The present invention relates to schizophrenia, Alzheimer's disease, cognitive dysfunction, dementia, anxiety disorder (generalized anxiety disorder, panic disorder, obsessive compulsive disorder, social anxiety disorder, post-traumatic stress disorder, specific Prevention, depression, drug dependence, convulsions, tremors, pain, Parkinson's disease, attention deficit / hyperactivity disorder, bipolar disorder, eating disorders, or sleep disorders Alternatively, a novel compound of the following formula [I] or a pharmaceutically acceptable salt thereof useful for treatment is provided. [Chemical 1]本発明は、グリシン取り込み阻害作用に基づいた統合失調症、アルツハイマー病、認知機能障害、認知症、不安障害（全般性不安障害、パニック障害、強迫性障害、社会不安障害、外傷後ストレス障害、特定の恐怖症、急性ストレス障害等）、うつ病、薬物依存、痙攣、振戦、疼痛、パーキンソン病、注意欠陥・多動性障害、双極性障害、摂食障害、又は睡眠障害等の疾患の予防又は治療に有用な新規な下記式［Ｉ］の化合物又はその医薬上許容される塩を提供する。 【化１】
