METABOTROPIC GLUTAMATE RECEPTOR AGONIST AND NEW IMIDAZOBENZOTHIAZOLE DERIVATIVE

PROBLEM TO BE SOLVED: To obtain the subject medicine useful for preventing and treating epilepsy, ache, neurodegenerative diseases, etc., by including a specific imidazobenzothiazole derivative. SOLUTION: This metabotropic glutamate agonist contains an imidazobenzothiazole derivative of formula I (R1 is a lower alkyl or the like; R2 and R3 are each H or the like; A1 and A3 are each a bond or the like; A2 is a lower alkyl; R4 and R5 are each H or the like) or its pharmaceutically acceptable salt for example, 6-(tert-butoxycarbonylamino)-2-tert-butyl-7- hydroxymethylimidazo [2,1-b]benzothiazole}. The compound of formula I is obtained, for example, by reacting a compound of formula II with a compound of formula III (X is a halogen or the like) (for example, 1-bromo-3,3- dimethylbutan-2-one) in a solvent such as ethanol. The compound of formula I is, for example, orally administered preferably at a daily dose of 50-200 mg for an adult with one to several portions.