摘要 |
Compounds of formula (I) and their pharmaceutically acceptable salts are useful as histamine H3 receptor ligands. R1 and R3 are optional substituents such as C1 to C6 alkyl. R2 represents a bond or C1 to C5 (preferably C1 to C3) hydrocarbylene; R4 represents a bond or C1 to C5 (preferably C1 to C3) hydrocarbylene; R5 is hydrogen, C1 to C3 alkyl, R8-O-(C1 to C3)alkyl (wherein R8 is hydrogen or C1 to C3 alkyl), aryl, aryl(C1 to C3)alkyl; R6 represents a bond or -NR9-, wherein R9 is any of the groups mentioned above for R5; R7 is H or C1 to C15 hydrocarbyl (in which one or more hydrogen atoms may be replaced by halogen, and up to three carbon atoms may be replaced by oxygen, nitrogen or sulfur atoms); a is from 0 to 2; and b is from 0 to 3. |