Efficient Visible-Light-Induced π-Extension of Perylene Tetraesters: An Investigation on Regioselectivity

The present study discloses a highly efficient visible-light-induced pi-extension of perylene tetraesters and discussion on the regioselectivity in the photocyclization. We initially found that pi-extension reaction of 3,4-dimethoxyphenyl perylene tetraester smoothly proceeded by only irradiating blue LED with a complete regioselectivity. Investigations of the photocyclization with various substrates revealed the relationship between the regioselectivity and electron-donating/withdrawing effects of the substituents on the aromatic groups. Moreover, theoretical investigation suggested the importance of bond alteration in the aromatic groups: cyclization proceeds preferentially at shorter C-C bonds with higher double bond characters. The findings will open new possibilities for the practical synthesis of custom-designed pi-extended perylene materials.