Patent ID: 7087600

Claim:
A compound having the structure: or a pharmaceutically acceptable salt thereof; wherein X and Z are members independently selected from O, S and NR 23 wherein R 23 is a member selected from H, substituted or unsubstituted alkyl, substituted or unsubstituted heteroalkyl, and acyl; R 1 is CO 2 CH 3 ; R 2 is H, or substituted or unsubstituted lower alkyl; R 11 is C(O)NR 12 R 13 in which R 12 , and R 13 are members independently selected from H, substituted or unsubstituted alkyl, substituted or unsubstituted heteroalkyl and substituted or unsubstituted aryl, and at least one of R 12 and R 13 comprises a cleaveable group; R 4 and R 5 are members independently selected from H, substituted or unsubstituted alkyl, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, substituted or unsubstituted heterocycloalkyl, halogen, NO 2 , NR 15 R 16 , NC(O)R 15 , OC(O)NR 15 R 16 , OC(O)OR 15 , C(O)R 15 , OR 15 wherein R 15 and R 16 are independently selected from H, substituted or unsubstituted alkyl, substituted or unsubstituted heteroalkyl, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, substituted or unsubstituted heterocycloalkyl and substituted or unsubstituted peptidyl, wherein R 15 and R 16 together with the nitrogen atom to which they are attached are optionally joined to form a substituted or unsubstituted heterocycloalkyl ring system having from 4 to 6 members, optionally containing two or more heteroatoms; and X 1 is a leaving group.