Frontier molecular orbital effects control the hole-catalyzed racemization of atropisomeric biaryls. Issue 8 (4th January 2019)

• Record Type: Journal Article
• Authors: Tan, Jacqueline S. J.; Paton, Robert S.
• Is Part Of: Chemical science. Volume 10:Issue 8(2019)
• Page Start: 2285
• Page End: 2289
• Publication Date: 2019-01-04
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/c8sc05066j
• Languages: English
• ISSNs: 2041-6520

Abstract

Abstract : Biaryl atropisomerization is dramatically accelerated by the removal of an electron. The planar transition state is preferentially stabilized from depopulation of the highest occupied molecular orbital. Abstract : Atropisomeric biaryl systems are privileged architectures used in asymmetric synthesis and pharmaceutical structures. We report that by simply removing a single-electron, the resistance of biaryls towards racemization is reduced dramatically. Even though the steric properties are unaltered, biaryl oxidation changes atropisomerization into a two step mechanism with considerably smaller activation barriers than closed-shell biaryls. The effect is general for a series of biaryls and helicenes studied and results from the dependence of frontier molecular orbital energies on biaryl conformation.