1-substituted tetrahydroisoquinoline compound

A compound of the formula (I):

• wherein the symbols in the formula have the following meanings:
• R1a and R1b:
• are the same or different and may be —H, C1-6 alkyl which may be substituted, cycloalkyl which may be substituted, aryl which may be substituted, or an aromatic hetero ring which may be substituted, provided that both of R1a and R1b cannot be —H, and R1a and R1b, when taken together with the carbon atom to which they are attached, may represent cycloalkyl which may be substituted,
• R3a, R3b, R4a and R4b:
• are the same or different and may be —H, or C1-6 alkyl,
• R5, R6, R7 and R8:
• are the same or different and may be —H, C1-6 alkyl which may be substituted, —O—(C1-6 alkyl) which may be substituted, cyano, carbamoyl which may be substituted with one or two C1-6 alkyl, or halogen, and any two adjacent groups of R5, R6, R7 and R8 when taken together may form —O—CH2—O— or —O—(CH2)2—O—,
• R11, R12, R13, R14, R15 and R16:
• are the same or different and may be —H or C1-6 alkyl,
• R21:
• is —H, C1-6 alkyl which may be substituted, or cycloalkyl which may be substituted,
• R22:
• is
• (1) cycloalkyl which is substituted with one or more groups selected from the group consisting of —OH and —CH2OH and which may be further substituted;
• (2) C1-8 alkyl substituted with one or two —OH, wherein the C1-8 alkyl may further have a substituent, and one or two methylene groups (—CH2—) contained in this alkyl chain may be replaced with —O—;
• or
• (3) C1-6 alkyl substituted with cycloalkyl which is substituted with one or more groups selected from the group consisting of —OH and —CH2OH and which may be further substituted, wherein the C1-6 alkyl may be substituted with —OH, and one or two methylene groups (—CH2—) contained in this alkyl chain may be replaced with —O—;
• and
• n and m:
• are the same or different and are 0 or 1,
• wherein R12 and R21 when taken together may form methylene, ethylene, or trimethylene, and in this case, R11 may represent —OH, or
• R21 and R22, when taken together with the nitrogen atom to which they are attached, may form azetidine, pyrrolidine, piperidine, azepane, azocane, morpholine, tetrahydroisoquinoline or thiomorpholine which are substituted with —OH or C1-6 alkyl substituted with —OH;
• or a pharmaceutically acceptable salt thereof.