π–π Stacking versus Steric Effects in Stereoselectivity Control: Highly Diastereoselective Synthesis of <i>syn</i>‐1,2‐Diarylpropylamines

Ruano, José Luis Garcı́a; Alemán, José V.; Alonso, Inés; Parra, Alejandro; Marcos, Vanesa; Aguirre, José M.

doi:10.1002/chem.200601893

Cited by 57 publications

(23 citation statements)

References 50 publications

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“…[10] In all these reactions, chelated structures, with the counterion (Li + ) joined to the benzylic carbon and stabilized by the sulfinyl oxygen, have been postulated to account for the stereoselectivity [Scheme 1, Eq. (1)].…”

Section: Introductionmentioning

confidence: 99%

Stereodivergent Quaternization of 2‐Alkyl‐2‐p‐tolylsulfinylacetonitriles: NMR Spectroscopic Evidence of Planar and Pyramidal Benzylic Carbanions

Ruano

Martín-Castro

Tato

et al. 2010

Chemistry A European J

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Enantiomerically enriched alpha,alpha-disubstituted phenylacetonitriles have been readily prepared by stereoselective quaternization of 2-alkyl-2-[2-(p-tolylsulfinyl)phenyl]acetonitriles with different alkylating electrophiles in the presence of bases. The use of potassium hexamethyldisilazane (KHMDS)/[18]crown-6 ether and NHMDS with alkyl halides afforded S,S(S) and R,S(S) diastereoisomers, respectively, in high enantiomeric purities, thus providing stereodivergent processes for synthesizing both isomers. The dependence of the stereochemical course of the reactions on the experimental conditions (mainly on the counterion) has been rationalized by assuming a planar or pyramidal structure for the benzylic carbanions. This hypothesis has been supported by NMR spectroscopic studies, which permit one to assign a chelated pyramidal structure to the sodium benzylic carbanions and an almost planar naked carbanionic structure to the potassium benzylic carbanions generated in the presence of [18]crown-6 ether.

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Section: Introductionmentioning

confidence: 99%

Stereodivergent Quaternization of 2‐Alkyl‐2‐p‐tolylsulfinylacetonitriles: NMR Spectroscopic Evidence of Planar and Pyramidal Benzylic Carbanions

Ruano

Martín-Castro

Tato

et al. 2010

Chemistry A European J

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“…Aryl-aryl interactions are key to understanding myriad chemical phenomena including stereoselective organic reactions [1-3], host-guest chemistry [4], and supramolecular self-assembly [5], yet are perhaps the least well-understood [6] among non-covalent interactions [7-10]. π-π interactions are also pivotal in numerous biochemical processes.…”

Section: Introductionmentioning

confidence: 99%

Origin of substituent effects in edge-to-face aryl–aryl interactions

Wheeler

Houk

2009

Molecular Physics

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Substituent effects in the edge-to-face configuration of the benzene dimer have been studied using modern density functional theory. An accurate interaction potential energy curve has been computed for the unsubstituted dimer using ab initio methods with large basis sets. The recommended binding energy for the edge-to-face benzene dimer is 2.31 kcal mol-1, estimated at the counterpoise-corrected CCSD(T)/aug-cc-pVTZ level of theory. For both edge-ring and face-ring-substituted dimers, interaction energies correlate with σm for the substituents, indicating that substituent effects can be understood qualitatively in terms of simple electrostatic effects, although in the latter case dispersion results in some scatter in the data. In contrast to prevailing models of substituent effects in benzene dimers, polarization of the π-system of the substituted ring does not induce substituent effects. For edge-ring-substituted dimers, substituent effects arise from differential electrostatic interactions between the hydrogens on the substituted ring and the π-cloud of the face ring and direct interactions of the substituents with the unsubstituted ring. For face-ring-substituted dimers, substituent effects arise from direct electrostatic and dispersion interactions of the substituents with the edge ring. Substituents with σm > 0.12 favor edge ring substitution while for σm < 0.12 substitution on the face ring is preferred.

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“…Arene–arene interactions have also been used to assemble supramolecular structures10–12 and to control the stereoselectivity of organic transformations 13. 14 Despite their importance, the factors that govern arene–arene interactions are not well understood, in contrast to other noncovalent interactions such as hydrogen bonding. There are two major reasons: the first is that arene–arene interactions are the sum of multiple forces of similar magnitude such as charge transfer, solvation, electrostatic interactions, and London dispersion forces 15.…”

Section: Introductionmentioning

confidence: 99%

A High‐Barrier Molecular Balance for Studying Face‐to‐Face Arene–Arene Interactions in the Solid State and in Solution

Chong

Carroll

Burns

et al. 2009

Chemistry A European J

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An atropisomeric molecular balance was developed to study face-to-face arene-arene interactions. The balance has a large central 1,4,5,8-naphthalene diimide surface that forms intramolecular arene-arene interactions with two pendent arms. The balance adopts distinct syn and anti isomers with varying numbers of intramolecular interactions. Thus, the strength of the arene-arene interaction could be quantitatively measured by NMR spectroscopy from the anti/syn ratios. The size of the arene arms was easily varied, which allowed examination of the relationship between arene size and strength of the interaction. A nonlinear size dependence was observed in solution with larger arene arms having a disproportionately stronger arene-arene interaction. The intramolecular arene-arene interactions were also characterized in the solid state by X-ray crystallography. These studies were facilitated by the kinetic stability of the syn and anti isomers at room temperature due to the high isomerization barrier (DeltaG=27.0 kcal mol(-1)). Thus, the anti isomer could be selectively isolated and crystallized in its folded conformation. The X-ray structures confirmed that the anti isomers formed two strong intramolecular arene-arene interactions with face-to-face geometries. The solid-state structure analysis also reveals that the rigid framework may contribute to the observed nonlinear size trend. The acetate linker is slightly too long, which selectively destabilizes the balances with smaller arene arms. The larger arene arms are able to compensate for the longer linker and form effective intramolecular arene-arene interactions.

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π–π Stacking versus Steric Effects in Stereoselectivity Control: Highly Diastereoselective Synthesis of syn‐1,2‐Diarylpropylamines

Cited by 57 publications

References 50 publications

Stereodivergent Quaternization of 2‐Alkyl‐2‐p‐tolylsulfinylacetonitriles: NMR Spectroscopic Evidence of Planar and Pyramidal Benzylic Carbanions

Stereodivergent Quaternization of 2‐Alkyl‐2‐p‐tolylsulfinylacetonitriles: NMR Spectroscopic Evidence of Planar and Pyramidal Benzylic Carbanions

Origin of substituent effects in edge-to-face aryl–aryl interactions

A High‐Barrier Molecular Balance for Studying Face‐to‐Face Arene–Arene Interactions in the Solid State and in Solution

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