5H-pyrrolo[2,3-D]pyrimidin-6(7H)-one derivative

A compound represented by Formula (I) or a salt thereof:

• wherein
• R1 represents an optionally substituted 4- to 6-membered monocyclic unsaturated heterocyclic group having 1 to 3 hetero atoms selected from among N, S, and O;
• R2 represents a hydrogen atom, a halogen atom, a hydroxyl group, an amino group, a cyano group, a nitro group, a C1-C6 alkyl group, a C1-C6 haloalkyl group, a C2-C6 alkenyl group, a C2-C6 alkynyl group, or a C3-C6 cycloalkyl group;
• R3, R4, and R5, which may be the same or different, each represent a hydrogen atom, a C1-C6 alkyl group, a C1-C6 haloalkyl group, or a C3-C6 cycloalkyl group;
• or R3 and R4, together with a nitrogen atom to which they are bound, form a 4- to 6-membered monocyclic saturated heterocycle having 1 to 3 hetero atoms selected from among N, S, and O, and R5 represents a hydrogen atom, a C1-C6 alkyl group, a C1-C6 haloalkyl group, or a C3-C6 cycloalkyl group;
• or R4 and R5, together with a nitrogen atom to which they are bound and a carbon atom adjacent thereto, form a 4- to 6-membered monocyclic saturated heterocycle having 1 to 3 hetero atoms selected from among N, S, and O, and R3 represents a hydrogen atom, a C1-C6 alkyl group, a C1-C6 haloalkyl group, or a C3-C6 cycloalkyl group;
• R6 represents a hydrogen atom, a C1-C6 alkyl group, a C1-C6 haloalkyl group, or a C3-C6 cycloalkyl group;
• R7 and R8, which may be the same or different, each represent a hydrogen atom, a halogen atom, a hydroxyl group, an amino group, a cyano group, a nitro group, a C1-C6 alkyl group, a C1-C6 haloalkyl group, a C2-C6 alkenyl group, a C2-C6 alkynyl group, or a C3-C6 cycloalkyl group;
• or R7 and R8, together with a carbon atom to which they are bound, form a C3-C10 cycloalkyl group;
• X1 and X2, which may be the same or different, each represent N or CR9, and R9 represents a hydrogen atom, a halogen atom, a hydroxyl group, an amino group, a cyano group, a nitro group, a C1-C6 alkyl group, a C1-C6 haloalkyl group, a C2-C6 alkenyl group, a C2-C6 alkynyl group, or a C3-C6 cycloalkyl group;
• and
• X3 represents N or CH when a broken line () indicates a single bond, or C when a broken line indicates a double bond, provided that at least either one of X1 or X2 represents N.