Control of inversion kinetics of bowl-shaped aromatic compounds

Bowl inversion property of bowl-shaped aromatic compounds, buckybowls, is reviewed in this chapter. Bowl inversion kinetics of many kinds of buckybowls have been extensively investigated including pristine buckybowls such as corannulene, sumanene, diindenochrysene, and extended buckybowls, substituted buckybowls, and heterobuckybowls. The magnitude of bowl inversion barrier was altered in very wide range depending on the kinds of buckybowl skeleton, the extension of bowl π-conjugation, the substituents, the heteroatoms, and the redox. Introduction of substituents changed the barriers in a few kcal/mol range and the correlation between the bowl inversion barriers and bowl depths was elucidated in corannulene and sumanene skeletons. Introduction of heteroatoms substantially changed the magnitude of inversion barrier without changing bowl sizes. Chiral buckybowls with stable bowl chirality were also achieved by realizing the high bowl inversion/racemization barrier by introduction of substituents or heteroatoms. Based on these extensive studies, bowl inversion kinetics can be controlled by these factors.