abstract |
The present invention relates to the technical field of medicine, and relates in particular to PDE9 inhibiting compounds represented by formula (I) or pharmaceutically acceptable salts or stereoisomers thereof. The invention also relates to pharmaceutical preparations and compositions of the compounds and their uses. X1, X2, X3, X4, R1, R2, ring A, L and m being as defined in the description. The compounds can be used to prepare drugs for the treatment or prevention of PDE9-related diseases. |