title: Synthesis of biladienone and bilatrienone by coupled oxidation of tetraarylporphyrins.
abstract: Tetraarylbiladien-ab-ones bearing various substituents (R) in the para position of the phenyl groups were preprared by coupled oxidation of tetraarylporphyrin iron complexes. The yields of 5,10,15-triaryl-19-aroyl-15-hydroxybiladien-ab-ones were 74% (R=H), 85% (R=OMe), 44% (R=COOMe), and 28% (R=CN). Kinetic studies of the iron porphyrin oxidation revealed that the reaction is accelerated by an electron-withdrawing substituent with the Hammett reaction constant rho=0.295. 5,10,15-Triaryl-19-aroyl-15-hydroxybiladien-ab-ones undergo the acid-catalyzed elimination reaction either by acetic acid or by mesoporous silica to afford 5,10,15-triaryl-19-aroylbilatrien-abc-one. The elimination reaction in acetic acid is accelerated by an electron-donating substituent with the Hammett reaction constant rho=-1.48.
authors.affiliation: Department of Molecular Science and Technology, Faculty of Engineering, Doshisha University, Tatara-Miyakotani, Kyotanabe, Kyoto 610-0321, Japan.
authors.forename: Naomi
authors.initials: N
authors.lastname: Asano
authors.forename: Sayo
authors.initials: S
authors.lastname: Uemura
authors.forename: Tomoya
authors.initials: T
authors.lastname: Kinugawa
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Akasaka
authors.forename: Tadashi
authors.initials: T
authors.lastname: Mizutani