title: Oligocyclization of 2-(hydroxymethyl)pyrroles with electron-withdrawing groups at beta-positions: formation and structural elucidation of porphyrinogens and hexaphyrinogens.
abstract: Acid-catalyzed oligomerization of 2-(hydroxymethyl)pyrroles bearing C6F5, 2,6-Cl2C6H3, CF3 and CO2Et groups at beta-positions was examined. The reaction of ethyl pyrrole-3-carboxylates gave a mixture of oligomers and type I isomers of porphyrinogens and hexaphyrinogens were isolated when the other beta-substituents were sufficiently bulky, for example, mesityl, 2,6-Cl2C6H3 and C6F5 groups. On the other hand, the pyrroles having other electron-withdrawing groups afforded porphyrinogens as the only isolable products.
authors.affiliation: Division of Synthesis and Analysis, Department of Molecular Science, Integrated Center for Sciences (INCS), Ehime University, Matsuyama 790-8577, Japan. uno@dpc.ehime-u.ac.jp
authors.forename: Hidemitsu
authors.initials: H
authors.lastname: Uno
authors.forename: Kentarou
authors.initials: K
authors.lastname: Inoue
authors.forename: Takashi
authors.initials: T
authors.lastname: Inoue
authors.forename: Noboru
authors.initials: N
authors.lastname: Ono