Phenol‐based acyclic ligand 1,6‐bis(2‐chlorobenzyl)‐2,5‐bis(2‐hydroxy‐3‐formyl‐5‐methylbenzyl)‐2,5‐diazahexane, LH2 and its dilithium form Li2L possessing two dissimilar compartments having multifunctional groups were prepared through a Mannich reaction. To synthesize this ligand first, diamine compound 1,6‐bis(2‐chlorobenzyl)‐2,5‐diazahexane was prepared and then in a one‐step procedure an equivalent of diamine and two equivalents of 4‐methyl‐2‐formylphenol in the presence of an excess amount para‐formaldehyde were reacted. All characterization data for the new compounds including diimine, diamine, LH2 and Li2L are reported.