Patent ID: 8741891

Claim:
A compound of Formula I: or a pharmaceutically acceptable salt thereof wherein R is selected from the group consisting of hydrogen, a hydrolysable group selected from the group consisting of —C(O)R 2 , —C(O)NR 3 R 4 and —C(O)OR 5 , where R 2 is selected from the group consisting of hydrogen, alkyl, substituted alkyl, alkenyl, substituted alkenyl, alkynyl and substituted alkynyl, R 3 and R 4 are independently selected from the group consisting of hydrogen, alkyl, substituted alkyl, alkenyl, substituted alkenyl, alkynyl, substituted alkynyl, aryl, substituted aryl, heteroaryl, substituted heteroaryl, heterocyclic and substituted heterocyclic, R 5 is selected from the group consisting of alkyl, substituted alkyl, alkenyl, substituted alkenyl, alkynyl, substituted alkynyl, aryl, substituted aryl, heteroaryl, substituted heteroaryl, heterocyclic and substituted heterocyclic, provided that R is not a saccharide or an oligosaccharide; L is selected from the group consisting of a covalent bond and a cleavable linker group; R 1 is selected from the group consisting of hydrogen, substituted alkyl, alkenyl, substituted alkenyl, alkynyl, substituted alkynyl, aryl, substituted aryl, cycloalkyl, substituted cycloalkyl, heteroaryl, substituted heteroaryl, heterocyclic, and substituted heterocyclic, provided that R 1 is not a saccharide or an oligosaccharide; or pharmaceutically acceptable salts thereof, provided that when L is a covalent bond and R 1 is hydrogen, then R is selected from the group consisting of —C(O)NR 3 R 4 and —C(O)OR 5 ; and further provided that when R is hydrogen or —C(O)R 2 and L is a covalent bond, then R 1 is not hydrogen.