Chiral Sumanene, Triazasumanene, and Related Buckybowls

Syntheses of many buckybowls, bowl-shaped aromatic compounds, have been achieved from 1990s, including corannulene and sumanene. After the establishment of these preparative methods, the syntheses of functionalized buckybowls possessing additional factors became important for the elucidation of the fundamental properties of curved π-electron systems as well as the exploration of science and application. The syntheses of chiral sumanene derivatives and chiral triazasumanene have been recently achieved, which possess “chirality” and “heteroatom” as the additional factors. These chiral buckybowls and azabuckybowl were synthesized by employing the strategy to construct the conjugated bowl from nonconjugated bowl through the conventional synthetic method under mild conditions, amenable enough to control the chirality, the reactivity of heteroatom, and high strain of bowl structure. As one of intrinsic properties of curved π-electron system, the first stereoelectronic effect of bowl-shaped π-electron system controlling the conformation of substituted sumanene is also described.