To provide a compound expectable of remission and reduction of adverse effects such as vomiting, diarrhea and nightmare rarely observed after administration of donepezil hydrochloride.

The compound is represented by the general formula [wherein, R represents an optionally substituted 1-6C alkyl group, a carbamoyl group optionally substituted with one or two 1-6C alkyl groups, an aryloxycarbonyl group optionally substituted with one to three substituents, a 2-6C alkanoyl group optionally substituted with one to three substituents or an optionally substituted arylcarbonyl group; and n represents an integer of 0 or 1] or a pharmaceutically acceptable salt thereof.