Synthesis of 2′,2′-dibromovinyl porphyrins and their versatile use in Pd-catalyzed cross-coupling reactions

The chemistry of 1,1-dibromovinyl functional groups has undergone a renaissance through the application of palladium catalysis. In this study we applied this chemistry to pyrrole derivatives. Thus, this paper focuses on the synthesis of 2′,2′-dibromovinyl porphyrins substituted at either the meso- or β-position of the pyrrole rings directly or through a spacer. Post-functionalization of 2′,2′-dibromovinyl porphyrins through organometallic methodologies were studied for cross-coupling reactions using Sonogashira, Suzuki, Heck and Stille conditions and with phosphonates. The assigned structures are supported by HRMS analysis and ¹H NMR, ¹³C NMR and X-ray diffraction analysis. The conjugates were investigated for their optical properties. Structural modifications through substitution at different positions of the porphyrin macrocycle and their substitution patterns significantly influence the optical properties of the porphyrins.