Ethyl 4-oxo-1-piperidinecarboxylate is used in organic synthesis. For example, in the synthesis of quinolones with antibacterial activity and DNA-gyrase inhibition properties, as well as in Loperamide synthesis. Ethyl 4-oxo-1-piperidinecarboxylate is a Loratadine impurity (0.01 to 0.8%). Stress studies applied on Loratadine were demonstrated that ethyl 4-oxo-1-piperidinecarboxylate (Impurity H) might represent a degradation byproduct.