Synthesis of highly hindered polyanionic chelating ligands

Practical and efficient protocols to obtain highly hindered polyanionic chelating ligands based on bis-(3,5-di-tert-butyl-2-hydroxybenzamido) compounds are reported here. N-3,5-di-tert-Butylsalicyloyloxysuccinimide was treated with aliphatic diamines to form aliphatic hydrocarbon-linked bis-amides . Aromatic diamines required more powerful electrophile, thus the corresponding benzylated acid chloride was used to form aromatic hydrocarbon-linked bis-amides . The yields ranged from good to very good and showed that choosing the right acylating agent is a key point in this synthesis. All the compounds were characterized by elemental analysis, IR, MS and NMR.