Oligocyclization of 2-(hydroxymethyl) pyrroles with electron-withdrawing groups at β-positions: formation and structural elucidation of porphyrinogens and …
Acid-catalyzed oligomerization of 2-(hydroxymethyl) pyrroles bearing C6F5, 2, 6-Cl2C6H3, CF3 and CO2Et groups at β-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 β-substituents were sufficiently bulky, for example, mesityl, 2, 6-Cl2C6H3 and C6F5 groups. On the other hand, the pyrroles having ...