1,2,4-Triazolo- and Tetrazolo[x,y-z]pyrimidines

El-Ashry, E. S. H.; Rashed, N.

doi:10.1016/s0065-2725(08)60316-5

Cited by 32 publications

(8 citation statements)

References 144 publications

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“…Synthesis. Derivatives of 1,2,4-triazolo[1,5- a ]pyrimidine [ 30 ], 1,2,4-triazolo[5,1- c ][1,2,4]triazinone [ 31 ] and tetrazolo[1,5- b ][1,2,4]triazinone [ 32 ] can be obtained by the fusion of an azine ring to an azole fragment. This method can be used for the selective incorporation of 15 N atoms in different azolo-azines.…”

Section: Resultsmentioning

confidence: 99%

¹⁵N-Labelling and structure determination of adamantylated azolo-azines in solution

Деев¹,

Paramonov²,

Шестакова³

et al. 2017

Beilstein J. Org. Chem.

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Determining the accurate chemical structures of synthesized compounds is essential for biomedical studies and computer-assisted drug design. The unequivocal determination of N-adamantylation or N-arylation site(s) in nitrogen-rich heterocycles, characterized by a low density of hydrogen atoms, using NMR methods at natural isotopic abundance is difficult. In these compounds, the heterocyclic moiety is covalently attached to the carbon atom of the substituent group that has no bound hydrogen atoms, and the connection between the two moieties of the compound cannot always be established via conventional 1H-1H and 1H-13C NMR correlation experiments (COSY and HMBC, respectively) or nuclear Overhauser effect spectroscopy (NOESY or ROESY). The selective incorporation of 15N-labelled atoms in different positions of the heterocyclic core allowed for the use of 1H-15N (J HN) and 13C-15N (J CN) coupling constants for the structure determinations of N-alkylated nitrogen-containing heterocycles in solution. This method was tested on the N-adamantylated products in a series of azolo-1,2,4-triazines and 1,2,4-triazolo[1,5-a]pyrimidine. The syntheses of adamantylated azolo-azines were based on the interactions of azolo-azines and 1-adamatanol in TFA solution. For azolo-1,2,4-triazinones, the formation of mixtures of N-adamantyl derivatives was observed. The J HN and J CN values were measured using amplitude-modulated 1D 1H spin-echo experiments with the selective inversion of the 15N nuclei and line-shape analysis in the 1D 13С spectra acquired with selective 15N decoupling, respectively. Additional spin–spin interactions were detected in the 15N-HMBC spectra. NMR data and DFT (density functional theory) calculations permitted to suggest a possible mechanism of isomerization for the adamantylated products of the azolo-1,2,4-triazines. The combined analysis of the J HN and J CN couplings in 15N-labelled compounds provides an efficient method for the structure determination of N-alkylated azolo-azines even in the case of isomer formation. The isomerization of adamantylated tetrazolo[1,5-b][1,2,4]triazin-7-ones in acidic conditions occurs through the formation of the adamantyl cation.

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Section: Resultsmentioning

confidence: 99%

¹⁵N-Labelling and structure determination of adamantylated azolo-azines in solution

Деев¹,

Paramonov²,

Шестакова³

et al. 2017

Beilstein J. Org. Chem.

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“…These heterocycles have a structure similar to that of purine and adenine, their fused ring system differing in having the pyrimidine nitrogen atom in a bridgehead position. [3][4][5] Recently anti-tumor activity of cis-[Pt II (Hmtpo-N 3 ) 2 Cl 2 ]ؒ 2H 2 O where HmtpO = 4,7-H-5-methyl-7-oxo-1,2,4-triazolo-[1,5-a]pyrimidine was reported. 6 Considering that also palladium() co-ordination compounds are promising in cancer therapy, 7 we have decided to study a class of cis-PdL 2 Cl 2 type complexes (L = tp or its derivative).…”

Section: Introductionmentioning

confidence: 99%

Palladium(II) chloride complexes with 1,2,4-triazolo[1,5-a]pyrimidines: X-ray, 15N–1H NMR and 15N CP MAS studies

Szłyk

Grodzicki

Pazderski

et al. 2000

J. Chem. Soc., Dalton Trans.

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The crystal structure of [Pd(dbtp) 2 Cl 2 ]ؒ0.5 C 2 H 5 OH 4c was resolved by X-ray diffraction analysis, exhibiting monomeric, nearly square-planar cis geometry and N(3) co-ordination. A small tetrahedral distortion from the co-ordination plane was observed. The Pd-Cl distances are 2.276(1) and 2.283(1) Å, and Pd-N 2.042(3) and 2.040(3) Å. Spectroscopic measurements (UV-VIS, IR, NMR) suggested analogous structures for 1, 2 and 3. Compounds 4a and 4b are most likely rotational isomers in solution and distortional isomers in the solid state. 15 N-1 H heteronuclear correlation NMR was measured for 2, 4a and 4b whereas 1 and 3 were characterized with 13 C and 15 N CP MAS. Significant shielding of the co-ordinated N(3) and adjacent C(2) or C(3a) nuclei was observed.

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“…Ligand (1) (Figure 1) is interesting for studying, because the purine donor atoms system [(N (7) and N (9)] are blocked by methyl groups and coordination sites are available for the pyrimidine ring system. In the literature there are only a few reports of coordination via N(3) or N(1) atoms in adenine [5][6][7].…”

Section: Introductionmentioning

confidence: 99%

“…In the literature there are only a few reports of coordination via N(3) or N(1) atoms in adenine [5][6][7]. Possible coordination by N(7) in (1) is also unfavorable due to likely steric hindrance from the methyl groups at C(2) and C (6).…”

Section: Introductionmentioning

confidence: 99%

Synthesis and spectroscopic characterization of palladium(II) complexes with 6,8-dimethylimidazo[1,5-a]-1,3,5-triazin-4(3H)-one and 6,8-dimethyl-2-thioxo-2,3-dihydroimidazo-[1,5-a]-1,3,5-triazin-4(1H)-one

Łakomska¹,

Barwiołek²,

Szłyk³

et al. 2006

Transition Met Chem

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Synthesis and spectroscopic characterization of palladium(II) complexes with 6,8-dimethylimidazo[1,5-a]-1,3,5-triazin-4(3H)-one and 6,8-dimethyl-2-thioxo-2,3-dihydroimidazo-[1,5-a]-1,3,5-triazin-4(1H)-one Abstract The preparation and spectroscopic study ( 1 H, 13 C, 15 NNMR, 13 CP MAS NMR, IR) of new Pd II complexes with 6,8-dimethylimidazo[1,5-a]-1,3,5-triazin-4(3H)-one (6,8-DiMe-4-O-IMT) (1) and 6,8-dimethyl-2-thioxo-2,3-dihydroimidazo[1,5-a]-1,3,5-triazin-4(1H)-one (6,8-DiMe-4-O-2-S-IMT) (2) is reported. The spectroscopic data indicate a square planar geometry with two N(7) bonded heterocycles and two cis-chloride anions. The final product of the thermal decomposition of cis-PdCl 2 (6,8-DiMe-4-O-IMT) 2 (3) is metallic Pd, whereas for cis-PdCl 2 (6,8-DiMe-4-O-2-S-IMT) 2 (4) it is metallic Pd plus C.

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1,2,4-Triazolo- and Tetrazolo[x,y-z]pyrimidines

Cited by 32 publications

References 144 publications

¹⁵N-Labelling and structure determination of adamantylated azolo-azines in solution

¹⁵N-Labelling and structure determination of adamantylated azolo-azines in solution

Palladium(II) chloride complexes with 1,2,4-triazolo[1,5-a]pyrimidines: X-ray, 15N–1H NMR and 15N CP MAS studies

Synthesis and spectroscopic characterization of palladium(II) complexes with 6,8-dimethylimidazo[1,5-a]-1,3,5-triazin-4(3H)-one and 6,8-dimethyl-2-thioxo-2,3-dihydroimidazo-[1,5-a]-1,3,5-triazin-4(1H)-one

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1,2,4-Triazolo- and Tetrazolo[x,y-z]pyrimidines

Cited by 32 publications

References 144 publications

15N-Labelling and structure determination of adamantylated azolo-azines in solution

15N-Labelling and structure determination of adamantylated azolo-azines in solution

Palladium(II) chloride complexes with 1,2,4-triazolo[1,5-a]pyrimidines: X-ray, 15N–1H NMR and 15N CP MAS studies

Synthesis and spectroscopic characterization of palladium(II) complexes with 6,8-dimethylimidazo[1,5-a]-1,3,5-triazin-4(3H)-one and 6,8-dimethyl-2-thioxo-2,3-dihydroimidazo-[1,5-a]-1,3,5-triazin-4(1H)-one

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¹⁵N-Labelling and structure determination of adamantylated azolo-azines in solution

¹⁵N-Labelling and structure determination of adamantylated azolo-azines in solution