equilibrium; 2-azidopyrimidine; β-enaminones; tetrazolo[1,5-a]pyrimidine; trifluoromethylatedtetrazolo[1,5-a]pyrimidines; Introduction Tetrazolo[1,5-a]pyrimidines have attracted attention in

• DMSO-d6. These 1H and 13C NMR analyses of 3d:4d in DMSO-d6 showed a mixture of tetrazolo[1,5-a]pyrimidine 3d and 2-azidopyrimidine 4d, which suggested the existence of a tetrazolo[1,5-a]pyrimidine2-azidopyrimidine equilibrium (3d4d, Figure 3a,b). In solution, the tetrazole–azido equilibrium is

• determine that over 90% of the mixture is in the form of 2-azidopyrimidine 4d in CDCl3. This proves the effect of the solvent in the tetrazolo[1,5-a]pyrimidine2-azidopyrimidine equilibrium. The highly polar DMSO-d6 favors the ring closure to form tetrazolo[1,5-a]pyrimidines in larger quantities (3d:4d in a

The reactions of 2-ethoxymethylidene-3-oxo esters and their analogues with 5-aminotetrazole as a way to novel azaheterocycles

• Marina V. Goryaeva,
• Yanina V. Burgart,
• Marina A. Ezhikova,
• Mikhail I. Kodess and
• Viktor I. Saloutin

Beilstein J. Org. Chem. 2015, 11, 385–391, doi:10.3762/bjoc.11.44

• -methyl-2-azidopyrimidine 2c is not stable and converts into compound 3 during standing on open air for 9 days without a solvent. Compound 3 was obtained also by the reaction of ester 1c with 5-AT in ethanol at room temperature; azidopyrimidine 2с was detected by TLC as an intermediate in this reaction

• ) in tetrazolopyrimidine fragment, as well as cross-peaks between H-6’ proton (δ 9.02 ppm) and C-5’ (δ 120.17 ppm) and C-2’ (δ 163.41 ppm) carbons in azidopyrimidine system supported structure 3. The formation of bis-heterocycle 3 is due to the unique structure of the starting 2-azidopyrimidine 2c