FIELD: medicine.SUBSTANCE: invention relates to a novel compound of formula I or a pharmaceutically acceptable salt thereof having a selective impact on PDE1. In formula IX represents -CH- or -N-； Y - O- or -S-； M is 0-3； each of R1 is independently selected from the group consisting of: H, halogen, -C1-6alkyl, -C1-6haloalkyl, -C1-6alkoxy, -C1-6haloalkoxy, and phenyl； each of R3 and R4 is independently selected from the group consisting of: -H； halogen； -C1-6alkyl； -C1-6haloalkyl； -CH2OH； -C1-6alkoxy； -C1-6haloalkoxy； optionally substituted 5- or 7-membered heteroaryl having 1-3 heteroatoms selected from: N, O, or S, in which the substituents are independently selected from C1-C6alkyl, HOCH2, halogen, -CH2N(C1-C4alkyl)-C(=O)-, N(C1-C4alkyl)2, -CH2N(C1-C4alkyl)2, benzyl, -CH2-5-7-membered monoheterocycloalkyl having 1 to 2 heteroatoms selected from N, O, optionally substituted C1-C4alkyl, oxo, C1-C4alkylsulfonyl, or -CH2-5-6-membered monoheterocycloalkyl having a nitrogen atom in the ring condensed with a benzene ring, or -CH2-7-9-membered bicyclic heterocycloalkyl having 1 to 2 heteroatoms selected from N or O； -(C1-C6alkyl)phenyl； -(C1-C6alkyl)-5-6-membered heteroaryl having 1 to 2 heteroatoms selected from N and O, and -(CR10R11)1-3NR12R13； or R3 and R4, taken together with the carbon atoms to which they are attached, form a saturated or unsaturated monocyclic ring system having the following structure: where D is a bond, or -O-, or -N(R9)-, where R9 represents -H, -C1-6alkyl, -halogen-C1-6alkyl, -C1-6alkylthiomethyl, -C1-6alkyl-SO2methyl, -C1-6alkoxyC1-6alkyl, -halogen1-6alkoxyalkyl, -C1-6alkylphenyl, -C1-6alkyl (C3-6cycloalkyl), -C1-6alkyl (4-6-membered saturated heterocycloalkyl with 1-2 heteroatoms, selected from N and O), -C1-6alkyl(phenyl, optionally condensed with 5-6 membered saturated heterocycloalkyl with 1-2 heteroatoms, selected from O), C1-6alkyl (5-6 membered heteroaryl with 1 to 3 heteroatoms selected from N, S or -SO2) or 4-6 membered heterocycloa
