Structure, conformation, stereodynamics, dimer formation, and absolute configuration of axially chiral atropisomers of hindered biphenyl carbinols

D Casarini, L Lunazzi, M Mancinelli…

Index: Casarini, Daniele; Lunazzi, Lodovico; Mancinelli, Michele; Mazzanti, Andrea; Rosini, Carlo Journal of Organic Chemistry, 2007 , vol. 72, # 20 p. 7667 - 7676

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Citation Number: 32

Abstract

NMR spectra of biphenyl derivatives bearing a single CR2OH substituent in the ortho position indicate that they exist as sp (more stable) and ap (less stable) conformers, due to the restricted rotation about the Ar-CR2OH bond. When R= Et (compound 2) the corresponding rotation barrier was determined (7.5 kcal mol-1) by line shape simulation of the low-temperature NMR spectra. Introduction of the prochiral i-Pr group in the position 3' ...