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 - 1974/5/1
Y1 - 1974/5/1
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
U2 - 10.1021/ja00817a029
DO - 10.1021/ja00817a029
M3 - Article
AN - SCOPUS:0001067171
SN - 0002-7863
VL - 96
SP - 3205
EP - 3213
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
IS - 10
ER -