In this work, the indirect reductive amination of terephthalaldehyde with aqueous ammonia was studied. The condensation of terephthalaldehyde with ammonia afforded a new compound containing two aldehyde groups (CHO), one imino group (C=N), and an aminal carbon (N–CH–N). Reaction of this compound with sodium borohydride resulted in the reduction of the aldehyde groups, the imino carbon, and the aminal carbon. Analysis of the condensed Fukui functions and the LUMO orbital allowed us to propose a mechanism that explains this reactivity. Furthermore, a general mechanism for the condensation of aromatic aldehydes with aqueous ammonia is presented.