Synthesis of bis(azafulvene)s by dehydration of hydroxymethylpyrrole derivatives

Bis(azafulvene) was isolated in 55% yield by the reaction of 4 equivalents of phenyllithium with 5,5′-diformyl-3,3′,4,4′-tetraethyl-2,2′-bipyrrole followed by quenching with acetic anhydride. Unstable bis(azafulvene)s were obtained in much higher yields by dehydrating 5,5′-bis(hydroxymethyl) derivatives of 2,2′-bipyrrole and gem-dimethyl-2,2′-dipyrrylmethane with (Boc)₂O–DMAP at room temperature. X-Ray crystallography of two bis(azafulvene)s is reported.