Five‐Fold Symmetric Pentaindolo‐ and Pentakis(benzoindolo)Corannulenes: Unique Structural Dynamics Derived from the Combination of Helical and Bowl Inversions

Abstract

Peripherally p-extended corannulenes bearing quintuple azahelicene units, 10 and 11,w ere prepared and their dynamic behaviors were studied experimentally and theoretically.T he fused corannulenes were synthesized from sympentabromocorannulene in three steps.X -Rayd iffraction analysis for 10 displayed aconformer possessing aP(M) bowl chirality and aP PMPM (PMPMM) helical chirality,w hich was found to be the most stable conformer(s). Variabletemperature NMR measurements of 10 and 11 revealed that their structural isomers can be interconvertible in solution, depending on the steric congestion around the helical scaffolds. Automated search for conformers in the equilibrium and transition states by Artificial Force Induced Reaction (AFIR) method revealed their interconversion networks,i ncluding bowl-inversion and helical-inversion. This analysis indicated that the co-existing corannulene and azahelicene moieties influence the conformational dynamics,w hich leads to mitigation of the activation energy barriers for isomerization.