Efficient synthesis of 6,6′-diamido-2,2′-dipicolylamine ligands for potential phosphate anion sensing

We report here the efficient synthesis of 6,6′-diamido-2,2′-dipicolylamines (DA-DPAs) which could be applied to phosphate anion sensing via pre-formed metal complexes. The design was based on the retrosynthetic analysis. This strategy enabled us to achieve the functionalized DA-DPAs in satisfactory yields with high purity using the Boekelheide rearrangement. Meanwhile, all the intermediates could be easily purified by silica gel column chromatography. Through retrosynthetic analysis, functionalized 6,6′-diamido-2,2′-dipicolylamines (DA-DPAs) have been efficiently synthesized, which may accelerate the development of selective probes towards phosphate anions.