The present application relates to a disaccharide linker, a disaccharide-small molecule drug conjugate and a sugar chain fixed-point antibody-drug conjugate, a preparation method and the use thereof. The structure of the disaccharide linker is as shown in the following formula I. The present invention provides a new-type fixed-point and quantitative antibody-drug conjugate form, and the stability and cytotoxicity of the antibody-drug conjugate are improved.

##STR00001##

The present invention is directed to a process for making Chloro-Substituted Nucleoside Phosphoramidate Compounds of formula (I):

##STR00001##

which are useful for the treatment and prophylaxis of HCV infection. The present invention is also directed to compounds that are useful as synthetic intermediates for making the compounds of formula (I).

The present invention is directed to a process for making Chloro-Substituted Nucleoside Phosphoramidate Compounds of formula (I): ##STR00001##
which are useful for the treatment and prophylaxis of HCV infection. The present invention is also directed to compounds that are useful as synthetic intermediates for making the compounds of formula (I).

The present invention provides a method for producing guanidine crosslinked artificial nucleic acid (abbreviated hereinafter as GuNA), and an intermediate compound for the production thereof. Specifically, the present invention provides a method for producing a compound represented by general formula I: (in the formula, R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6, m and ring A are as defined in the specification) or a salt thereof wherein a reducing agent is reacted with a compound represented by general formula II: (in the formula, R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6, m, and ring A are as defined in the specification).

##STR00001##

The present invention provides a method for producing guanidine crosslinked artificial nucleic acid (abbreviated hereinafter as GuNA), and an intermediate compound for the production thereof. Specifically, the present invention provides a method for producing a compound represented by general formula I: (in the formula, R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6, m and ring A are as defined in the specification) or a salt thereof wherein a reducing agent is reacted with a compound represented by general formula II: (in the formula, R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6, m, and ring A are as defined in the specification).

##STR00001##

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.

The invention provides compounds 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 invention provides compounds 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 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.