The present invention provides 4-substituted-2-azetidinone compounds,
bicyclic 2-5-diketopiperazine compounds, and pharmaceutical compositions
thereof that are potent, safe and effective neuroprotective agents. Due
to their strong central nervous system (CNS) activity, the compounds can
be used to enhance memory and to treat a variety of neurological
disorders. The compounds are particularly useful for treating
neurological disorders caused by, or associated with, CNS trauma.