Cytotoxic agents comprising new C-2 modified taxanes

A taxane compound having the following formula (I):

• wherein Z=H or a radical of formula II;
• R1 is a linker or an optionally substituted aryl or heterocyclic radical, alkyl having from 1 to 10 carbon atoms, alkenyl or alkynyl having from 2 to 10 carbon atoms, cycloalkyl or cycloalkenyl having from 3 to 10 carbon atoms, —OR2 or a carbamate formed from any of said alkyl having from 1 to 10 carbon atoms, alkenyl or alkynyl having from 2 to 10 carbon atoms, cycloalkyl or cycloalkenyl having from 3 to 10 carbon atoms, or optionally substituted aryl or heterocyclyl radical;
• R2 is alkyl having from 1 to 10 carbon atoms, alkynyl or alkenyl having from 2 to 10 carbon atoms, cycloalkyl or cycloalkenyl having from 3 to 10 carbon atoms, optionally substituted aryl or heterocyclic radical;
• R3 is a linker or an optionally substituted aryl or heterocyclic radical, alkyl having from 1 to 10 carbon atoms, alkenyl or alkynyl having from 2 to 10 carbon atoms, cycloalkyl or cycloalkenyl having from 3 to 10 carbon atoms;
• R4 is an H or a linker, or an optionally substituted, linear, or branched alkyl radical having from 1 to 10 carbon atoms, alkenyl having from 2 to 10 carbon atoms, alkynyl having from 3 to 10 carbon atoms, cycloalkyl or cycloalkenyl having from 3 to 10 carbon atoms, alkanoyl, alkenoyl, alkynoyl, alkoxyacetyl, alkenyloxyacetyl, alkynyloxyacetyl, alkylthioacetyl, alkenylthioacetyl, alkynylthioacetyl, alkyloxy-carbonyl, alkenyloxycarbonyl, alkynyloxycarbonyl, optionally substituted aryl or heterocyclyl, aroyl or heterocyclylcarbonyl, aryloxycarbonyl or heterocyclyloxy-carbonyl or OR4 forms a carbamate of the formula —OCOX, wherein X is unsubstituted or substituted piperidino, morpholino, piperazino, N-methylpiperazino, or a carbamate of the formula —OCONR8R9, wherein R8 and R9 are the same or different and are H, linear, branched, or cyclic alkyl having from 1 to 10 atoms, alkenyl having from 2 to 10 carbon atoms, alkynyl having from 3 to 10 carbon atoms, cycloalkyl or cycloalkenyl having from 3 to 10 carbon atoms, optionally substituted aryl, or optionally substituted heterocyclyl;
• R5 is H or hydroxyl or a linker, or an optionally substituted, linear, or branched alkyloxy radical having from 1 to 10 carbon atoms, alkenyloxy having from 2 to 10 carbon atoms, alkynyloxy having from 3 to 10 carbon atoms, cycloalkyloxy or cycloalkenyloxy having from 3 to 10 carbon atoms, alkanoyloxy, alkenoyloxy, alkynoyloxy, alkoxyacetoxy, alkenyloxyacetoxy, alkynyloxyacetoxy, alkylthioacetoxy, alkenylthioacetoxy, alkynylthioacetoxy, alkyloxycarbonyloxy, alkenyloxycarbonyloxy, alkynyloxycarbonyloxy, optionally substituted aryloxy or heterocyclyloxy, aroyloxy or heterocyclylcarbonyloxy, aryloxycarbonyloxy or heterocyclyloxycarbonyloxy or OR5 forms a carbamate of the formula —OCOX, wherein X is unsubstituted or substituted piperidino, morpholino, piperazino, N-methylpiperazino, or a carbamate of the formula —OCONR10R11, wherein R10 and R11 are the same or different and are H, linear, branched, or cyclic alkyl having from 1 to 10 atoms, alkenyl having from 2 to 10 carbon atoms, alkynyl having from 3 to 10 carbon atoms, cycloalkyl or cycloalkenyl having from 3 to 10 carbon atoms, optionally substituted aryl, or optionally substituted heterocyclyl;
• R6 is H or hydroxyl or a linker, or an optionally substituted, linear, or branched alkyloxy radical having from 1 to 10 carbon atoms, alkenyloxy having from 2 to 10 carbon atoms, alkynyloxy having from 3 to 10 carbon atoms, cycloalkyloxy or cycloalkenyloxy having from 3 to 10 carbon atoms, alkanoyloxy, alkenoyloxy, alkynoyloxy, alkoxyacetoxy, alkenyloxyacetoxy, alkynyloxyacetoxy, alkylthioacetoxy, alkenylthioacetoxy, alkynylthioacetoxy, alkyloxycarbonyloxy, alkenyloxycarbonyloxy, alkynyloxycarbonyloxy, optionally substituted aryloxy or heterocyclyloxy, aroyloxy or heterocyclylcarbonyloxy, aryloxycarbonyloxy or heterocyclyloxycarbonyloxy or OR6 forms a carbamate of the formula —OCOX, wherein X is unsubstituted or substituted piperidino, morpholino, piperazino, N-methylpiperazino, or a carbamate of the formula —OCONR12R13, wherein R12 and R13 are the same or different and are H, linear, branched, or cyclic alkyl having from 1 to 10 atoms, alkenyl having from 2 to 10 carbon atoms, alkynyl having from 3 to 10 carbon atoms, cycloalkyl or cycloalkenyl having from 3 to 10 carbon atoms, optionally substituted aryl, or optionally substituted heterocyclyl;
• and
• R7 is an optionally substituted heterocyclic radical;
• provided that one, and only one, of R1, R3, R4, R5, or R6 is a linker.

A cytotoxic agent comprising one or more taxanes covalently bonded to a cell binding agent through a linking group, wherein at least one of said taxanes is a compound represented by formula (III):

• wherein:
• R5 is a linker;
• R1 is an optionally substituted aryl or heterocyclic radical, alkyl having from 1 to 10 carbon atoms, alkynyl or alkenyl having from 2 to 10 carbon atoms, cycloalkyl or cycloalkenyl having from 3 to 10 carbon atoms, —OR2 or a carbamate formed from any of said alkyl having from 1 to 10 carbon atoms, alkynyl or alkenyl having from 2 to 10 carbon atoms, cycloalkyl or cycloalkenyl having from 3 to 10 carbon atoms, or optionally substituted aryl or heterocyclyl radical;
• R2 is alkyl having from 1 to 10 carbon atoms, alkynyl or alkenyl having from 2 to 10 carbon atoms, cycloalkyl or cycloalkenyl having from 3 to 10 carbon atoms, optionally substituted aryl or heterocyclic radical;
• R3 is optionally substituted aryl or hetero cyclic radical, alkyl having from 1 to 10 carbon atoms, alkenyl or alkynyl having from 2 to 10 carbon atoms, cycloalkyl or cycloalkenyl having from 3 to 10 carbon atoms;
• R4 is an H or an optionally substituted, linear, or branched alkyl radical having from 1 to 10 carbon atoms, alkenyl having from 2 to 10 carbon atoms, alkynyl having from 3 to 10 carbon atoms, cycloalkyl or cycloalkenyl having from 3 to 10 carbon atoms, alkanoyl, alkenoyl, alkynoyl, alkoxyacetyl, alkenyloxyacetyl, alkynyloxyacetyl, alkylthioacetyl, alkenylthioacetyl, alkynylthioacetyl, alkyloxycarbonyl, alkenyloxy-carbonyl, alkynyloxycarbonyl, optionally substituted aryl or heterocyclyl, aroyl or heterocyclylcarbonyl, aryloxycarbonyl or heterocyclyloxycarbonyl or OR4 forms a carbamate of the formula —OCOX, wherein X is a nitrogen-containing heterocycle, or a carbamate of the formula —OCONR8R9, wherein R8 and R9 are the same or different and are H, linear, branched, or cyclic alkyl having from 1 to 10 atoms, alkenyl having from 2 to 10 carbon atoms, alkynyl having from 3 to 10 carbon atoms, cycloalkyl or cycloalkenyl having from 3 to 10 carbon atoms, optionally substituted aryl, or optionally substituted heterocyclyl;
• R6 is H or hydroxyl or an optionally substituted, linear, or branched alkyloxy radical having from 1 to 10 carbon atoms, alkenyloxy having from 2 to 10 carbon atoms, alkynyloxy having from 3 to 10 carbon atoms, cycloalkyloxy or cycloalkenyloxy having from 3 to 10 carbon atoms, alkanoyloxy, alkenoyloxy, alkynoyloxy, alkoxyacetoxy, alkenyloxyacetoxy, alkynyloxyacetoxy, alkylthioacetoxy, alkenylthioacetoxy, alkynylthioacetoxy, alkyloxycarbonyloxy, alkenyloxycarbonyloxy, alkynyloxycarbonyloxy, optionally substituted aryloxy or heterocyclyloxy, aroyloxy or heterocyclylcarbonyloxy, aryloxycarbonyloxy or heterocyclyloxycarbonyloxy or OR6 forms a carbamate of the formula —OCOX, wherein X is a nitrogen-containing heterocycle, or a carbamate of the formula —OCONR12R13, wherein R12 and R13 are the same or different and are H, linear, branched, or cyclic alkyl having from 1 to 10 atoms, alkenyl having from 2 to 10 carbon atoms, alkynyl having from 3 to 10 carbon atoms, cycloalkyl or cycloalkenyl having from 3 to 10 carbon atoms, optionally substituted aryl, or optionally substituted heterocyclyl;
• and
• R7 is an optionally substituted heterocyclic radical.

A cytotoxic agent comprising one or more taxanes covalently bonded to a cell binding agent through a linker, wherein at least one of said taxanes is a compound represented by formula (III):

• wherein:
• R1 is the linker;
• R3 is optionally substituted aryl or heterocyclic radical, alkyl having from 1 to 10 carbon atoms, alkenyl or alkynyl having from 2 to 10 carbon atoms, cycloalkyl or cycloalkenyl having from 3 to 10 carbon atoms;
• R4 is an H or an optionally substituted, linear, or branched alkyl radical having from 1 to 10 carbon atoms, alkenyl having from 2 to 10 carbon atoms, alkynyl having from 3 to 10 carbon atoms, cycloalkyl or cycloalkenyl having from 3 to 10 carbon atoms, alkanoyl, alkenoyl, alkynoyl, alkoxyacetyl, alkenyloxyacetyl, alkynyloxyacetyl, alkylthioacetyl, alkenylthioacetyl, alkynylthioacetyl, alkyloxycarbonyl, alkenyloxy-carbonyl, alkynyloxycarbonyl, optionally substituted aryl or heterocyclyl, aroyl or heterocyclylcarbonyl, aryloxycarbonyl or heterocyclyloxycarbonyl or OR4 forms a carbamate of the formula —OCOX, wherein X is a nitrogen-containing heterocycle, or a carbamate of the formula —OCONR8R9, wherein R8 and R9 are the same or different and are H, linear, branched, or cyclic alkyl having from 1 to 10 atoms, alkenyl having from 2 to 10 carbon atoms, alkynyl having from 3 to 10 carbon atoms, cycloalkyl or cycloalkenyl having from 3 to 10 carbon atoms, optionally substituted aryl, or optionally substituted heterocyclyl;
• R5 is H or hydroxyl or an optionally substituted, linear, or branched alkyloxy radical having from 1 to 10 carbon atoms, alkenyloxy having from 2 to 10 carbon atoms, alkynyloxy having from 3 to 10 carbon atoms, cycloalkyloxy or cycloalkenyloxy having from 3 to 10 carbon atoms, alkanoyloxy, alkenoyloxy, alkynoyloxy, alkoxyacetoxy, alkenyloxyacetoxy, alkynyloxyacetoxy, alkylthioacetoxy, alkenylthioacetoxy, alkynylthioacetoxy, alkyloxycarbonyloxy, alkenyloxycarbonyloxy, alkynyloxycarbonyloxy, optionally substituted aryloxy or heterocyclyloxy, aroyloxy or heterocyclylcarbonyloxy, aryloxycarbonyloxy or heterocyclyloxycarbonyloxy or OR5 forms a carbamate of the formula —OCOX, wherein X is a nitrogen-containing heterocycle, or a carbamate of the formula —OCONR10R11, wherein R10 and R11 are the same or different and are H, linear, branched, or cyclic alkyl having from 1 to 10 atoms, alkenyl having from 2 to 10 carbon atoms, alkynyl having from 3 to 10 carbon atoms, cycloalkyl or cycloalkenyl having from 3 to 10 carbon atoms, optionally substituted aryl, or optionally substituted heterocyclyl;
• R6 is H or hydroxyl or an optionally substituted, linear, or branched alkyloxy radical having from 1 to 10 carbon atoms, alkenyloxy having from 2 to 10 carbon atoms, alkynyloxy having from 3 to 10 carbon atoms, cycloalkyloxy or cycloalkenyloxy having from 3 to 10 carbon atoms, alkanoyloxy, alkenoyloxy, alkynoyloxy, alkoxyacetoxy, alkenyloxyacetoxy, alkynyloxyacetoxy, alkylthioacetoxy, alkenylthioacetoxy, alkynylthioacetoxy, alkyloxycarbonyloxy, alkenyloxycarbonyloxy, alkynyloxycarbonyloxy, optionally substituted aryloxy or heterocyclyloxy, aroyloxy or heterocyclylcarbonyloxy, aryloxycarbonyloxy or heterocyclyloxycarbonyloxy or OR6 forms a carbamate of the formula —OCOX, wherein X is a nitrogen-containing heterocycle, or a carbamate of the formula —OCONR12R13, wherein R12 and R12 are the same or different and are H, linear, branched, or cyclic alkyl having from 1 to 10 atoms, alkenyl having from 2 to 10 carbon atoms, alkynyl having from 3 to 10 carbon atoms, cycloalkyl or cycloalkenyl having from 3 to 10 carbon atoms, optionally substituted aryl, or optionally substituted heterocyclyl;
• and
• R7 is an optionally substituted heterocyclic radical.

A cytotoxic agent comprising one or more taxanes covalently bonded to a cell binding agent through a linker, wherein at least one of said taxanes is a compound represented by formula (III):

• wherein:
• R3 is the linker;
• R1 is an optionally substituted aryl or heterocyclic radical, alkyl having from 1 to 10 carbon atoms, alkynyl or alkenyl having from 2 to 10 carbon atoms, cycloalkyl or cycloalkenyl having from 3 to 10 carbon atoms, —OR2 or a carbamate formed from any of said alkyl having from 1 to 10 carbon atoms, alkynyl or alkenyl having from 2 to 10 carbon atoms, cycloalkyl or cycloalkenyl having from 3 to 10 carbon atoms, or optionally substituted aryl or heterocyclyl radical;
• R2 is alkyl having from 1 to 10 carbon atoms, alkynyl or alkenyl having from 2 to 10 carbon atoms, cycloalkyl or cycloalkenyl having from 3 to 10 carbon atoms, optionally substituted aryl or heterocyclic radical;
• R4 is an H or an optionally substituted, linear, or branched alkyl radical having from 1 to 10 carbon atoms, alkenyl having from 2 to 10 carbon atoms, alkynyl having from 3 to 10 carbon atoms, cycloalkyl or cycloalkenyl having from 3 to 10 carbon atoms, alkanoyl, alkenoyl, alkynoyl, alkoxyacetyl, alkenyloxyacetyl, alkynyloxyacetyl, alkylthioacetyl, alkenylthioacetyl, alkynylthioacetyl, alkyloxycarbonyl, alkenyloxy-carbonyl, alkynyloxycarbonyl, optionally substituted aryl or heterocyclyl, aroyi or heterocyclylcarbonyl, aryloxycarbonyl or heterocyclyloxycarbonyl or OR4 forms a carbamate of the formula —OCOX, wherein X is a nitrogen-containing heterocycle, or a carbamate of the formula —OCONR8R9, wherein R8 and R9 are the same or different and are H, linear, branched, or cyclic alkyl having from 1 to 10 atoms, alkenyl having from 2 to 10 carbon atoms, alkynyl having from 3 to 10 carbon atoms, cycloalkyl or cycloalkenyl having from 3 to 10 carbon atoms, optionally substituted aryl, or optionally substituted heterocyclyl;
• R5 is H or hydroxyl or an optionally substituted, linear, or branched alkyloxy radical having from 1 to 10 carbon atoms, alkenyloxy having from 2 to 10 carbon atoms, alkynyloxy having from 3 to 10 carbon atoms, cycloalkyloxy or cycloalkenyloxy having from 3 to 10 carbon atoms, alkanoyloxy, alkenoyloxy, alkynoyloxy, alkoxyacetoxy, alkenyloxyacetoxy, alkynyloxyacetoxy, alkylthioacetoxy, alkenylthioacetoxy, alkynylthioacetoxy, alkyloxycarbonyloxy, alkenyloxycarbonyloxy, alkynyloxycarbonyloxy, optionally substituted aryloxy or heterocyclyloxy, aroyloxy or heterocyclylcarbonyloxy, aryloxycarbonyloxy or heterocyclyloxycarbonyloxy or OR5 forms a carbamate of the formula —OCOX, wherein X is a nitrogen-containing heterocycle, or a carbamate of the formula —OCONR10R11, wherein R10 and R11 are the same or different and are H, linear, branched, or cyclic alkyl having from 1 to 10 atoms, alkenyl having from 2 to 10 carbon atoms, alkynyl having from 3 to 10 carbon atoms, cycloalkyl or cycloalkenyl having from 3 to 10 carbon atoms, optionally substituted aryl, or optionally substituted heterocyclyl;
• R6 is H or hydroxyl or an optionally substituted, linear, or branched alkyloxy radical having from 1 to 10 carbon atoms, alkenyloxy having from 2 to 10 carbon atoms, alkynyloxy having from 3 to 10 carbon atoms, cycloalkyloxy or cycloalkenyloxy having from 3 to 10 carbon atoms, alkanoyloxy, alkenoyloxy, alkynoyloxy, alkoxyacetoxy, alkenyloxyacetoxy, alkynyloxyacetoxy, alkylthioacetoxy, alkenylthioacetoxy, alkynylthioacetoxy, alkyloxycarbonyloxy, alkenyloxycarbonyloxy, alkynyloxycarbonyloxy, optionally substituted aryloxy or heterocyclyloxy, aroyloxy or heterocyclylcarbonyloxy, aryloxycarbonyloxy or heterocyclyloxycarbonyloxy or OR6 forms a carbamate of the formula —OCOX, wherein X is a nitrogen-containing heterocycle, or a carbamate of the formula —OCONR12R13, wherein R12 and R13 are the same or different and are H, linear, branched, or cyclic alkyl having from 1 to 10 atoms, alkenyl having from 2 to 10 carbon atoms, alkynyl having from 3 to 10 carbon atoms, cycloalkyl or cycloalkenyl having from 3 to 10 carbon atoms, optionally substituted aryl, or optionally substituted heterocyclyl;
• and
• R7 is an optionally substituted heterocyclic radical.

A cytotoxic agent comprising one or more taxanes covalently bonded to a cell binding agent through a linker, wherein at least one of said taxanes is a compound represented by formula (III):

• wherein:
• R4 is the linker;
• R1 is an optionally substituted aryl or heterocyclic radical, alkyl having from 1 to 10 carbon atoms, alkynyl or alkenyl having from 2 to 10 carbon atoms, cycloalkyl or cycloalkenyl having from 3 to 10 carbon atoms, —OR2 or a carbamate formed from any of said alkyl having from 1 to 10 carbon atoms, alkynyl or alkenyl having from 2 to 10 carbon atoms, cycloalkyl or cycloalkenyl having from 3 to 10 carbon atoms, or optionally substituted aryl or heterocyclyl radical;
• R2 is alkyl having from 1 to 10 carbon atoms, alkynyl or alkenyl having from 2 to 10 carbon atoms, cycloalkyl or cycloalkenyl having from 3 to 10 carbon atoms, optionally substituted aryl or heterocyclic radical;
• R3 is optionally substituted aryl or heterocyclic radical, alkyl having from 1 to 10 carbon atoms, alkenyl or alkynyl having from 2 to 10 carbon atoms, cycloalkyl or cycloalkenyl having from 3 to 10 carbon atoms;
• R5 is H or hydroxyl or an optionally substituted, linear, or branched alkyloxy radical having from 1 to 10 carbon atoms, alkenyloxy having from 2 to 10 carbon atoms, alkynyloxy having from 3 to 10 carbon atoms, cycloalkyloxy or cycloalkenyloxy having from 3 to 10 carbon atoms, alkanoyloxy, alkenoyloxy, alkynoyloxy, alkoxyacetoxy, alkenyloxyacetoxy, alkynyloxyacetoxy, alkylthioacetoxy, alkenylthioacetoxy, alkynylthioacetoxy, alkyloxycarbonyloxy, alkenyloxycarbonyloxy, alkynyloxycarbonyloxy, optionally substituted aryloxy or heterocyclyloxy, aroyloxy or heterocyclylcarbonyloxy, aryloxycarbonyloxy or heterocyclyloxycarbonyloxy or OR5 forms a carbamate of the formula —OCOX, wherein X is a nitrogen-containing heterocycle, or a carbamate of the formula —OCONR10R11, wherein R10 and R11 are the same or different and are H, linear, branched, or cyclic alkyl having from 1 to 10 atoms, alkenyl having from 2 to 10 carbon atoms, alkynyl having from 3 to 10 carbon atoms, cycloalkyl or cycloalkenyl having from 3 to 10 carbon atoms, optionally substituted aryl, or optionally substituted heterocyclyl;
• R6 is H or hydroxyl or an optionally substituted, linear, or branched alkyloxy radical having from 1 to 10 carbon atoms, alkenyloxy having from 2 to 10 carbon atoms, alkynyloxy having from 3 to 10 carbon atoms, cycloalkyloxy or cycloalkenyloxy having from 3 to 10 carbon atoms, alkanoyloxy, alkenoyloxy, alkynoyloxy, alkoxyacetoxy, alkenyloxyacetoxy, alkynyloxyacetoxy, alkylthioacetoxy, alkenylthioacetoxy, alkynylthioacetoxy, alkyloxycarbonyloxy, alkenyloxycarbonyloxy, alkynyloxycarbonyloxy, optionally substituted aryloxy or heterocyclyloxy, aroyloxy or heterocyclylcarbonyloxy, aryloxycarbonyloxy or heterocyclyloxycarbonyloxy or OR6 forms a carbamate of the formula —OCOX, wherein X is a nitrogen-containing heterocycle, or a carbamate of the formula —OCONR12R3, wherein R12 and R13 are the same or different and are H, linear, branched, or cyclic alkyl having from 1 to 10 atoms, alkenyl having from 2 to 10 carbon atoms, alkynyl having from 3 to 10 carbon atoms, cycloalkyl or cycloalkenyl having from 3 to 10 carbon atoms, optionally substituted aryl, or optionally substituted heterocyclyl;
• and
• R7 is an optionally substituted heterocyclic radical.

A cytotoxic agent comprising one or more taxanes covalently bonded to a cell binding agent through a linker, wherein at least one of said taxanes is a compound represented by formula (III):

• wherein:
• R6 is the linker;
• R1 is an optionally substituted aryl or heterocyclic radical, alkyl having from 1 to 10 carbon atoms, alkynyl or alkenyl having from 2 to 10 carbon atoms, cycloalkyl or cycloalkenyl having from 3 to 10 carbon atoms, —OR2 or a carbamate formed from any of said alkyl having from 1 to 10 carbon atoms, alkynyl or alkenyl having from 2 to 10 carbon atoms, cycloalkyl or cycloalkenyl having from 3 to 10 carbon atoms, or optionally substituted aryl or heterocyclyl radical;
• R2 is alkyl having from 1 to 10 carbon atoms, alkynyl or alkenyl having from 2 to 10 carbon atoms, cycloalkyl or cycloalkenyl having from 3 to 10 carbon atoms, optionally substituted aryl or heterocyclic radical;
• R3 is optionally substituted aryl or heterocyclic radical, alkyl having from 1 to 10 carbon atoms, alkenyl or alkynyl having from 2 to 10 carbon atoms, cycloalkyl or cycloalkenyl having from 3 to 10 carbon atoms;
• R4 is an H or an optionally substituted, linear, or branched alkyl radical having from 1 to 10 carbon atoms, alkenyl having from 2 to 10 carbon atoms, alkynyl having from 3 to 10 carbon atoms, cycloalkyl or cycloalkenyl having from 3 to 10 carbon atoms, alkanoyl, alkenoyl, alkynoyl, alkoxyacetyl, alkenyloxyacetyl, alkynyloxyacetyl, alkylthioacetyl, alkenylthioacetyl, alkynylthioacetyl, alkyloxycarbonyl, alkenyloxy-carbonyl, alkynyloxycarbonyl, optionally substituted aryl or heterocyclyl, aroyl or heterocyclylcarbonyl, aryloxycarbonyl or heterocyclyloxycarbonyl or OR4 forms a carbamate of the formula —OCOX, wherein X is a nitrogen-containing heterocycle, or a carbamate of the formula —OCONR8R9, wherein R8 and R9 are the same or different and are H, linear, branched, or cyclic alkyl having from 1 to 10 atoms, alkenyl having from 2 to 10 carbon atoms, alkynyl having from 3 to 10 carbon atoms, cycloalkyl or cycloalkenyl having from 3 to 10 carbon atoms, optionally substituted aryl, or optionally substituted heterocyclyl;
• R5 is H or hydroxyl or an optionally substituted, linear, or branched alkyloxy radical having from 1 to 10 carbon atoms, alkenyloxy having from 2 to 10 carbon atoms, alkynyloxy having from 3 to 10 carbon atoms, cycloalkyloxy or cycloalkenyloxy having from 3 to 10 carbon atoms, alkanoyloxy, alkenoyloxy, alkynoyloxy, alkoxyacetoxy, alkenyloxyacetoxy, alkynyloxyacetoxy, alkylthioacetoxy, alkenylthioacetoxy, alkynylthioacetoxy, alkyloxycarbonyloxy, alkenyloxycarbonyloxy, alkynyloxycarbonyloxy, optionally substituted aryloxy or heterocyclyloxy, aroyloxy or heterocyclylcarbonyloxy, aryloxycarbonyloxy or heterocyclyloxycarbonyloxy or OR5 R6 is H or hydroxyl or a linker, or an optionally substituted, linear, or branched alkyloxy radical having from 1 to 10 carbon atoms, alkenyloxy having from 2 to 10 carbon atoms, alkynyloxy having from 3 to 10 carbon atoms, cycloalkyloxy or cycloalkenyloxy having from 3 to 10 carbon atoms, alkanoyloxy, alkenoyloxy, alkynoyloxy, alkoxyacetoxy, alkenyloxyacetoxy, alkynyloxyacetoxy, alkylthioacetoxy, alkenylthioacetoxy, alkynylthioacetoxy, alkyloxycarbonyloxy, alkenyloxycarbonyloxy, alkynyloxycarbonyloxy, optionally substituted aryloxy or heterocyclyloxy, aroyloxy or heterocyclylcarbonyloxy, aryloxycarbonyloxy or heterocyclyloxycarbonyloxy or OR6 forms a carbamate of the formula —OCOX, wherein X is a nitrogen-containing heterocycle, or a carbamate of the formula —OCONR12R13, wherein R12 and R13 are the same or different and are H, linear, branched, or cyclic alkyl having from 1 to 10 atoms, alkenyl having from 2 to 10 carbon atoms, alkynyl having from 3 to 10 carbon atoms, cycloalkyl or cycloalkenyl having from 3 to 10 carbon atoms, optionally substituted aryl, or optionally substituted heterocyclyl;
• and
• R7 is an optionally substituted heterocyclic radical.