The present invention provides compounds of formula (I) that are PDE1 enzyme inhibitors and their use as a medicament, in particular for the treatment of neurodegenerative disorders and psychiatric disorders. The present invention also provides pharmaceutical compositions comprising compounds of the invention and methods of treating disorders using the compounds of the invention.本發明提供了為PDE1酶抑制劑的具有式(I)之化合物及其作為藥劑特別是用於治療神經退行性障礙和精神障礙的用途。本發明還提供了包括本發明之化合物的醫藥組成物以及使用本發明之化合物治療障礙的方法。