Fold-in Synthesis of an Ovalene Analogue Composed of Four Peripheral Amide Linkages

We report the successful synthesis of an ovalene tetraamide analogue based on the fold-in approach by 5-fold intramolecular direct arylation using a cyclic tetraamide precursor. Although the two carbon atoms of the precursor for the formation of the central C-C bond in the ovalene analogue were not halogenated, the planar structure of the resulting compound, along with five newly formed C-C bonds, was unambiguously determined by a combination of NMR spectroscopy, mass spectrometry, and X-ray crystallography. The ovalene tetraamide analogue exhibited intense absorption and fluorescence in the visible region, with a small Stokes shift (3 nm) and a distinct vibronic structure, indicating its structural rigidity.