New Macrocyclic Ligands. XVI. Synthesis of a Series of N-Benzylated Macrocycles Incorporating N4O2-Donor Set

Abstract

The synthesis of five 20-membered, N-benzylated macrocyclic ligands incorporating N₄O₂-donor sets and from one to three benzyl substituents for use in metal-ion recognition studies is described. The new derivatives were obtained by both benzylation of the pre-formed parent macrocycle using benzyl chloride in acetonitrile in the presence of base or, in one case, by performing macrocyclic ring closure using the appropriate N-benzylated triamine precursor by means of a bis-Schiff base condensation with the corresponding dialdehyde, followed by in situ reduction of the diamine linkages so formed. The single crystal X-ray structure of the symmetrically substituted, di-N-benzylated derivative is reported.