Benzofuran type derivatives, a composition comprising the same for treating or preventing cognitive dysfunction and the use thereof

A compound represented by general formula (I), or a pharmaceutically acceptable salt thereof:

• wherein
• R1 is a hydrogen atom, C1-C6 alkyl group, C2-C6 alkyl ketone group or —(CH2)n-Q, of which Q is an ether group or amine group substituted with C1-C6 lower alkyl group;
• R2 is a hydrogen atom, or an ether group or thio group substituted with C1-C6 alkyl group;
• R3 is
• wherein R′ is a hydrogen atom, or C1-C6 alkyl group,
• X is O, S or amine group unsubstituted or substituted with R″, of which R″ is benzyl ester or carboxyl group,
• n is an integer of 0-9;
• with the proviso that compound 3-[2-(3,4-dimethoxy-phenyl)-benzofuran -5-yl]propan-1-ol is excluded from the general formula I.