Stereoisomeric Relationships of Groups in Molecules

Mislow, Kurt; Raban, Morton

doi:10.1002/9780470147108.ch1

Cited by 254 publications

(45 citation statements)

References 28 publications

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“…In these lowbarrier or vanishing-barrier cases, a neighboring permanently chiral object can break the symmetry between the transient enantiomers or enantiotopic faces of the molecule. [152] This phenomenon is called chirality induction, because the permanently chiral object induces chirality in the transiently chiral or prochiral molecule, thus leading to an energy difference between the two directions of approach. Figure 12 also illustrates the third case of a fully achiral molecule (H 2 O), which does not lead to an energy difference.…”

Section: Chirality Inductionmentioning

confidence: 99%

Chirality Recognition between Neutral Molecules in the Gas Phase

2008

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Noncovalent interactions are particularly intriguing when they involve chiral molecules, because the interactions change in a subtle way upon replacing one of the partners by its mirror image. The resulting phenomena involving chirality recognition are relevant in the biosphere, in organic synthesis, and in polymer design. They may be classified according to the permanent or transient chirality of the interacting partners, leading to chirality discrimination, chirality induction, and chirality synchronization processes. For small molecules, high-level quantum chemical calculations for such processes are feasible. To provide reliable connections between theory and experiment, such phenomena are best studied in vacuum isolation at low temperature, using rotational, vibrational, electronic, and photoionization spectroscopy. We review these techniques and the results which have become available in recent years, with special emphasis on dimers of permanently chiral molecules and on the influence of conformational flexibility. Analogies between the microscopic mechanisms and macroscopic phenomena and between intra- and intermolecular cases are drawn.

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Section: Chirality Inductionmentioning

confidence: 99%

Chirality Recognition between Neutral Molecules in the Gas Phase

2008

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“…Aided by Mislow's geometric considerations [28] and in pursuit of our previous studies, [20 -22] we arrive at an entirely different rationalisation in which neither the M 3 (tpt)-triangle tilt nor a counterion-induced enantiodifferentiation plays a role.…”

Section: Resultsmentioning

confidence: 91%

“…We conclude that the NMR spectra of 2 do not reflect different properties of pairs of protons which are enantiotopic by external comparison, [28] i.e. which reside in enantiomeric cations.…”

Section: Resultsmentioning

confidence: 92%

“…The NMR spectra contain no features which might support the assumptions that the propeller arrangement is induced either by the tpt tilt or by the6c anions. The NMR phenomena are fully accounted for by pairs of protons that are enantiotopic by internal comparison, [28] i.e. which reside pairwise within only one type of cationic molecules which are achiral in the sense that facile intramolecular motions leading to chiral conformations are not regarded as a source of chirality.…”

Section: Resultsmentioning

confidence: 99%

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The impact of ion pair association upon the ¹H NMR spectra of cationic complexes akin to Grubbs catalysts

Schiemenz

2010

Magnetic Reson in Chemistry

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A reconsideration of the (1)H NMR spectra of cationic transition metal complexes exhibiting the features of cyclophanes on the basis of Mislow's classification of topic groups arrives at the conclusion that the spectral changes triggered by chiral counterions reflect an intracationic diastereotopication of enantiotopic protons rather than the existence of pairs of long-lived diastereomeric ion pairs.

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“…(Formally, in the context of PIM, the above terms 'identical' or 'equivalent' and 'nonidentical' or 'nonequivalent' would be termed 'homotopic' and 'heterotopic' respectively, following the original suggestion of Mislow and Raban.) 4 The above discussion indicates that the interaction of a prostereogenic molecule with a chiral environment leads to unique stereochemical consequences. These, of course, derive from the definition of PIM itself.…”

Section: Introductionmentioning

confidence: 97%

Prostereoisomerism and biological activity: possible implications for drug design

Chandrasekhar¹

2016

Turk J Chem

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Prostereoisomerism (PIM), representing a subgroup within the achiral class of molecules, is manifested in a chiral environment. Although this is regardless of the orientation of the prostereoisomeric (PIC) molecule, PIM is manifested most emphatically in relation to a chiral surface ('two-dimensional chirality'). Then PIM is tantamount to 'de facto chirality' as attachment of the PIC molecule to the surface leads to diastereomeric possibilities (cf. Ogston's hypothesis). Furthermore, the formation of host-guest complexes requires a steric complementarity between the component molecules. The fact that the weak dispersive forces involved therein require an optimum distance implies a 'snugness of fit' criterion. This further implies that a chiral host prefers a chiral guest molecule, and a chiral surface prefers a PIC molecule as substrate. These indicate a general stereochemical criterion for host-guest complexation that is particularly relevant to the case of biological receptors. Indeed, a survey of several known achiral drug molecules indicates that they generally possess at least one PIC moiety, lending credence to the above arguments. Thus, it would appear that PIM represents a maximum level of molecular symmetry for biological activity to be manifested efficiently.

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Stereoisomeric Relationships of Groups in Molecules

Cited by 254 publications

References 28 publications

Chirality Recognition between Neutral Molecules in the Gas Phase

Chirality Recognition between Neutral Molecules in the Gas Phase

The impact of ion pair association upon the ¹H NMR spectra of cationic complexes akin to Grubbs catalysts

Prostereoisomerism and biological activity: possible implications for drug design

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Stereoisomeric Relationships of Groups in Molecules

Cited by 254 publications

References 28 publications

Chirality Recognition between Neutral Molecules in the Gas Phase

Chirality Recognition between Neutral Molecules in the Gas Phase

The impact of ion pair association upon the 1H NMR spectra of cationic complexes akin to Grubbs catalysts

Prostereoisomerism and biological activity: possible implications for drug design

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The impact of ion pair association upon the ¹H NMR spectra of cationic complexes akin to Grubbs catalysts