Substituted pyrrolizine-bridged bipyrroles synthesis via ring annulation under green conditions

Several new substituted 2,3-dihydro-1H-pyrrolizine-bridged bipyrroles were synthesized via ring annulation under green aqueous conditions. In this work, the acid-catalyzed condensation of the used diketones with pyrrole did not result in the formation of expected divergent bisdipyrromethanes. However, new important pyrrolizine-bridged bipyrroles were synthesized in good yields. Ferric hydrogensulfate was used as an environmentally friendly homogeneous acidic catalyst to produce pure products in aqueous conditions. This catalyst has enabled us to synthesize pyrrolizine-bridged bipyrroles with bearing functional groups at designated positions. These synthesized compounds can be used for various unknown and known applications such as chiral catalysts and essential biological activities.