Acetylene diethers: a logical entry to oxocarbons

Serratosa, Francesc

doi:10.1021/ar00089a004

Cited by 68 publications

(53 citation statements)

References 32 publications

(3 reference statements)

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“…As the HOMO-LUMO transition involves a change in the value of L, it is always rotationally forbidden. Thus, the HOMO-LUMO transition may contribute a diatropic ring current for the neutral C 3 (CH 2 ) 3 (1 a), but neither diatropic nor paraA C H T U N G T R E N N U N G tropic currents for C N (CH 2 ) N with N > 3 (2 a-4 a). This leaves only the possibility of local circulations along/within the "arms" of the molecules, which are not addressed in pure Hückel theory (in which all current flow is along paths defined by the existence of s bonds), though if any such circulations exist they would appear in the full ab initio maps, or in maps from the pseudo-p method, [18] or any other method that takes account of the spatial extent of the p basis functions.…”

Section: àmentioning

confidence: 99%

“…Only the [3]radialene(C 3 (CH 2 ) 3 2À (1 b)), deltate (C 3 O 3 2À (5 b)) and thiodeltate (C 3 S 3 2À (9 b)) ions show a weak diatropic circulation in the central ring. These have respective values of 0.014, 0.018 and 0.019 a.u., for j CC , the in-plane component of the contribution of all electrons in orbitals of p symmetry to induced current per unit of applied field at a point 1a 0 above the geometric centre of one of the edges of the CCC triangle; the corresponding value for the total p current in benzene (the maximum in the 1a 0 plotting plane) is 0.080 a.u.…”

Section: àmentioning

confidence: 99%

“…Oxocarbon dianions (5 b-8 b, Figure 1) have an extensive chemistry, [1][2][3][4] with its beginnings in the early nineteenth century, and they were long considered, following the proposal of West et al, [5][6][7][8][9][10][11] to form an aromatic series. More recent work has questioned the aromaticity of the larger di-A C H T U N G T R E N N U N G anions [12][13][14] and of their thio analogues.…”

Section: Introductionmentioning

confidence: 99%

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On the Lack of Ring‐Current Aromaticity of (Heteroatom) [N]Radialenes and their Dianions

Domene

Fowler

Jenneskens

et al. 2006

Chemistry A European J

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Current‐density maps, calculated at the ab initio RHF//6–31G**/CTOCD‐DZ level, show no significant π ring current in planar equilateral geometries of neutral and dianionic [N]radialenes, oxocarbons and thiocarbons CNYNq− (Y=CH2, O, S; N=4, 5, 6; q=0 (1 a–12 a), 2 (1 b–12 b)). Only the N=3 deltate dianions C3Y32− (Y=CH2, O, S (1 b, 5 b and 9 b)) have discernible π ring current, and then with at most 20–25 % of the strength of the standard benzene current. On the magnetic criterion, lack of current is definitive evidence against aromaticity. Pictorial molecular‐orbital analysis within the ipsocentric approach shows this to be an inevitable consequence of the nodal structure of the π and π* orbitals of [N]radialene‐like systems. On grounds of angular‐momentum symmetry, spatial distribution, or both, the HOMO–LUMO excitation does not contribute a significant central diamagnetic ring current.

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Section: àmentioning

confidence: 99%

Section: àmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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On the Lack of Ring‐Current Aromaticity of (Heteroatom) [N]Radialenes and their Dianions

Domene

Fowler

Jenneskens

et al. 2006

Chemistry A European J

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“…The resultant substituted semisquarates can mimic the unstable equivalent and therefore obtain different electronic properties. These changes in property may result in new interactions with the active site in proteins and other biomolecules [110]. The semisquarates of cyanides and amino derivatives should be relatively stable in the ring form.…”

Section: Figure 22 Tetrazole -Semisquarate Interchangementioning

confidence: 99%

Squaryl Molecular Metaphors – Application to Rational Drug Design and Imaging Agents

Kitson¹

2017

J Diagn Imaging Ther

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Molecular Metaphors is the application of squaryl building blocks towards creative functional group chemistry to produce lead compounds and imaging agents. This strategy is applied to rational drug design and to various imaging agents that would normally contain conventional functional group chemistry. These, include carboxylic acids, α-amino acids, peptide bonds and phosphonates. Moreover, the squaryl metaphor is a precursor to complex organic molecules involving functional group interchange (FGI) and rearrangements. This article discusses the application of these metaphors in the area of neurochemistry, especially NMDA receptors. An important area of drug design is the inhibition of angiotensin II enzyme by the use of losartan. This commercial drug contains a tetrazole moiety that can be modified using the squaryl group to give a semisquarate derivative. These concepts can extend to the semisquarate of ibuprofen. Moreover, a discussion on peptidomimetics regarding the substitution of the peptide bond for squaramide allows for a change in the biological properties due to modification at the peptide bond. Furthermore, the topic on how squaryl metaphors can be exploited primarily by the central 1,3-hydroxyamide sequence to the generation of a novel class of HIV protease inhibitors. Also, squaryl metaphors can be used to develop potential inhibitors of glutathione and novel anti-migraine drugs. The discussion continues on the design of anticancer drugs: in particular, a novel class of metalloproteases, including phosphonates for semisquaramides, leading to squaryl nucleosides. This review concludes with the application of squaryl metaphors in the design of positron emission tomography (PET) and magnetic resonance imaging (MRI) agents towards theranostics. describe the ability of individual functional chemical groups to mimic other moieties [2,3]. KeywordsErlenmeyer rationalised these concepts and categorised isosteres into atoms, ions and molecules based on the valence level of electrons [4]. A further understanding by Friedman led to the term bioisosterism to include all atoms and molecules that fit the broadest definition of isosteres [5]. This approach was independent of whether the drug was an agonist or an antagonist towards biological activity.Moreover, Thornber applied the term bioisosterism to include subunits, groups or molecules that possess physicochemical properties of similar biological effects [6]. Finally, in 1991 Burger widened the definition of bioisosteres to include compounds or groups that possess similar molecular shapes and volumes independent of agonists or antagonists [7]. REVIEW ARTICLE Squaryl KitsonThese bioisosteres would require approximately the same distribution of electrons and give a high probability of generating comparable physical properties such as hydrophobicity [8]. Currently, bioisosterism is one of the most useful tools to the medicinal chemist in rational drug design and in particular regarding the carboxylic acid bioisosteres [9]. The carboxylic acid functional ...

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“…Oxidation of THQ can lead to diverse aromatic oxocarbon dianions such as rhodizonate or croconate [18,19]. Rhodizonate is red and possesses a notable chelating capacity.…”

Section: The Tetrahydroxy-14-quinone/tc(vii) Systemmentioning

confidence: 99%

Study of the Interaction Between Technetium and Tetrahydroxy-1,4-Quinone

Gráses

Far

1986

Radiochimica Acta

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Technetium/Technetium in vegetation/Tetrahydroxy-1,4-quinone/Technetium complexet SummaryInteractions between technetium and tetrahydroxy-1,4-quinone (THQ) in presence and absence of a reducing agent (SnCl,) were studied. It was found that in absence of the reducing agent THQ was oxidized by Tc(VII) and complex formation took place between reduced technetium and the oxidized reagent. In the presence of Sn(II) ions, reduction of THQ was observed, technetium acting as a catalyst. As a consequence of these studies a catalytic method for technetium determination was developed and applied to the determination of the element in vegetation.

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Acetylene diethers: a logical entry to oxocarbons

Cited by 68 publications

References 32 publications

On the Lack of Ring‐Current Aromaticity of (Heteroatom) [N]Radialenes and their Dianions

On the Lack of Ring‐Current Aromaticity of (Heteroatom) [N]Radialenes and their Dianions

Squaryl Molecular Metaphors – Application to Rational Drug Design and Imaging Agents

Study of the Interaction Between Technetium and Tetrahydroxy-1,4-Quinone

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