Patent ID: 8067616

Claim:
A compound of formula (X): wherein: R 1 is hydrogen or substituted or unsubstituted C 1-6 alkyl; R 3 is selected from the group consisting of substituted or unsubstituted variants of the following: C 1-6 alkyl, C 3-6 cycloalkyl, C 2-6 alkenyl, C 3-6 cycloalkenyl, aryl, and arylalkyl; R 4 can be selected from the group consisting of substituted or unsubstituted variants of the following: C 1 -C 12 alkyl, C 2 -C 12 alkenyl, C 2 -C 12 alkynyl, C 3 -C 12 cycloalkyl, C 3 -C 12 cycloalkenyl, C 3 -C 12 cycloalkynyl, C 3 -C 12 heterocyclyl, aryl, heteroaryl, arylalkyl, heteroarylalkyl, (cycloalkyl)alkyl, (heterocyclyl)alkyl, acyl, acylalkyl, alkyloxycarbonyloxy, carbonylacyl, aminocarbonyl, azido, azidoalkyl, aminoalkyl, salt of an aminoalkyl, carboxyalkyl, salt of carboxyalkyl, alkylaminoalkyl, salt of an alkylaminoalkyl, dialkylaminoalkyl, salt of a dialkylaminoalkyl, phenyl, alkylthioalkyl, arylthioalkyl, carboxy, cyano, alkanesulfonylalkyl, alkanesulfinylalkyl, alkoxysulfinylalkyl, thiocyanoalkyl, boronic acidalkyl, boronic esteralkyl, guanidinoalkyl, salt of a guanidinoalkyl, sulfoalkyl, salt of a sulfoalkyl, alkoxysulfonylalkyl, sulfooxyalkyl, salt of a sulfooxyalkyl, alkoxysulfonyloxyalkyl, phosphonooxyalkyl, salt of a phosphonooxyalkyl, (alkylphosphooxy)alkyl, phosphorylalkyl, salt of a phosphorylalkyl, (alkylphosphoryl)alkyl, pyridinylalkyl, salt of a pyridinylalkyl, salt of a heteroarylalkyl and halogenated alkyl including polyhalogenated alkyl; and PG 1 is a protecting group moiety.