Substituted dibenzo[b, f]azepines as proteasome activators

A compound of formula (II):

• or a pharmaceutically acceptable salt thereof,
• wherein:
• X3 is —CH2CH2—;
• R1 is H, halo, alkyl, O(alkyl), aryl, or O(aryl);
• R2 is H, halo, alkyl, O(alkyl), aryl, or O(aryl);
• R4 is halo, alkyl, O(alkyl), or S(alkyl);
• R5 is C(O)NR6R7 or C(O)OR6;
• R6 is H, alkyl, or aryl;
• R7 is H, alkyl, or aryl;
• or
• R6 and R7, taken together with the nitrogen atom to which they are attached, form a heterocyclyl;
• and
• n is 1.