Compounds useful as reversible inhibitors of cathepsin S

This invention relates to peptidyl cysteine protease inhibitors. The compounds are reversible inhibitors of the cysteine protease cathepsin S and are therefore useful in the treatment of autoimmune diseases. The invention also relates to processes for preparing such compounds and pharmaceutical compositions comprising them. Disclosed are cathepsin S reversible inhibitory compounds of the formulas (I),(Ia) and (II),(IIa) as defined herein. The compounds are useful for treating autoimmune diseases. Also disclosed are processes for making such novel compounds