A concise synthesis of multiply fused phenanthroline diamide (fused-PTDA) by palladium-catalyzed intramolecular C–H arylation. Highly efficient and selective extraction performance of fused-PTDA toward early lanthanides

The reaction of phenanthroline diamide bearing a bromoaryl moiety on the amide substituent in the presence of palladium catalyst proceeded efficiently to afford multiply-fused phenanthroline derivatives through intramolecular C–H arylation. The obtained diamide derivatives was found to extract lanthanide remarkably highly efficiently with distribution ratio (D: up to ca. 500) and it was also found show the metal-selective extraction (separation factor SF = up to 4.4).