FIELD: chemistry.SUBSTANCE: compounds are the inhibitors of phosphodiesterase 9 (PDE9). In formulaX is selected from a bond； R1 is selected in an independent way from the group, consisting of (C1-C6)alkyl； R2 is selected in an independent way from the group, consisting of (C1-C6)alkyl, (C3-C10)cycloalkyl, heterocycloalkyl, containing 6 atoms in a ring, where 1 atom in the ring is selected from O or N； heteroaryl, containing 5-6 atoms in a ring, where 1 atom in the ring is selected from O or N； phenyl； each of which can in some cases be substituted with one or several substituents, selected from the group, consisting of a halogen, -S(O)2(C1-C4)alkyl, OH, -C(O)-(C1-C4)alkyl, (C1-C6)alkyl； and R3 is selected in an independent way from the group, consisting of (heteroaryl, containing 6 atoms in a ring, where 1-2 atoms in the ring are selected from N)(C1-C4)alkyl； (bicyclic heteroaryl, containing 9-10 atoms in a ring, where 1-3 atoms in the ring are selected from N)(C1-C4)alkyl； phenyl； phenyl(C1-C4)alkyl； each of which can in some cases be substituted with one substituent, selected from the group, consisting of a halogen, CN, (C1-C4)alkoxy. The invention also relates to a different version of formula (I) compounds, to individual compounds, to a pharmaceutical composition, to the method of treating a PDE9-associated disease or disorder and to the method for PDE inhibition.EFFECT: improvement of the properties of the compounds.21 cl, 2 tbl, 58 exИзобретение относится к соединениям формулы (I) и его фармацевтически приемлемым солям. Соединения являются ингибиторами фосфодиэстеразы 9 (ФДЭ9). В формуле (I)X выбирают из связи； R1 выбирают независимым образом из группы, состоящей из (С1-С6)алкила； R2 выбирают независимым образом из группы, состоящей из (С1-С6)алкила, (С3-С10)циклоалкила, гетероциклоалкила, содержащего 6 атомов в кольце, где 1 атом в кольце выбирается из О или N； гетероарила, содержащего 5-6 атомов в кольце, где 1 атом в кольце выбирается из О или N； фенила；
