Chiral Atropisomeric Indenocorannulene Bowls: Critique of the Cahn-Ingold-Prelog Conception of Molecular Chirality

摘要

Chiral corannulenes abound, but suffer generally from configurational lability associated with bowl-to-bowl inversion,([1]) thus obviating questions of stereogenicity and stereoelement construction.([2]) In contrast, peri-annulated corannulenes show greatly increased barriers for bowl-to-bowl inversion; specifically indenocorannulenes invert on a time scale too slow to observe by normal NMR methods and raise the possibility of creating chiral atropisomeric bowl-shaped aromatics.([3]) Two methods for preparing indenocorannulene from simple 2-haloarylcorannulenes-silyl cation C-F activation,([4]) and Pd-mediated C-Cl activation([5])-enable the synthesis of an array of such chiral atropisomeric indeno-corannulenes.([6]) Resolution of the enantiomers by high-performance liquid chromatography over chiral support phases motivates the study of chiroptical properties, the assignment of absolute "Cartesian" configuration, and the assessment of configurational stability.([7]) These studies bring into question any systematic assignment of nontrivial stereoelements (i.e. not the molecule in its entirety) and refute any assertion of congruence between "Cahn-Ingold-Prelog elements" and the physical or "Cartesian" basis of chirality.