Novel Pyrido[3,4-d]pyrimidin-4-one and Pyrimido[5,4-d]pyrimidin-4-one Derivatives as TREM2 Agonists for Treating Parkinson’s Disease

Provided herein are novel pyrido[3,4-d]pyrimidin-4-one and pyrimido[5,4-d]pyrimidin-4-one derivatives as TREM2 agonists, pharmaceutical compositions, use of such compounds in treating Parkinson's disease, and processes for preparing such compounds.