Azacycloalcane derivatives having general formula (I) wherein R1 and R2 represent a hydrogen atom, an alkyl group or a phenyl group, or R1 and R2 form together an oxo group, R3 is a hydrogen atom or an alkyl group, or R3 forms a methylene group, R4 is an aromatic group or, when R3 forms a methylene group, R4 is a phenylene group of which a carbon atom is bound to Y and another carbon atom adjacent