Patent ID: 7879889

Claim:
A method of treating senile dementia, which comprises administering to a patient in need of said treatment an effective amount of a compound of formula I or a pharmaceutically acceptable salt thereof: in which, X represents an oxygen or sulfur atom; R 1 represents a C 1-10 alkyl group optionally substituted with a C 3-7 cycloalkyl, a phenyl or a thienyl; or R 1 represents a C 3-7 cycloalkyl, thienyl, pyridinyl or pyrimidinyl group; the thienyl groups being optionally substituted with one to three C 1-3 alkyl groups; the phenyl group being optionally substituted with one to five halogen atoms or C 1-3 alkyl, C 1-3 alkoxy, C 1-3 fluoroalkyl or C 1-3 fluoroalkoxy groups; R 2 represents a C 1-6 alkyl group optionally substituted with a C 3-7 cycloalkyl, phenyl, C 1-3 alkoxy or hydroxyl group; or R 2 represents a C 3-7 cycloalkyl, piperidinyl, phenyl or pyridinyl group; the C 3-7 cycloalkyl and piperidinyl groups being optionally substituted with one or more C 1-3 alkyl, C 1-3 alkoxy, hydroxyl, C 1-3 fluoroalkyl or C 1-3 fluoroalkoxy groups; the phenyl and pyridinyl groups being optionally substituted with one or more halogen atoms or C 1-3 alkyl, C 1-3 alkoxy, hydroxyl, C 1-3 fluoroalkyl or C 1-3 fluoroalkoxy groups; R 3 represents a hydrogen atom or a C 1-6 alkyl group optionally substituted with a C 3-7 cycloalkyl group; R 4 represents a hydrogen atom or a C 1-6 alkyl group; R 5 and R 5′ represent, independently of each other, a hydrogen or halogen atom, a hydroxyl or C 1-3 alkyl group; or R 5 and R 5′ form together an oxo or oxime group such as: where R 7 represents a hydrogen atom or a C 1-3 alkyl; n represents an integer ranging from 0 to 3; and R 6 represents independently of each other when n=2 or 3, a hydrogen or halogen atom, a hydroxyl, C 1-3 alkyl, C 1-3 alkoxy, C 1-3 fluoroalkyl or C 1-3 fluoroalkoxy group.