5,6-Di(meth-d3-oxy)indane-1,3-dione is the labeled analogue of 5,6-Dimethoxyindane-1,3-dione (D447457), an intermediate in the synthesis of 3-keto Donepezil(K181665), an impurity of Donepezil (D531750), a nootropic. An inhibitor of acetylcholinesterase.