Compounds of the formula II: wherein R2 is the side chain of leucine, isoleucine, cyclohexylglycine, O-methyl threonine, 4-fluoroleucine or 3-methoxyvaline； R3 is H, methyl or F； Rq is trifluoromethyl and Rq&prime； is H or Rq and Rq&prime； define keto； Q is a p-(C1-C6alkylsulphonyl)phenyl- or an optionally substituted 4-(C1-C6alkyl)piperazin-1-yl-thiazol-4-yl- moiety have utility in the treatment of disorders characterized by inappropriate expression or activation of cathepsin K, such as osteoporosis, osteoarthritis, rheumatoid arthritis or bone metastases.
