Correlated rotation in complex triarylmethanes. II. The 16- and 8-isomer systems and residual diastereotopicity

Paolo Finocchiaro, Devens Gust, Kurt Mislow

Research output: Contribution to journalArticle

39 Citations (Scopus)

Abstract

The dynamic stereochemistry of two complex triarylmethane systems has been studied. In one of these, the molecule has three different aryl groups, two of which lack local C2 axes coincident with the bonds to the central carbon atom. Although all conformers of this methane are rapidly interconverted at ambient temperatures by two-ring flip pathways, and in spite of the fact that there are no restrictions upon the individual torsional angles of the aryl groups, this compound still exhibits residual diastereotopicity, i.e., the groups in the ortho positions of the ring with a C2 axis still give rise to separate resonances in the 1H nmr spectrum. Isomerization, presumably by the one-ring flip mechanism, is necessary to cause coalescence of these signals. The barrier for this process is greater than 26 kcal/mol. Residual diastereotopicity is also observed in methanes with three different aryl groups, only one of which lacks a local C2 axis, but in this case all conformers and all diastereomeric environments are averaged by two-ring flips.

Original languageEnglish (US)
Pages (from-to)3205-3213
Number of pages9
JournalJournal of the American Chemical Society
Volume96
Issue number10
StatePublished - 1974
Externally publishedYes

Fingerprint

Methane
Isomers
Stereochemistry
Isomerization
Coalescence
Large scale systems
Carbon
Atoms
Molecules
Temperature

ASJC Scopus subject areas

  • Chemistry(all)

Cite this

Correlated rotation in complex triarylmethanes. II. The 16- and 8-isomer systems and residual diastereotopicity. / Finocchiaro, Paolo; Gust, Devens; Mislow, Kurt.

In: Journal of the American Chemical Society, Vol. 96, No. 10, 1974, p. 3205-3213.

Research output: Contribution to journalArticle

@article{0b672f5a78644339a7c253ea3c7ef540,
title = "Correlated rotation in complex triarylmethanes. II. The 16- and 8-isomer systems and residual diastereotopicity",
abstract = "The dynamic stereochemistry of two complex triarylmethane systems has been studied. In one of these, the molecule has three different aryl groups, two of which lack local C2 axes coincident with the bonds to the central carbon atom. Although all conformers of this methane are rapidly interconverted at ambient temperatures by two-ring flip pathways, and in spite of the fact that there are no restrictions upon the individual torsional angles of the aryl groups, this compound still exhibits residual diastereotopicity, i.e., the groups in the ortho positions of the ring with a C2 axis still give rise to separate resonances in the 1H nmr spectrum. Isomerization, presumably by the one-ring flip mechanism, is necessary to cause coalescence of these signals. The barrier for this process is greater than 26 kcal/mol. Residual diastereotopicity is also observed in methanes with three different aryl groups, only one of which lacks a local C2 axis, but in this case all conformers and all diastereomeric environments are averaged by two-ring flips.",
author = "Paolo Finocchiaro and Devens Gust and Kurt Mislow",
year = "1974",
language = "English (US)",
volume = "96",
pages = "3205--3213",
journal = "Journal of the American Chemical Society",
issn = "0002-7863",
publisher = "American Chemical Society",
number = "10",

}

TY - JOUR

T1 - Correlated rotation in complex triarylmethanes. II. The 16- and 8-isomer systems and residual diastereotopicity

AU - Finocchiaro, Paolo

AU - Gust, Devens

AU - Mislow, Kurt

PY - 1974

Y1 - 1974

N2 - The dynamic stereochemistry of two complex triarylmethane systems has been studied. In one of these, the molecule has three different aryl groups, two of which lack local C2 axes coincident with the bonds to the central carbon atom. Although all conformers of this methane are rapidly interconverted at ambient temperatures by two-ring flip pathways, and in spite of the fact that there are no restrictions upon the individual torsional angles of the aryl groups, this compound still exhibits residual diastereotopicity, i.e., the groups in the ortho positions of the ring with a C2 axis still give rise to separate resonances in the 1H nmr spectrum. Isomerization, presumably by the one-ring flip mechanism, is necessary to cause coalescence of these signals. The barrier for this process is greater than 26 kcal/mol. Residual diastereotopicity is also observed in methanes with three different aryl groups, only one of which lacks a local C2 axis, but in this case all conformers and all diastereomeric environments are averaged by two-ring flips.

AB - The dynamic stereochemistry of two complex triarylmethane systems has been studied. In one of these, the molecule has three different aryl groups, two of which lack local C2 axes coincident with the bonds to the central carbon atom. Although all conformers of this methane are rapidly interconverted at ambient temperatures by two-ring flip pathways, and in spite of the fact that there are no restrictions upon the individual torsional angles of the aryl groups, this compound still exhibits residual diastereotopicity, i.e., the groups in the ortho positions of the ring with a C2 axis still give rise to separate resonances in the 1H nmr spectrum. Isomerization, presumably by the one-ring flip mechanism, is necessary to cause coalescence of these signals. The barrier for this process is greater than 26 kcal/mol. Residual diastereotopicity is also observed in methanes with three different aryl groups, only one of which lacks a local C2 axis, but in this case all conformers and all diastereomeric environments are averaged by two-ring flips.

UR - http://www.scopus.com/inward/record.url?scp=0001067171&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0001067171&partnerID=8YFLogxK

M3 - Article

VL - 96

SP - 3205

EP - 3213

JO - Journal of the American Chemical Society

JF - Journal of the American Chemical Society

SN - 0002-7863

IS - 10

ER -