<p>There is provided a method for preparing a compound 2-[(E)-l-(l-benzyl-4-piperidyl)methylidene]-5,6-dimethoxy-l-indanone that is an intermediate of donepezil that has been widely known as a therapeutic agent for treating dementia. The present invention is related to the method for preparing a compound 2-[(E)-l-(l-benzyl-4-piperidyl)methylidene]-5,6-dimethoxy-l-indanone by reacting a 5,6-dimethoxy-l-indanone compound with a l-benzyl-piperidine-4-carbaldehyde compound under a basic condition as in sodium alkoxide. The method for preparing an intermediate of donepezil according to the present invention may be useful to facilitate the commercial mass- production and enhance the production yield.</p>
