AN EFFICIENT, HIGH-YIELD PREPARATION OF SUBSTITUTED 2,2'-BIPYRROLES

An improved synthesis of alkyl substituted 2,2'-bipyrroles is describe d. It involves first pyrrolic nitrogen protection of substituted 2-iod opyrroles, then Ullmann-type coupling, followed finally by deprotectio n of the resulting 2,2'-bipyrroles. Using this procedure, yields of 2, 2'-bipyrroles are typically enhanced by 20 to 30% depending on the pyr role ring substitution and the scale of the reaction.