Compounds of the formula IwhereinR2a and R2b are independently H, halo, C1-C4alkyl, C1-C4haloalkyl or C1-C4alkoxy, or R2a andR2b together with the carbon atom to which they are attached form a C3-C6cycloalkyl；R3 is a C5-C10 alkyl, optionally substituted with 1-3 substituents independently selected from halo, C1-C4haloalkyl, C1-C4alkoxy, C1-C4haloalkoxy； orR3 is a C2-C4alkyl chain with at least 2 chloro or 3 fluoro substituents； orR3 is C3-C7cycloalkylmethyl, optionally substituted with 1-3 substituents independently selected from C1-C4alkyl, halo, C1-C4haloalkyl, C1-C4alkoxy, C1-C4haloalkoxy；R4 is C1-C6alkyl, C1-C6haloalkyl, C1-C6alkoxy, C1-C6haloalkoxy, C1-C6alkylamino, C1-C6dialkylamino or；R4 is Het or Carbocyclyl, either of which is optionally substituted with 1-3 substituents R4 is Het, carbocyclyl, C1-C6alkyl, C1-C6haloalkyl, C1-C6alkoxy or C1-C6haloalkoxy；n is 1, 2 or 3；for the use in the prophylaxis or treatment of a disorder characterised by inappropriate expression or activation of cathepsin S.
