Synthesis of Pyrrole‐Fused Corannulenes: 1,3‐Dipolar Cycloaddition of Azomethine Ylides to Corannulene

Abstract

In the long history of corannulene chemistry, the 1,3-dipolar cycloaddition to corannulene is unprecedented. Reported herein is the 1,3-dipolar cycloaddition of a polycyclic aromatic azomethine ylide to corannulene, a reaction which occurs exclusively at the rim bond of corannulene, from the convex side in an exo fashion. The cycloadducts were successfully converted, by successive oxidative dehydrogenation, into pyrrole-fused corannulenes, which exhibited pronounced solvatofluorochromism.

A Hybrid of Corannulene and Azacorannulene: Synthesis of a Highly Curved Nitrogen‐Containing Buckybowl

“…Communications emission spectra of 8a are shifted to longer wavelength relative to those of azapentabenzocorannulene 7a [16] and pyrrole-fused corannulene 12 a (Figure 3). [21] These results show that the p conjugation is extended effectively to narrow the HOMO-LUMO gap of 8a compared to that in 7a and 12 a.S ubsequently,w ec arried out cyclic voltammetry (CV) measurements to experimentally investigate the electronic properties of 8a ( Figure S27). Upon oxidation, ar eversible one-electron oxidation wave (E 1/2 ox1 = 0.31 Vv s. Fc/Fc + )a nd an irreversible oxidation wave (E 1/2 ox2 % 0.90 Vv s. Fc/Fc + ) were observed.…”

“…This 1,3-dipolar cycloaddition to 1 has recently been developed in our group. [21] Thus,pyrrole-fused corannulene 11 was obtained in 22 %y ield. Subsequently, 11 was subjected to apalladium-catalyzed intramolecular cyclization, which afforded 8a in 46 %y ield (Scheme 1).…”

Helical Ullazine‐Quinoxaline‐Based Polycyclic Aromatic Hydrocarbons

“…Furthermore, Ito et al extended the selection of dipolarophile examples with pure carbon dipolarophiles without electron-withdrawing groups at highert emperature. [8,9] Recently, we demonstrated the transformation of symmetric acene-quinone (2,s ee Figure1)i nto fully conjugated benzoisoindolebased planar N-PAHs by nucleophilic addition to the para-quinone core and following dehydroxylative reduction. [10] However,t he addition of PAMY to ortho-quinones has so far not been explored although it would allow lateral extension of the asymmetricg erminal ketonef unctionalities through further condensation reactions to form N-PAHs with additional quinoxalineunits ( Figure 1).…”

A Hybrid of Corannulene and Azacorannulene: Synthesis of a Highly Curved Nitrogen‐Containing Buckybowl

“…Therefore, we started the synthesis of 8 a from corannulene ( 1 ) through a 1,3‐dipolar cycloaddition of polycyclic aromatic azomethine ylide 10 , which was generated in situ from the corresponding iminium chloride ( 9 ), to 1 (for details, see the Supporting Information). This 1,3‐dipolar cycloaddition to 1 has recently been developed in our group . Thus, pyrrole‐fused corannulene 11 was obtained in 22 % yield.…”