2,3-Dihydro-5,6-dimethoxy-2-[(1-oxido-4-pyridinyl)methyl]-1H-inden-1-one is used in the preparation of 1-?benzyl-?4-?[(5,?6-?dimethoxy-?1-?indanon-?2-?yl)?methyl]?piperidine. Impurity of Donepezil (D531750); an intermediate as an anti-Alzheimer's agent.