Synthesis and pharmacological properties of new derivatives of 2-amino-5-(2-amino-3-pyridyl)-1,3,4-oxadiazole

Reaction of 2-aminonicotinic acid hydrazide with cyanogen bromide allowed t o obtain 2-amino-5-(2-amino-3-pyridyl)-1,3,4-oxadiazole (2), which with 2- or 3-chloropropionyl chloride and 4-chlorobutyryl chloride gave 5-(2-amino- 3-pyridyl)-2-(2-chloropropionylamino)-1,3,4-oxadiazole (5), 5-(2-amino -3-p yridyl)-2-(3-chloropropionylamino) -1,3,4-oxadiazole (6) and 5-(2-amino-3-p yridyl)-2-(4-chlorobutyrylamino)-1,3,4-oxadiazole (7), respectively. Cycliz ation of chloroacyl derivative 7 led to 5-(2-amino-3-pyridyl)-2-(2-oxo-1-py rrolidinyl)-1,3,4-oxadiazole (9). Treatment of oxadiazole 2 with appropriat e alkylating agents (1,3-dibromopropane or 1,4-dibromobutane) gave 2-azetid inyl- 1,3,4-oxadiazole (10) or 2-pyrrolidinyl-1,3,4-oxadiazole (11). Compou nds 3, 4, 7, 10 and 11 were tested towards a psychotropic activity. Compoun d 10 showed anxiolytic properties and an antiserotonin action, which was co nfirmed in the test of the black-white box and the m-CPP test, respectively . Crystal structure was determined on a single crystal.