The present invention provides a compound which enhances the production of erythropoietin. The present invention provides a compound represented by the formula (1) wherein R 1 : an aromatic hydrocarbon ring group or an aromatic heterocyclic group R 2 : a hydrogen atom, an alkyl group, or a heterocycloalkyl group R 3 : a hydrogen atom or an alkyl group A: a hydrogen atom or a hydroxy group L: -NHCO- or -OCH 2 - and X: a nitrogen atom or =CH-.