Substituted azetidin-2-ones as cysteine protease inhibitors

This application is National Stage entry of International Application No. PCT/GB00/01261, filed Apr. 3, 2000, the entire specification claims and drawings of which are incorporated herewith by reference. This invention relates to substituted azetidin-2-ones and to pharmaceutical compositions containing such compounds. Their use in medicine as inhibitors of cysteine proteases, particularly the cathepsins is also described. The invention includes a compound of formula (I), Y represents -C(O)- or -S(O)-; R represents an allyl (ie CH CHCH-) group or a radical. Rrepresents -OCOR, -OR, -SR, -S(O)R, or -S(O)R; Rrepresents a radical. Rrepresents -ORor R; or a pharmaceutically acceptable salt, hydrate or solvate thereof.