AZA-peptide protease inhibitors

A compound of formula (I),

• wherein,
• X1 and X2 are each independently —C(O)—;
• Y is —O—;
• L1 is —O—, alkylene, substituted alkylene, alkenylene, substituted alkenylene, alkynylene, or substituted alkynylene;
• L2 is a covalent bond or —NR8—;
• with the proviso that when L1 is alkylene and L2 is a covalent bond, R1 is not a substituted heterocyclyl selected from the group of heterocyclyls consisting of:
• wherein U and V are independently O, S, or NH;
• n is 1 or 2;
• L3 and L5 are each independently a covalent bond, alkylene or substituted alkylene;
• L4 and L6 are each independently a bond, or —O—;
• Ar1 and Ar3 are each independently aryl or substituted aryl;
• Ar2 is heterocyclyl or sybstituted heterocyclyl;
• R1 is cycloalkyl, substituted cycloalkyl, cycloalkenyl, substituted cycloalkenyl, heterocyclyl, substituted heterocyclyl, or —C(O)OR9;
• R2, R4 and R5 are H;
• R3 is —OH;
• R6 and R6a are each independently H, halo, cyano, alkyl, substituted alkyl, haloalkyl, substituted haloalkyl, alkenyl, substituted alkenyl, alkynyl, substituted alkynyl, heterocyclyl, substituted heterocyclyl, aryl, substituted aryl, heteroaryl, or substituted heteroaryl;
• R8 is H, alkyl, or substituted alkyl;
• R9 is H, alkyl, substituted alkyl, alkenyl, substituted alkenyl, alkynyl, or substituted alkynyl;
• m is 0 or 1;
• n is 0, 1 or 2;
• or a pharmaceutically acceptable salt, and/or ester thereof.