Straightforward Synthesis of Oligopyrroles through a Regioselective S_NAr Reaction of Pyrroles and Halogenated Boron Dipyrrins

A novel stepwise and regioselective nucleophilic aromatic substitution (S_NAr) reaction of halogenated boron dipyrrins (BODIPYs) with pyrroles has been developed under mild conditions with no catalyst needed and shown to be diversity oriented. The resultant pyrrole-substituted BODIPYs are interesting red and near-infrared (NIR) fluorescent dyes with absorption maxima up to 733 nm. Removal of the BF₂ protecting group of the 3-pyrrole or 3,5-dipyrrole-substituted BODIPYs provides a facial entry to oligopyrroles with direct 2,2′-bipyrrole linkages