| abstract |
The present invention belongs to the pharmaceutical field, and specifically relates to PDE9 inhibitors represented by the formula (I), or pharmaceutically acceptable salts, stereoisomers, and their agents, drug compositions and applications. .. X 1 , X 2 , X 3 , X 4 , R 1 , R 2 , rings A, L and m are defined as specified herein. The above compounds are used to prepare pharmaceuticals that treat or prevent related diseases mediated by PDE9. [Chemical 1] [Selection diagram] None |