Oligocyclization of 2-(hydroxymethyl)pyrroles with electron-withdrawing groups at beta-positions: formation and structural elucidation of porphyrinogens and hexaphyrinogens.
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.
Uno
Hidemitsu
H
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
Inoue
Kentarou
K
Inoue
Takashi
T
Ono
Noboru
N