4-[1-(Phenylmethyl)-3-pyrrolidinyl]-1-piperazinecarboxylic Acid 1,1-Dimethylethyl Ester, is an intermediate in the synthesis of 4-(Pyrrolidin-3-yl)piperazine-1-carboxylic Acid tert-Butyl Ester (P998515). It is also a substituted indazole derivative,useful as ketohexokinase inhibitors or the treatment of diabetes, diabetic complications and other dieases.