| 主权项 |
1. A compound represented by Formula I or a pharmaceutically acceptable salt, ester, stereoisomer, tautomer, solvate, or combination thereof: wherein: X is absent, —C(O)NH— or —NH—; R1 is selected from the group consisting of: 1) Hydrogen; 2) Substituted or unsubstituted —C1-C8 alkyl; 3) Substituted or unsubstituted —C2-C8 alkenyl; 4) Substituted or unsubstituted —C2-C8 alkynyl; 5) Substituted or unsubstituted arylalkyl; and 6) Substituted or unsubstituted aryl; m is 0, 1, 2 or 3; R2 is hydrogen, hydroxyl, —OSO3H, —OSO3−, —OAc, —OPO3H2 or —OPO32−; preferably R2 is hydrogen or hydroxyl; R3 is hydrogen, halogen, CN, N3, hydroxyl, —OSO3H, —OSO3−, —OAc, —OPO3H2, —OPO32−, —SR1 or —NHR1, wherein R1 is as defined previously; Or R2 and R3 are taken together with the carbon atoms to which they are attached to form —CH═CH— or cycloalkyl ring or heterocycloalkyl ring such as, but not limited to cyclopropyl, or epoxide; R4 and R5 are independently selected from hydrogen or hydroxyl protecting group; and R6 is selected from the group consisting of: 1) Hydrogen; 2) Halogen; 3) Substituted or unsubstituted —C1-C8 alkyl; 4) Substituted or unsubstituted —C2-C8 alkenyl; 5) Substituted or unsubstituted —C2-C8 alkynyl; and 6) Substituted or unsubstituted —C3-C8 cycloalkyl. |
