A compound represented by formula [I] and a pharmaceutically accepted salt of said compound are a novel compound and a phamaceutically accepted salt thereof which exert antagonistic activity against group II metabotropic glutamate (mGlu) receptors, and are effective as a novel preventive or therapeutic agent for disorders such as mood disorders (depressive disorder, bipolar disorder, etc.), anxiety disorders (generalized anxiety disorder, panic disorder, obsessive-compulsive disorder, social anxiety disorder, posttraumatic stress disorder, a specific phobic disorder, acute stress disorder, etc.), schizophrenia, Alzheimers disease, cognitive impairment, dementia, drug dependence, convulsions, shivering, pain, sleep disorders, and the like.
