Synthesis of pyrrolyldipyrrinato BF2 complexes by oxidative nucleophilic substitution of boron dipyrromethene with pyrrole.

Direct oxidative nucleophilic substitution of the 3-hydrogen of BODIPY dyes by pyrrole has been developed under reflux condition under oxygen, from which a series of pyrrolyldipyrrinato BF2 complexes 1a-h, as extended BODIPYs, have been synthesized. Most of these BODIPYs show strong fluorescence emissions at wavelengths over 600 nm in six solvents of different polarity. Removal of the BF2 group from BODIPY 1e gave the corresponding free base pyrrolyldipyrrin 7 as an analog of the natural product prodigiosin, in high yield.