Abstract: The present invention is new excitatory amino acid antagonists (herein referred to as compounds of formula (1)): below: ##STR1## These new antagonists are useful as NMDA (N-methyl-D-aspartate) antagonists.

Abstract: A commercial scale process for the production of tetrahydroisoquinolines and related heterocyclics by reaction, in mildly acidic conditions, of aryl N-sulfonylethylamines in the presence of a suitable Lewis acid, and a compound capable of in situ generation of formaldehyde. The process is further characterized by formaldehyde being generated by the reaction of the Lewis acid upon the formaldehyde generating agent, instead of being present as an initial reactant. The process further avoids the presence of initial water which destroys the Lewis acid before it can act upon the formaldehyde generating agent.