Conjugative and steric factors affecting the conformational preference of some aromatic sulfides

Montaudo, Giorgio; Bottino, Francesco A.; Trivellone, E.

doi:10.1021/jo00968a042

Cited by 32 publications

(6 citation statements)

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“…It can be assumed that the presence of fairly large eight-CF3 groups in the tetrathiacalixarene 1 molecule should shift the equilibrium towards the least sterically hindered 1,3-alternate conformation similar to that determined by the X-ray method for the crystal state. A similar 1,3-alternate conformation was proposed earlier in the analysis of 1 H NMR spectra for solutions of tetrathiacalixarene without substituents in the internal macrocycle [14]. When four volume substituents (OC2H5) are introduced, the interconversion becomes difficult, and the equilibrium between all four possible conformations of tetrathiacalixarene according to NMR spectra is fixed [25].…”

Section: Resultssupporting

confidence: 62%

“…This widespread usage of thiacalixarenes is due to a fairly simple synthesis method based on the interaction of phenols with sulfur in the presence of NaOH [1,9]. Other synthesis methods are based on the aromatic nucleophilic substitution reactions in 1,3-dihalogenarenes or hetarenes [10][11][12][13][14][15]. Sodium sulphide [10] or sodium hydrosulphide [11], plus dithioresorcinol [12][13][14][15], can be used as the S-nucleophile in these reactions, which leads to the formation of thiacalixarenes containing several (n ≥ 3) identical aromatic (heteroaromatic) rings, as well as macrocycles with alternating acceptor and donor arenes.…”

Section: Introductionmentioning

confidence: 99%

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Synthesis of Polyfluorinated Thia- and Oxathiacalixarenes Based on Perfluoro-m-xylene

et al. 2021

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Perfluorinated tetrathiacalix[4]arene was obtained by heating perfluoro-m-xylene with thiourea or 2,5-difluoro-4,6-bis(trifluoromethyl)benzene-1,3-dithiol at 90 °C. Interaction of perfluoro-m-xylene with resorcinol or orcinol under mild conditions and subsequent heating of the mixture with 2,5-difluoro-4,6-bis(trifluoromethyl)benzene-1,3-dithiol leads to polyfluorinated dioxadithiacalix[4]arenes. Triphenyl and pentaphenyl ethers formed by the interaction of perfluoro-m-xylene with resorcinol under heating with thiourea gives polyfluorinated oxathiacalixarenes containing six and five aromatic nuclei, respectively.

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Section: Resultssupporting

confidence: 62%

Section: Introductionmentioning

confidence: 99%

Synthesis of Polyfluorinated Thia- and Oxathiacalixarenes Based on Perfluoro-m-xylene

et al. 2021

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“…For ortho-substituted diphenyl ethers and many other bridged diphenyls there is ample evidence to suggest that the twist, H-inside conformations are the most stable (7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26). Figure 3, which was prepared in the manner of Gust and Mislow (6), displays all eight possible twist conformers for a triply ortho-substituted diphenyl ether.…”

Section: Introductionmentioning

confidence: 99%

Conformations of Bridged Diphenyls. VI. Substituent Effects and Internal Rotation in Triply Ortho-substituted Diphenyl Ethers

Benjamins¹,

Dar²,

Chandler³

1974

Can. J. Chem.

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Experimental evidence is presented to support the hypothesis that, in triply ortho-substituted diphenyl ethers, conformer interconversion involves both rings. The free energy barrier, measured by p.m.r., is sensitive to substituent effects arising in the ring having only one ortho substituent. The exceptionally high barrier found when an ortho iodine is present is consistent with the existence of a substituent-inside intermediate occurring during conformer conversion.

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“…Although the shielding of H-6 in 2-nitrodiphenyl sulphide is explicable by the conjugative interactions suggested by Montaudo er a1. 28 for 2,4-dinitrodiphenyl sulphide, the shielding of H-6 by + M groups (OCH,, F, C1 and Br) may arise from factors other than conjugative interactions. Although several conformations with a wide range of torsional angles could be visualized for 2-substituted diphenyl sulphides, in order to understand the influence of X on the conformations, two extreme conformations, 4a and 4b, or conformations approximating to these (4a-like and 4b-like) can be considered.…”

Section: Effect Of Substituents On the Chemical Shift Of H-6 In Seriesmentioning

confidence: 99%

¹H and ¹³C NMR study of substituent effects in 2‐ and 3‐substituted diphenyl sulphides and sulphones and 4‐substituted 2′,6′‐dimethyldiphenyl sulphides

Perumal

Chandrasekaran

Vijayabaskar

et al. 1995

Magnetic Reson in Chemistry

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The proton and carbon NMR spectra of nine 2-substituted diphenyl sulphides (SZX), seven 3-substituted diphenyl sulphides (S-3-X), nine 2-substituted diphenyl sulphones (S02-2-X), nine hubstituted diphenyl sulphones (SO2-% X) and nine 4-substituted-2',6'-dimethyldiphenyl sulphides (Me2-S-4-X) were obtained. Correlations of the 'H and I3C chemical shifts were made with benzene substituent-induced chemical shifts (Lynch plots) and Hammett and dual-substituent parameters and the results were compared with those of 4-substituted diphenyl sulphides (S4-X) and sulphones (S02-4-X). The main conclusions are as follows: (i) the transmission of the substituent effects in substituted diphenyl sulphides decreases in the order S-4-X x S-2-X > Me,SQX > S-3-X; (ii) the inductive effects are transmitted to a larger extent than the resonance effects to the unsubstituted ring in Isubstituted diphenyl sulphides, while the reverse trend is observed in other substituted diphenyl sulphides; (iii) in 2-methoxy-, khloro-, 2-bromo-and 2-nitrodiphenyl sulphides, an increase in the size of the substituent causes an upfield shift for H d ascribable to the repulsion between the lone pairs of electrons on the sulphur and the substituent and its influence on the conformation; (iv) the diminished transmission of substituent effects to the remote rings in 4-substituted 2',6'-dimethyldiphenyl sulphides is probably due to the orthogonal orientation of the rings; and (v) the signal due to the H-6 of 2-substituted diphenyl sulphones suffers a downfield shift with an increase in the size of the substituent, this being ascribable to the increasing steric interaction between the 2-substituent and the sulphonyl oxygen and consequent changes in the conformation.

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Conjugative and steric factors affecting the conformational preference of some aromatic sulfides

Cited by 32 publications

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Synthesis of Polyfluorinated Thia- and Oxathiacalixarenes Based on Perfluoro-m-xylene

Synthesis of Polyfluorinated Thia- and Oxathiacalixarenes Based on Perfluoro-m-xylene

Conformations of Bridged Diphenyls. VI. Substituent Effects and Internal Rotation in Triply Ortho-substituted Diphenyl Ethers

¹H and ¹³C NMR study of substituent effects in 2‐ and 3‐substituted diphenyl sulphides and sulphones and 4‐substituted 2′,6′‐dimethyldiphenyl sulphides

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Conjugative and steric factors affecting the conformational preference of some aromatic sulfides

Cited by 32 publications

References 0 publications

Synthesis of Polyfluorinated Thia- and Oxathiacalixarenes Based on Perfluoro-m-xylene

Synthesis of Polyfluorinated Thia- and Oxathiacalixarenes Based on Perfluoro-m-xylene

Conformations of Bridged Diphenyls. VI. Substituent Effects and Internal Rotation in Triply Ortho-substituted Diphenyl Ethers

1H and 13C NMR study of substituent effects in 2‐ and 3‐substituted diphenyl sulphides and sulphones and 4‐substituted 2′,6′‐dimethyldiphenyl sulphides

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¹H and ¹³C NMR study of substituent effects in 2‐ and 3‐substituted diphenyl sulphides and sulphones and 4‐substituted 2′,6′‐dimethyldiphenyl sulphides