Patent ID: 8263607

Claim:
A compound of the formula (I): wherein the symbols in the formula have the following meanings: R 1a and R 1b : are the same or different and may be —H, C 1-6 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 R 1a and R 1b cannot be —H, and R 1a and R 1b , when taken together with the carbon atom to which they are attached, may represent cycloalkyl which may be substituted, R 3a , R 3b , R 4a and R 4b : are the same or different and may be —H, or C 1-6 alkyl, R 5 , R 6 , R 7 and R 8 : are the same or different and may be —H, C 1-6 alkyl which may be substituted, —O—(C 1-6 alkyl) which may be substituted, cyano, carbamoyl which may be substituted with one or two C 1-6 alkyl, or halogen, and any two adjacent groups of R 5 , R 6 , R 7 and R 8 when taken together may form —O—CH 2 —O— or —O—(CH 2 ) 2 —O—, R 11 , R 12 , R 13 , R 14 , R 15 and R 16 : are the same or different and may be —H or C 1-6 alkyl, R 21 : is —H, C 1-6 alkyl which may be substituted, or cycloalkyl which may be substituted, R 22 : is (1) cycloalkyl which is substituted with one or more groups selected from the group consisting of —OH and —CH 2 OH and which may be further substituted; (2) C 1-8 alkyl substituted with one or two —OH, wherein the C 1-8 alkyl may further have a substituent, and one or two methylene groups (—CH 2 —) contained in this alkyl chain may be replaced with —O—; or (3) C 1-6 alkyl substituted with cycloalkyl which is substituted with one or more groups selected from the group consisting of —OH and —CH 2 OH and which may be further substituted, wherein the C 1-6 alkyl may be substituted with —OH, and one or two methylene groups (—CH 2 —) 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 R 12 and R 21 when taken together may form methylene, ethylene, or trimethylene, and in this case, R 11 may represent —OH, or R 21 and R 22 , 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 C 1-6 alkyl substituted with —OH; or a pharmaceutically acceptable salt thereof.