The invention provides a chemical entity of Formula (I):, wherein R1, R2, R3, and R4, have any of the values described herein, and compositions comprising such chemical entities methods of making them and their use in a wide range of methods, including metabolic and reaction kinetic studies detection and imaging techniques radioactive treatments modulating and treating disorders mediated by PDE2 activity treating neurological disorders, CNS disorders, dementia, neurodegenerative diseases, and trauma-dependent losses of function treating stroke, including cognitive and motor deficits during stroke rehabilitation facilitating neuroprotection and neurorecovery enhancing the efficiency of cognitive and motor training and treating peripheral disorders, including hematological, cardiovascular, gastroenterological, and dermatological disorders.本發明提供一種式(I)化學實體:,其中R1、R2、R3及R4具有本文所描述值中之任何一者,及包含此類化學實體之組合物;其製造方法;及其於廣泛方法中之用途,包括代謝及反應動力學研究;偵測及成像技術;放射性治療;調節及治療由PDE2活性介導之疾病;治療神經障礙、CNS障礙、癡呆、神經退化性疾病及與創傷相關之功能喪失;治療中風(包括中風復健期間之認知及運動缺陷);促進神經保護及神經恢復;增強認知及運動訓練之效率;及治療周邊疾病(包括血液、心血管、腸胃及皮膚疾病)。
