Synthesis and cognition-activating properties of some mono- and bicyclic lactam derivatives

Upon reductive cyclization cyano esters 2, 3, and 9 yielded piperidones and perhydropyrrolo[3,4-c]pyridine lactams, generally as a mixture of diasteromeric cis-trans forms. X-ray crystallographic analyses were carried out on bicyclic dilactam derivatives 6 and 10, and a cis configuration at the ring junction was determined in both cases. A series of neuropsychopharmacological tests performed on the title compounds indicated that they are generally nontoxic even at high doses (up to 1000 mg/kg ip). The cognition activating properties of lactams 4, 5, 6, and 10 were evaluated in enhancing retention for passive avoidance learning in rats without and after electroconvulsive shock (ECS); compounds 5 and 10 were found to be more potent than piracetam in the amnesia-reversal testing.