Fused bicyclic-substituted amines as histamine-3 receptor ligands

A compound of the formula:

• or a pharmaceutically acceptable salt, ester, amide, or prodrug thereof, wherein:
• X is O, S, NH, or N(alkyl);
• Y, and Y′ are each independently selected from the group consisting of CH, CF, and N;
• Z is C or N, provided that when X is O or S, Z is N;
• one of R1 and R2 is selected from the group consisting of heteroaryl, and heterocycle;
• the other of R1 and R2 is selected from the group consisting of hydrogen, alkyl, and alkoxy;
• R3 is absent when Z is N and, when present, R3 is selected from the group consisting of hydrogen, methyl, alkoxy, halo, and cyano;
• R4 and R5 taken together with the nitrogen atom to which each is attached form a non-aromatic ring of the structure (a):
• R7, R8, R9, and R10 are each independently selected from the group consisting of hydrogen, hydroxyalkyl, fluoroalkyl, and alkyl;
• R11, and R12 are each independently selected from the group consisting of hydrogen, hydroxy, hydroxyalkyl, alkyl, and fluoro;
• R13 and R14 at each occurrence are independently selected from the group consisting of hydrogen, alkyl, and fluoro;
• L is —[C(R15)(R16)]n—;
• R15 and R16 at each occurrence are independently selected from the group consisting of hydrogen, alkyl, alkoxy, and fluoro;
• m is 1;
• and
• n is an integer from 2–3.