Ring-chain tautomerism in 2-substituted 1,2,3,4-tetrahydroquinazolines A 1H, 13C and 15N NMR study

Sinkkonen, Jari; Зеленин, K. Н.; Potapov, A. A.; Lagoda, I. V.; Alekseyev, V. V.; Pihlaja, Kalevi

doi:10.1016/s0040-4020(03)00148-0

Cited by 48 publications

(34 citation statements)

References 24 publications

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“…Similar reactions have been reported before and the related ring-chain tautomerism has been studied for reactions of 2-aminomethylaniline with a large number of aldehydes and ketones. [15,16] Further inspection of the NMR spectra of 3 may shed light on its structure. Indeed, while the signal of the two methylene protons in 2 appears as a sharp singlet at δ = 4.75 ppm, two doublet corresponding to these two protons (H 1 , H 1 Ј, Scheme 3) in 3 were found at δ = 3.93 and 4.05 ppm with a geminal coupling of 16.5 Hz.…”

Section: Figurementioning

confidence: 99%

Syntheses, Structures, and Biological Activity of Ni^II, Pd^II, and Pt^II Complexes with New Tetradentate Benzamidine Ligands

Nguyen

Abram

et al. 2015

Zeitschrift anorg allge chemie

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Section: Figurementioning

confidence: 99%

Syntheses, Structures, and Biological Activity of Ni^II, Pd^II, and Pt^II Complexes with New Tetradentate Benzamidine Ligands

Nguyen

Abram

et al. 2015

Zeitschrift anorg allge chemie

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“…9 The absence of the signals corresponding to the most acidic protons, i.e. the corresponding to OH phenol and NH sulphonamide groups, demonstrates the dianionic behavior of the ligand.…”

Section: Spectroscopyc Characterisation Of the Complexesmentioning

confidence: 99%

Structural variety of zinc and copper complexes based on a 2,3-disubstituted 1,2,3,4-tetrahydroquinazoline ligand

et al. 2012

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The ring-chain tautomerism of 2-(3-tosyl-1,2,3,4-tetrahydroquinazolin-2-yl)quinolin-8-ol (H(2)L(ring)) has been exploited to produce mononuclear complexes or, alternatively, dinuclear complexes, as desired, by varying the stoichiometry of the ligand. Cu(2+) and Zn(2+) stabilise the ring tautomeric form of the ligand in their mononuclear complexes M(HL(ring))(2). The structural characterisation of Zn(HL(ring))(2)·2MeOH·0.5H(2)O shows O,N-donor behaviour of the ring tautomer. The 1,2,3,4-tetrahydroquinazoline undergoes a ring-opening reaction upon formation of phenoxo-bridged dinuclear complexes M(2)(L(chain))(2) in which the chain tautomer is acting as O,N,N,N-donor. The crystal structure of Cu(2)(L(amide))(L(quinazoline))(MeOH)·2MeOH evidenced the sensitivity of H(2)L(ring) to the copper-mediated aerobic oxidation, which results in two derivatives of the ligand, a quinazoline and an amide. The quinazoline ligand is acting as monoanionic and mononucleating through its O,N,N binding site, while the amide ligand behaves as a trianionic and binucleating through its O,N,N,N and O,O binding sites in Cu(2)(L(amide))(L(quinazoline))(MeOH)·2MeOH.

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“…A detailed explanation about the conformational search is given in the experimental section. From the low-energy conformations obtained for both diasteromers R/R and R/S we calculated the shielding tensors using the GIAO approach 33,34 from the program Gaussian 03. 35 Our study also includes the calculation of 13 C-NMR chemical shift for the diasteroisomers (R/R; R/S; S/R and S/S) by using the gauge independent atomic orbital (GIAO) approximation.…”

Section: Theoretical Calculationsmentioning

confidence: 99%

“…Minima were characterized through harmonic frequency analysis employing B3LYP/6-31 G(d) calculations. GIAO [33][34] (gauge independent atomic orbital) computations were carried out using B3LYP/6-31G(d) calculations. All the calculations reported here were performed using the Gaussian 03 Program.…”

Section: E=e(3x2x2x2x2)=48 (3)mentioning

confidence: 99%

“…Figure 3S shows a spatial view of the lowest-energy conformation obtained for compound 4g 2 . From the low-energy conformations obtained for both diasteromers R/R and R/S we calculated the shielding tensors using the GIAO approach 33,34 from the program Gaussian 03. 35 From the tensors we obtain the value of calculated chemical shift (calc) for each C atom of each isomer, using the following expression (Eq.…”

Section: E=e(3x2x2x2x2)=48 (3)mentioning

confidence: 99%

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Easy synthesis of new series of pteridine analogs: di- and tetra-hydropyrimido[4,5-d]pyrimidines via 5-pyrimidinecarbaldehydes

Torre¹,

Nogueras²,

Borkowski³

et al. 2014

Arkivoc

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Straightforward procedures allow a quick access to these compounds. The dihydro derivatives were prepared means of a final cyclocondensation carried out with orthoesters, catalysed by acid and assisted by microwaves irradiation under solvent free conditions. The final cyclocondensation with carbonyl compounds forming the tetrahydro derivatives was done under mild conditions, in which stereochemical induction was carried out on the building of this skeleton, and stereochemistry assignments corroborated by theoretical calculations.

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Ring-chain tautomerism in 2-substituted 1,2,3,4-tetrahydroquinazolines A 1H, 13C and 15N NMR study

Cited by 48 publications

References 24 publications

Syntheses, Structures, and Biological Activity of Ni^II, Pd^II, and Pt^II Complexes with New Tetradentate Benzamidine Ligands

Syntheses, Structures, and Biological Activity of Ni^II, Pd^II, and Pt^II Complexes with New Tetradentate Benzamidine Ligands

Structural variety of zinc and copper complexes based on a 2,3-disubstituted 1,2,3,4-tetrahydroquinazoline ligand

Easy synthesis of new series of pteridine analogs: di- and tetra-hydropyrimido[4,5-d]pyrimidines via 5-pyrimidinecarbaldehydes

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Ring-chain tautomerism in 2-substituted 1,2,3,4-tetrahydroquinazolines A 1H, 13C and 15N NMR study

Cited by 48 publications

References 24 publications

Syntheses, Structures, and Biological Activity of NiII, PdII, and PtII Complexes with New Tetradentate Benzamidine Ligands

Syntheses, Structures, and Biological Activity of NiII, PdII, and PtII Complexes with New Tetradentate Benzamidine Ligands

Structural variety of zinc and copper complexes based on a 2,3-disubstituted 1,2,3,4-tetrahydroquinazoline ligand

Easy synthesis of new series of pteridine analogs: di- and tetra-hydropyrimido[4,5-d]pyrimidines via 5-pyrimidinecarbaldehydes

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Resources

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Syntheses, Structures, and Biological Activity of Ni^II, Pd^II, and Pt^II Complexes with New Tetradentate Benzamidine Ligands

Syntheses, Structures, and Biological Activity of Ni^II, Pd^II, and Pt^II Complexes with New Tetradentate Benzamidine Ligands