A series of 4-aminomethyl-1,2,3,4-tetrahydroisoquinoline derivatives were prepared as potential CNS-agents acting via amino-acid neurotransmitter systems. The compounds were synthesized from 1,2,3,4-tetra-hydro-1-oxoisoquinoline-4-carboxylic acids obtained by dipolar cycloadditon reactions of imines with homophthalic anhydride. Among the compounds testes 5c and 5m showed sub-micromolar affinity for the NMDA receptor and represent a structurally novel class of ligand for this site.