A theoretical analysis of the conformational space of tris(2-methylbenzimidazol-1-yl)methane

Alkorta, Ibón; Elguero, José

doi:10.1016/j.tetasy.2010.02.023

Cited by 9 publications

(4 citation statements)

References 52 publications

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“…Due to the tetrahedral nature of the spiro atom, the two rings are not coplanar but twisted almost perpendicularly to each other. These particular arrangements, which are carriers of strong steric constraints, make the construction of all-carbon quaternary centers a formidable challenge for synthetic organic chemists and may markedly characterize the biological activity of synthetic and natural substances that include them in their structure. − …”

Section: Introductionmentioning

confidence: 99%

The Anancomeric Character of the Pharmacophore 1,3,4-Thiadiazoline Framework in Chiral Spiro-Cyclohexyl Derivatives: Effects on Stereochemistry and Spiro-Junction Lability. Thermodynamic Aspects

et al. 2015

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Three new and easily accessible chiral compounds, containing the pharmacophore 1,3,4-thiadiazoline nucleus joined by a spiro center to a monoalkyl (methyl or t-butyl) substituted cyclohexyl fragment, have been synthesized and fully characterized from the structural and stereochemical point of view. The formation of a spiro-cyclohexyl-thiadiazoline system (sCT) offered the rare opportunity to generate at room temperature both anancomeric structures, displaying alkyl groups bound to the cyclohexyl ring in equatorial position, and other quite stable stereoisomers in which the same alkyl moieties are, instead, inserted in axial position, even for the extreme case represented by the really bulky t-butyl group. DFT calculations led to a clear rationalization of such stereochemical behaviors, pointing out that in all cases they arise from the unexpected strong anancomeric character possessed by the sCT framework in its 4-acetyl substituted version. In consideration of the large number of substances in which the 1,3,4-thiadiazoline heterocycle has been found as the active pharmacophore, the results discussed in this work may provide solid bases to allow a rational design of new chiral bioactive spiro-thiadiazolines characterized by well-defined stereochemical structures and single anancomeric geometries.

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Section: Introductionmentioning

confidence: 99%

The Anancomeric Character of the Pharmacophore 1,3,4-Thiadiazoline Framework in Chiral Spiro-Cyclohexyl Derivatives: Effects on Stereochemistry and Spiro-Junction Lability. Thermodynamic Aspects

et al. 2015

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“…The racemisation barrier and 1 H and 13 C chemical shieldings for tris(2-methylbenzimidazol-1-yl)methane were studied. 8 The through-space NMR shieldings (TSNMRS) of benzenoid and quinonoid structures (hydroquinone/ p-benzoquinone, p-phenylendiamine/p-phenylendiimine, pentacene and N-containing heteropentacenes) were calculated by the GIAO perturbation method employing the nucleus-independent chemical shift concept and visualised as isochemical shielding surfaces. 9 The relative magnitudes of the chemical shift differences in the two diastereomers of menthyl esters of chiral derivatising agents and a-methoxy-a-trifluoromethyl-1-naphthylacetyl analogs were compared and long-range shielding effects in the 1 H NMR Spectra discussed.…”

Section: Shielding Of Particular Nuclear Speciesmentioning

confidence: 99%

Applications of nuclear shielding

Kuroki¹,

Matsukawa²,

Yasunaga³

2011

Nuclear Magnetic Resonance

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“…For instance, structure types 335 duu and 355 duu should be read 3Me- d , 3Me- u , 5Me- u and 3Me- d , 5Me- u , 5Me- u . We have used this nomenclature in previous papers [4,5,6].…”

Section: Introductionmentioning

confidence: 99%

An Example of Polynomial Expansion: The Reaction of 3(5)-Methyl-1H-Pyrazole with Chloroform and Characterization of the Four Isomers

Silva

Claramunt

et al. 2019

Molecules

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The reaction in phase-transfer catalyzed conditions of 3(5)-methyl-1H-pyrazole with chloroform affords four isomers 333, 335, 355 and 555 in proportions corresponding to the polynomial expansion (a + b)3, with a = 0.6 and b = 0.4, a and b being 3-methyl and 5-methyl proportions. The up (u) and down (d) conformation of the pyrazolyl rings with regard to the Csp3–H atom was established by X-ray crystallography and by 1H-, 13C- and 15N-NMR in solution combined with gauge-including atomic orbitals (GIAO)/B3LYP/6-311++G(d,p) calculations. A comparison with other X-ray structures of tris-pyrazolylmethanes was carried out.

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A theoretical analysis of the conformational space of tris(2-methylbenzimidazol-1-yl)methane

Cited by 9 publications

References 52 publications

The Anancomeric Character of the Pharmacophore 1,3,4-Thiadiazoline Framework in Chiral Spiro-Cyclohexyl Derivatives: Effects on Stereochemistry and Spiro-Junction Lability. Thermodynamic Aspects

The Anancomeric Character of the Pharmacophore 1,3,4-Thiadiazoline Framework in Chiral Spiro-Cyclohexyl Derivatives: Effects on Stereochemistry and Spiro-Junction Lability. Thermodynamic Aspects

Applications of nuclear shielding

An Example of Polynomial Expansion: The Reaction of 3(5)-Methyl-1H-Pyrazole with Chloroform and Characterization of the Four Isomers

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