Quinolizidinyl derivatives of 5,11-dihydro-6H-pyrido[2,3-b][1,4]benzodiazepin-6-one as ligands for muscarinic receptors

Quinolizidinyl derivatives of the tricyclic systems characterizing pirenzepine and nuvenzepine, were prepared and tested as ligands for muscarinic M1, M2 and M3 receptors; 5,11-dihydro-11-[(S-lupinyl)-thioacetyl]-6H-pyrido[2,3-b][1,4]benzodiazepin-6-one exhibited IC50= 10 nM for M1 and 760 nM for both M2 and M3 subtypes. During the synthesis some interesting side compounds were isolated and characterized.