Patent ID: 8569353

Claim:
A compound of Formula (1): or a pharmaceutically acceptable salt thereof wherein R 1 and R 2 are independently selected from the group consisting of hydrogen atom, a C 1-6 alkyl group and a C 3-8 cycloalkyl group, R 3 and R 4 are independently selected from the group consisting of hydrogen atom and a C 1-6 alkyl group, R 5 is an optionally-substituted C 4-7 alkyl group or —(CR 8 R 9 ) r -E, R 6 , R 7 , R 8 and R 9 are independently selected from the group consisting of hydrogen atom, fluorine atom and an optionally-substituted C 1-6 alkyl group, A is an optionally-substituted C 6-10 aryl group or an optionally-substituted 5- to 10-membered heteroaryl group, r is 1, 2, 3 or 4, E is an optionally-substituted C 3-8 cycloalkyl group, an optionally-substituted C 4-8 cycloalkenyl group, an optionally-substituted 5- to 10-membered saturated heterocyclic group which comprises 1 to 3 heteroatoms independently selected from the group consisting of oxygen atom and sulfur atom as a constituent atom of the ring, an optionally-substituted C 6-10 aryl group or an optionally-substituted 5- to 10-membered heteroaryl group, L is oxygen atom, sulfur atom or —NR 10 —, n is 1, 2 or 3, R 10 is hydrogen atom, a C 1-6 alkyl group or a C 3-8 cycloalkyl group, and X is hydrogen atom, a C 1-6 alkyl group optionally-substituted with fluorine atom or a halogen atom.