Conjugation reactions
An initiator for the terminal group of the polymer product of an atom or group radical transfer polymerisation has an activated carboxyl or an amine group which is reacted with an amine or carboxyl (respectively) group containing biologically active compound. The initiator is preferably 4-(3-(2-bromo, 2-methyl-propionate)phenyl)-propionic acid N-hydroxysuccinimide ester or 2-bromo, 2-methyl-propionic acid N-hydroxysuccinimide ester. The monomers preferably comprise a zwitterionic monomer such as 2-methacryloxyethyl-2′-trimethyl ammoniumethyl phosphate inner salt.
1. A process for forming a biologically active conjugate compound, comprising a conjugation step in which a biologically active starting material of the general formula I
is reacted in an amide bond forming step with a reagent of the general formula II
to form an amide-linked conjugate, the process increasing the stability of the biologically active starting material,
in which R is a biologically active moiety;
L 1 is a bond or a divalent organic linker; and
X 1 is —NHR 6 or —COR 7 , in which R 6 is selected from the group consisting of hydrogen, C 1-6 alkyl, aryl and amine activating group and R 7 is hydroxyl or a carboxyl activating group;
X 2 is selected from the group consisting of a polymer formed from ethylenically unsaturated monomers and joined through a terminal group;
R 1 and R 2 are each independently selected from the group consisting of H, halogen, C 1 -C 20 alkyl, C 3 -C 8 cycloalkyl, C(═O)R 15 , C(═O)NR 16 R 17 , COCl, OH, CN, C 2 -C 20 alkenyl, oxiranyl, glycidyl, aryl, heterocyclyl, aralkyl and aralkenyl, in any of which the alkyl, alkenyl or aryl, heterocyclyl or cycloalkyl groups there may be from 1 to 3 substituents selected from the group consisting of hydrogen, hydroxy C 1 -C 4 alkoxy, acyloxy, aryl, heterocyclyl, C(═O)R 15 , C(═O)NR 16 R 17 , oxyranyl and glycidyl; R 15 is selected from the group consisting of alkyl of from 1 to 20 carbon atoms, alkoxy of from 1 to 20 carbon atoms, oligo(alkoxy) in which each alkoxy group has 1 to 3 carbon atoms, aryloxy and heterocyclyloxy, any of which groups may have substituents selected from the group consisting of optionally substituted alkoxy, oligoalkoxy, amino and hydroxyl groups;
R 16 and R 17 are independently selected from the group consisting of H and alkyl of from 1 to 20 carbon atoms which alkyl groups, may have substituents selected from the group consisting of alkoxy, acyl, acyloxy, alkoxycarbonyl, alkenoxycarbonyl, aryl and hydroxy, or R 16 and R 17 may be joined together to form an alkanediyl group of from 2 to 5 carbon atoms, thus forming a 3- to 6-membered ring;
R 3 and R 4 are independently selected from the group consisting of hydrogen, and C 1-6 alkyl, or R 3 and R 4 together are ═O or ═NR 8 where R 8 is hydrogen or C 1-4 alkyl;
R 5 is selected from the group consisting of a bond, —O—, —S— and divalent organic groups;
L 2 is a bond or a divalent linker and,
where X 1 is NHR 6 , X 3 is COR 7 and
where X 1 is COR 7 , X 3 is NHR 6 and
r is an integer of at least 1, and
wherein X 2 is a polymer chain consisting essentially of a homopolymer formed from 2-methacryl oyloxyethyl-2′-trimethylammoniumethyl phosphate inner salt, and the compound of formula I is a protein, and
wherein the compound of formula II is made in a preliminary polymerisation step in which ethylenically unsaturated monomers are polymerised in the presence of an initiator of the general formula XI
in which X 3 , L 2 and R 1 to R 5 are as defined above and X 4 is selected from the group consisting of Cl, Br, I, OR 51 , SR 52 , SeR 52 , OP(═O)R 52 , OP(═O)(OR 52 ) 2 , O—N(R 52 ) 2 and S—C(═S)N(R 52 ) 2 , where R 51 is alkyl of from 1 to 20 carbon atoms in which each of the hydrogen atoms may be independently replaced by halide, R 52 is aryl or a straight or branched C 1 -C 20 alkyl group, and where an N(R 52 ) 2 group is present, the two R 52 groups may be joined to form a 5- or 6-membered heterocyclic ring.
2. A process according to claim 1 in which the ethylenically unsaturated monomers are water-soluble.
3. A process according to claim 2 in which the polymerisation step is carried out in the presence of water.
4. A process according to claim 1 which is carried out in the presence of a catalyst which comprises a transition metal salt and a ligand.
5. A process according to claim 4 in which the ligand is bipyridine, or
where R 50 is a suitable alkyl group triphenylphosphine or 1,1,4,7,10,10-hexamethyl-triethylene tetramine.
6. A process according to claim 4 in which the transition metal salt is copper (1) chloride, copper (1) bromide or ruthenium chloride.