The present invention provides a novel method for producing a compound represented by general formula (VII) below or a pharmaceutically acceptable salt thereof or a synthetic intermediate thereof: wherein R2 represents a hydrogen atom or a halogen atom, Rc represents a C1-6 alkyl group, X represents a group selected from a heteroaryl group etc., R11 represents an atom or group selected from a hydrogen atom, a halogen atom, a C1-6 alkyl group, etc., R16 and R17 each independently represent an atom or group selected from a hydrogen atom, a C1-6 alkyl group, etc., and R15 represents a hydrogen atom or a C1-6 alkyl group.