Dynamic NMR spectroscopy allowed, for the first time, the determination of the pi-barriers responsible for the enantiomerisation processes in derivatives bearing two aryl substituents bonded to a planar framework: this could be achieved in the case of 1,8-di-m-tolylbiphenylene (1) and 1,8-di-m-xylylbiphenylene (2). In derivative 1 the three possible conformers predicted by DFT computations (anti-in, syn and anti-out) were detected and, in addition, the steric barrier responsible for their interconversion could be measured. The barriers predicted by DFT calculations were found in satisfactory agreement with the experimental data.
L. Lunazzi, M. Mancinelli, A. Mazzanti (2007). Unprecedented Detection of the Enantiomerisation pi-Barriers due to Restricted Aryl Torsion: the Case of 1,8-Di-arylbiphenylenes. JOURNAL OF ORGANIC CHEMISTRY, 72, 10045-10050.
Unprecedented Detection of the Enantiomerisation pi-Barriers due to Restricted Aryl Torsion: the Case of 1,8-Di-arylbiphenylenes
LUNAZZI, LODOVICO;MANCINELLI, MICHELE;MAZZANTI, ANDREA
2007
Abstract
Dynamic NMR spectroscopy allowed, for the first time, the determination of the pi-barriers responsible for the enantiomerisation processes in derivatives bearing two aryl substituents bonded to a planar framework: this could be achieved in the case of 1,8-di-m-tolylbiphenylene (1) and 1,8-di-m-xylylbiphenylene (2). In derivative 1 the three possible conformers predicted by DFT computations (anti-in, syn and anti-out) were detected and, in addition, the steric barrier responsible for their interconversion could be measured. The barriers predicted by DFT calculations were found in satisfactory agreement with the experimental data.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
