The invention provides a chemical entity of Formula (I): wherein R1, R2, R3, R4, X, and Y 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 GlyT1 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, including animal skill training and treating other disorders, including pain and alcohol-dependence.本發明提供一種式(I)之化學實體,其中R1、R2、R3、R4、X及Y具有本文所描述之任何值;及包含該等化學實體之組合物;製造其之方法;及其在廣泛範圍之方法中之用途,包括代謝及反應動力研究;偵測及成像技術;放射性治療;調節及治療由GlyT1活性介導之病症;治療神經病症、CNS病症、癡呆、神經退化性疾病及創傷相關功能喪失;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、包括動物技能訓練之功效;及治療其他病症,包括疼痛及酒精依賴。