Restricted Rotation Involving the Tetrahedral Carbon. XXXVI. Stereodynamics of 9-(2-MethylbenzyI)triptycene Derivatives
- 1 February 1981
- journal article
- research article
- Published by Oxford University Press (OUP) in Bulletin of the Chemical Society of Japan
- Vol. 54 (2) , 481-487
- https://doi.org/10.1246/bcsj.54.481
Abstract
DNMR study of a series of singly peri-substituted 9-(2-methylbenzyl)triptycene derivatives showed that the interconversion among the ap and ±sc rotamers with the o-methyl group pointing outside the triptycyl skeleton occurs by two consecutive gear motion steps by way of the unstable rotamers with the o-methyl group pointing inside. The+sc\ightleftharpoons−sc interconversion barriers (13.2—14.1 kcal/mol) are lower than the ap\ightleftharpoons±sc ones (17.7–20.8 kcal/ mol). The aryl group passes over a peri-hydrogen at the transition state of the former process and over the peri-substituent in the latter.Keywords
This publication has 13 references indexed in Scilit:
- Separation and identification of residual diastereomers in a maximally labeled triarylamineJournal of the American Chemical Society, 1980
- Restricted Rotation Involving the Tetrahedral Carbon. XXVI. Certainties and Uncertainties Involved in the Rates of Exchange among Three Sites as Obtained by Total Line Shape Analyses of 1H NMR Spectra: The Case of Methylene SignalsBulletin of the Chemical Society of Japan, 1979
- Restricted Rotation Involving the Tetrahedral Carbon. XXV. Barriers to Exchange between dl and meso Forms of 9-(Arylmethyl)triptycenesBulletin of the Chemical Society of Japan, 1979
- Stereochemical analysis of 1,1,2,2-tetraarylethanes. 2. Dynamic stereochemistry of selected tetraarylethanes and the use of residual stereoisomerism and residual stereotopism as a tool for differentiating among divers stereoisomerization pathwaysJournal of the American Chemical Society, 1976
- Stereochemical consequences of correlated rotation in molecular propellersAccounts of Chemical Research, 1976
- Restricted Rotation Involving the Tetrahedral Carbon. XIV. Conformational Equilibria and Attractive Interactions in Substituted 9-BenzyltriptycenesBulletin of the Chemical Society of Japan, 1975
- A convenient method for obtaining free energies of activation by the coalescence temperature of an unequal doubletThe Journal of Physical Chemistry, 1970
- The conformers of a nitrosamine and a carboxamide: Comparison of NMR line shape and equilibration methodsJournal of Molecular Spectroscopy, 1969
- Calibration of the methanol and glycol nuclear magnetic resonance thermometers with a static thermistor probeAnalytical Chemistry, 1968
- NMR Studies of the Rates of Inversion of o,o′-Bridged BiphenylsBulletin of the Chemical Society of Japan, 1964