The invention provides compounds with enhanced permeability for selectively inhibiting glycosidases, prodrugs of the compounds, and pharmaceutical compositions including the compounds or prodrugs of the compounds. The invention also provides methods of treating diseases and disorders related to deficiency or overexpression of O-GlcNAcase, accumulation or deficiency of O-GlcNAc.

The present invention is directed to compounds and pharmaceutical formulations comprising these compounds which are useful as O-linked N-acetylglucosaminidase (O-GlcNAcase) inhibitors, and thus may be useful for the treatment of certain disorders such as Alzheimer's disease including reducing NFTs and/or hyperphosphorylated tau. The invention is also directed to use of the compounds as O-GlcNAcase imaging agents.

A compound of formula I: ##STR00001## or a salt thereof, wherein: R.sup.1 is OC(H)(X)(CH.sub.2).sub.nC(O)OH; R.sup.2 is OH, N.sub.3, or N(H)C(O)CH.sub.3; or R.sup.1 and R.sup.2 together with the carbon atoms to which they are attached form ##STR00002## R.sup.3 is H, CH.sub.3, CH.sub.2C(O)OH, or CH.sub.2OH; X is H, CH.sub.3, CH.sub.2OH, or CH.sub.2C(O)OH; and
n is 0 or 1.

A compound of formula I: ##STR00001## or a salt thereof, wherein: R.sup.1 is OC(H)(X)(CH.sub.2).sub.nC(O)OH; R.sup.2 is OH, N.sub.3, or N(H)C(O)CH.sub.3; or R.sup.1 and R.sup.2 together with the carbon atoms to which they are attached form ##STR00002## R.sup.3 is H, CH.sub.3, CH.sub.2C(O)OH, or CH.sub.2OH; X is H, CH.sub.3, CH.sub.2OH, or CH.sub.2C(O)OH; and
n is 0 or 1.