The polar bond–polarizable bond interaction in 1-X,2-methoxy naphthalenes. An experimental and theoretical study

Contreras, Rubén H.; Taurian, Oscar E.; Fernández, Federico; Peralta, Juan E.

doi:10.1016/s0022-2860(00)00642-6

Cited by 3 publications

(1 citation statement)

References 68 publications

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“…For the simple, vinyl enol ethers with substituents exercising little steric hinderance the s‐ cis conformation is preferred, whereas for the sterically more demanding isopropyl and tert ‐butyl vinyl enol ether the s‐ trans conformation was observed. For conformational studies in solution two NMR‐based approaches have been reported: the correlation of the 13 C‐NMR chemical shifts with the conformation [34–40] and different types of NOE‐experiments [41–45] . From the 13 C‐NMR results, only qualitative results can be deduced.…”

Section: Introductionmentioning

confidence: 99%

Conformations of 4‐tert‐Butyloxy‐, 4‐(Trimethylsilyl)oxy‐ and 4‐(Trimethylstannyl)oxy‐6‐methyl‐2H‐pyran‐2‐ones in the Crystalline State and in Solution

Neier

Baak

Jaun

et al. 2022

Helvetica Chimica Acta

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The conformational studies in solution and in the solid state of substituted 6‐methyl‐4‐hydroxy‐2‐pyrones indicated that the substituents on the 4‐hydroxy group clearly favored the s‐cis arrangement towards the formal double bond. Steady state kinetic NOE measurements of the tert‐butyl, trimethylsilyl and the trimethylstannyl derivatives showed a marked preference for this conformation in solution. The structures determined by X‐ray diffraction demonstrated the exclusive presence of the same conformation in the solid state. In these three derivatives, the pertinent dihedral angle deviates only slightly from the value for coplanarity with the formal double bond. The predictions of the τ‐bond model are in accordance with the observations. The X‐ray structure of the trimethylstannyl derivative reveals pentacoordinated tin with short contacts to the oxygens at the 2 and 4 position of neighboring molecules. The tin center plays both the role of a protecting group for the 4‐hydroxy moiety and of a Lewis acid towards the 2‐carbonyl oxygen. The X‐ray structure of the stannyl derivative shows unique features which can be compared to the extended transition state of aldol reactions.

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Section: Introductionmentioning

confidence: 99%

Conformations of 4‐tert‐Butyloxy‐, 4‐(Trimethylsilyl)oxy‐ and 4‐(Trimethylstannyl)oxy‐6‐methyl‐2H‐pyran‐2‐ones in the Crystalline State and in Solution

Neier

Baak

Jaun

et al. 2022

Helvetica Chimica Acta

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On the unusual²Jcoupling dependence onsyn/antiCHO conformation in 5‐X‐furan‐2‐carboxaldehydes

Pérez¹,

Suardíaz²,

Ortíz³

et al. 2008

Magnetic Reson in Chemistry

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A remarkable difference for (2)J(C(2)-H(f)) coupling constant in syn and anti conformers of 5-X-furan-2-carboxaldehydes (X = CH(3), Ph, NO(2), Br) and a rationalization of this difference are reported. On the basis of the current knowledge of the Fermi-contact term transmission, a rather unusual dual-coupling pathway in the syn conformer is presented. The additional coupling pathway resembles somewhat that of the J(H-H) in homoallylic couplings, which are transmitted by hyperconjugative interactions involving the pi(C=C) electronic system. The homoallylic coupling pathway can be labeled as sigma*(C-H) <-- pi(C=C) --> sigma*(C-H). In the present case, this additional coupling pathway, using an analogous notation, can be labeled as sigma*(C(2)-C(C)) <-- LP(1)(O(1))...LP(2)(O(C)) --> sigma*(C(C)-H(f)) (sigma*(C(2)-C(C))) where O(1) and O(C) stand for the ring and carbonyl O atoms, respectively. This additional coupling pathway is not activated in the anti conformers since both oxygen lone pairs do not overlap.

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13C NMR studies on the structure of 5H- and 6H-indolo-[2,3-b]quinolines and the related compounds

Kamieńska‐Trela

Kania

Bechcicka

et al. 2003

Journal of Molecular Structure

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The polar bond–polarizable bond interaction in 1-X,2-methoxy naphthalenes. An experimental and theoretical study

Cited by 3 publications

References 68 publications

Conformations of 4‐tert‐Butyloxy‐, 4‐(Trimethylsilyl)oxy‐ and 4‐(Trimethylstannyl)oxy‐6‐methyl‐2H‐pyran‐2‐ones in the Crystalline State and in Solution

Conformations of 4‐tert‐Butyloxy‐, 4‐(Trimethylsilyl)oxy‐ and 4‐(Trimethylstannyl)oxy‐6‐methyl‐2H‐pyran‐2‐ones in the Crystalline State and in Solution

On the unusual²Jcoupling dependence onsyn/antiCHO conformation in 5‐X‐furan‐2‐carboxaldehydes

13C NMR studies on the structure of 5H- and 6H-indolo-[2,3-b]quinolines and the related compounds

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The polar bond–polarizable bond interaction in 1-X,2-methoxy naphthalenes. An experimental and theoretical study

Cited by 3 publications

References 68 publications

Conformations of 4‐tert‐Butyloxy‐, 4‐(Trimethylsilyl)oxy‐ and 4‐(Trimethylstannyl)oxy‐6‐methyl‐2H‐pyran‐2‐ones in the Crystalline State and in Solution

Conformations of 4‐tert‐Butyloxy‐, 4‐(Trimethylsilyl)oxy‐ and 4‐(Trimethylstannyl)oxy‐6‐methyl‐2H‐pyran‐2‐ones in the Crystalline State and in Solution

On the unusual2Jcoupling dependence onsyn/antiCHO conformation in 5‐X‐furan‐2‐carboxaldehydes

13C NMR studies on the structure of 5H- and 6H-indolo-[2,3-b]quinolines and the related compounds

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On the unusual²Jcoupling dependence onsyn/antiCHO conformation in 5‐X‐furan‐2‐carboxaldehydes