Cysteine protease inhibitors

A compound of the formula I:

• wherein
• R2a and R2b are independently selected from H, halo, C1-C4alkyl, C1-C4haloalkyl, C1-C4alkoxy, or R2a and R2b 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;
• or
• R3 is a C2-C4alkyl chain with at least 2 chloro or 3 fluoro substituents;
• or
• R3 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 independently selected from:
• halo, azido, cyano, hydroxy, oxo, C1-C4alkyl, C1-C4haloalkyl, C1-C4alkoxy, C1-C4haloalkoxy, C1-C4alkoxycarbonyl, C1-C4alkylcarbonyl, C1-C4alkylsulfonyl, C1-C4alkylsulfonylamino, aminosulphonyl, NRaRb, C(═O)NRaRb, NRaC(═O)Rb, NRaC(═O)ORb, NRa(C═O)NRaRb, wherein oxo as substituent may be present only where valence so permits;
• and/or wherein in the Het or Carbocyclyl group is optionally substituted with a group of the formula —X—R5;
• wherein
• X is C1-C4alkylene or a 1-4 membered linkage comprising 0-3 methylene groups disposed adjacent to, or on either side of a —CH(CH3)—, —C(CH3)2—, CF2—, —O—, —CH═CH—, —C≡C—, —NRa-, —C(═O)NRa-, —NRaC(═O)—, —C(═O)NRa-, —NRaS(═O)2—, —S(═O)2NRa-, ester, urea or carbamate function;
• R5 is H, C1-C4alkyl or a monocyclic ring selected from C3-C6cycloalkyl, C3-C6cycloalkenyl, phenyl, pyrrolidinyl, piperidinyl, morpholinyl, thiomorpholinyl, piperazinyl, indolinyl, pyranyl, tetrahydropyranyl, tetrahydrothiopyranyl, thiopyranyl, furanyl, tetrahydrofuranyl, thienyl, pyrrolyl, oxazolyl, isoxazolyl, thiazolyl, imidazolyl, pyridinyl, pyrimidinyl, pyrazinyl, pyridazinyl, tetrazolyl, pyrazolyl, indolyl, the C1-C4alkyl or monocyclic ring being optionally substituted with one to three substituents selected from:
• halo, azido, cyano, hydroxy, C1-C4alkyl, C1-C4haloalkyl, C1-C4alkoxy, C1-C4haloalkoxy, C1-C4alkoxycarbonyl, C1-C4alkylcarbonyl, amino, C1-C4alkylamino, C1-C4dialkylamino, C1-C4alkylsulfonyl, C1-C4alkylsulfonylamino, aminocarbonyl, aminosulphonyl;
• n is 1, 2 or 3;
• Ra and Rb are independently H, C1-C4alkyl;
• Het is a stable, monocyclic or bicyclic, saturated, partially saturated or aromatic ring system containing 1-4 heteroatoms independently selected from O, S and N, each ring having 5 or 6 ring atoms;
• Carbocyclyl is C3-C6cycloalkyl, C5-C6cycloalkenyl or phenyl;
• or a pharmaceutically acceptable salt, hydrate or N-oxide thereof.