| abstract |
A compound represented by the following general formula (1) or a salt thereof. R 1 represents a halogen atom and so on; R 2 and R 3 each represent a hydrogen atom and so on; R 4 and R 5 each represent a hydrogen atom and so on, or R 4 and R 5 may form an oxo group; R a and R b each represent a lower alkyl group optionally having a substituent and so on, or they may bind to each other to form a nitrogen-containing heterocyclic ring which may be substituted by one or plural R c ; R c represents an aryl group optionally having a substituent and so on; ring A represents a benzene ring and so on; and m represents 0, 1 or 2. |